The Meta Referrer Tag: An Advancement for SEO and the Internet

Posted by Cyrus-Shepard

The movement to make the Internet more secure through HTTPS brings several useful advancements for webmasters. In addition to security improvements, HTTPS promises future technological advances and potential SEO benefits for marketers.

HTTPS in search results is rising. Recent MozCast data from Dr. Pete shows nearly 20% of first page Google results are now HTTPS.

Sadly, HTTPS also has its downsides.

Marketers run into their first challenge when they switch regular HTTP sites over to HTTPS. Technically challenging, the switch typically involves routing your site through a series of 301 redirects. Historically, these types of redirects are associated with a loss of link equity (thought to be around 15%) which can lead to a loss in rankings. This can offset any SEO advantage that Google claims switching.

Ross Hudgens perfectly summed it up in this tweet:

Many SEOs have anecdotally shared stories of HTTPS sites performing well in Google search results (and our soon-to-be-published Ranking Factors data seems to support this.) However, the short term effect of a large migration can be hard to take. When Moz recently switched to HTTPS to provide better security to our logged-in users, we saw an 8-9% dip in our organic search traffic.

Problem number two is the subject of this post. It involves the loss of referral data. Typically, when one site sends traffic to another, information is sent that identifies the originating site as the source of traffic. This invaluable data allows people to see where their traffic is coming from, and helps spread the flow of information across the web.

SEOs have long used referrer data for a number of beneficial purposes. Oftentimes, people will link back or check out the site sending traffic when they see the referrer in their analytics data. Spammers know this works, as evidenced by the recent increase in referrer spam:

This process stops when traffic flows from an HTTPS site to a non-secure HTTP site. In this case, no referrer data is sent. Webmasters can’t know where their traffic is coming from.

Here’s how referral data to my personal site looked when Moz switched to HTTPS. I lost all visibility into where my traffic came from.

Its (not provided) all over again!

Enter the meta referrer tag

While we can’t solve the ranking challenges imposed by switching a site to HTTPS, we can solve the loss of referral data, and it’s actually super-simple.

Almost completely unknown to most marketers, the relatively new meta referrer tag (it’s actually been around for a few years) was designed to help out in these situations.

Better yet, the tag allows you to control how your referrer information is passed.

The meta referrer tag works with most browsers to pass referrer information in a manner defined by the user. Traffic remains encrypted and all the benefits of using HTTPS remain in place, but now you can pass referrer data to all websites, even those that use HTTP.

How to use the meta referrer tag

What follows are extremely simplified instructions for using the meta referrer tag. For more in-depth understanding, we highly recommend referring to the W3C working draft of the spec.

The meta referrer tag is placed in the <head> section of your HTML, and references one of five states, which control how browsers send referrer information from your site. The five states are:

  1. None: Never pass referral data
    <meta name="referrer" content="none">
    
  2. None When Downgrade: Sends referrer information to secure HTTPS sites, but not insecure HTTP sites
    <meta name="referrer" content="none-when-downgrade">
    
  3. Origin Only: Sends the scheme, host, and port (basically, the subdomain) stripped of the full URL as a referrer, i.e. https://moz.com/example.html would simply send https://moz.com
    <meta name="referrer" content="origin">
    

  4. Origin When Cross-Origin: Sends the full URL as the referrer when the target has the same scheme, host, and port (i.e. subdomain) regardless if it’s HTTP or HTTPS, while sending origin-only referral information to external sites. (note: There is a typo in the official spec. Future versions should be “origin-when-cross-origin”)
    <meta name="referrer" content="origin-when-crossorigin">
    
  5. Unsafe URL: Always passes the URL string as a referrer. Note if you have any sensitive information contained in your URL, this isn’t the safest option. By default, URL fragments, username, and password are automatically stripped out.
    <meta name="referrer" content="unsafe-url">
    

The meta referrer tag in action

By clicking the link below, you can get a sense of how the meta referrer tag works.

Check Referrer

Boom!

We’ve set the meta referrer tag for Moz to “origin”, which means when we link out to another site, we pass our scheme, host, and port. The end result is you see http://moz.com as the referrer, stripped of the full URL path (/meta-referrer-tag).

My personal site typically receives several visits per day from Moz. Here’s what my analytics data looked like before and after we implemented the meta referrer tag.

For simplicity and security, most sites may want to implement the “origin” state, but there are drawbacks.

One negative side effect was that as soon as we implemented the meta referrer tag, our AdRoll analytics, which we use for retargeting, stopped working. It turns out that AdRoll uses our referrer information for analytics, but the meta referrer tag “origin” state meant that the only URL they ever saw reported was https://moz.com.

Conclusion

We love the meta referrer tag because it keeps information flowing on the Internet. It’s the way the web is supposed to work!

It helps marketers and webmasters see exactly where their traffic is coming from. It encourages engagement, communication, and even linking, which can lead to improvements in SEO.

Useful links:

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Big Data, Big Problems: 4 Major Link Indexes Compared

Posted by russangular

Given this blog’s readership, chances are good you will spend some time this week looking at backlinks in one of the growing number of link data tools. We know backlinks continue to be one of, if not the most important
parts of Google’s ranking algorithm. We tend to take these link data sets at face value, though, in part because they are all we have. But when your rankings are on the line, is there a better way to get at which data set is the best? How should we go
about assessing these different link indexes like
Moz,
Majestic, Ahrefs and SEMrush for quality? Historically, there have been 4 common approaches to this question of index quality…

  • Breadth: We might choose to look at the number of linking root domains any given service reports. We know
    that referring domains correlates strongly with search rankings, so it makes sense to judge a link index by how many unique domains it has
    discovered and indexed.
  • Depth: We also might choose to look at how deep the web has been crawled, looking more at the total number of URLs
    in the index, rather than the diversity of referring domains.
  • Link Overlap: A more sophisticated approach might count the number of links an index has in common with Google Webmaster
    Tools.
  • Freshness: Finally, we might choose to look at the freshness of the index. What percentage of links in the index are
    still live?

There are a number of really good studies (some newer than others) using these techniques that are worth checking out when you get a chance:

  • BuiltVisible analysis of Moz, Majestic, GWT, Ahrefs and Search Metrics
  • SEOBook comparison of Moz, Majestic, Ahrefs, and Ayima
  • MatthewWoodward
    study of Ahrefs, Majestic, Moz, Raven and SEO Spyglass
  • Marketing Signals analysis of Moz, Majestic, Ahrefs, and GWT
  • RankAbove comparison of Moz, Majestic, Ahrefs and Link Research Tools
  • StoneTemple study of Moz and Majestic

While these are all excellent at addressing the methodologies above, there is a particular limitation with all of them. They miss one of the
most important metrics we need to determine the value of a link index: proportional representation to Google’s link graph
. So here at Angular Marketing, we decided to take a closer look.

Proportional representation to Google Search Console data

So, why is it important to determine proportional representation? Many of the most important and valued metrics we use are built on proportional
models. PageRank, MozRank, CitationFlow and Ahrefs Rank are proportional in nature. The score of any one URL in the data set is relative to the
other URLs in the data set. If the data set is biased, the results are biased.

A Visualization

Link graphs are biased by their crawl prioritization. Because there is no full representation of the Internet, every link graph, even Google’s,
is a biased sample of the web. Imagine for a second that the picture below is of the web. Each dot represents a page on the Internet,
and the dots surrounded by green represent a fictitious index by Google of certain sections of the web.

Of course, Google isn’t the only organization that crawls the web. Other organizations like Moz,
Majestic, Ahrefs, and SEMrush
have their own crawl prioritizations which result in different link indexes.

In the example above, you can see different link providers trying to index the web like Google. Link data provider 1 (purple) does a good job
of building a model that is similar to Google. It isn’t very big, but it is proportional. Link data provider 2 (blue) has a much larger index,
and likely has more links in common with Google that link data provider 1, but it is highly disproportional. So, how would we go about measuring
this proportionality? And which data set is the most proportional to Google?

Methodology

The first step is to determine a measurement of relativity for analysis. Google doesn’t give us very much information about their link graph.
All we have is what is in Google Search Console. The best source we can use is referring domain counts. In particular, we want to look at
what we call
referring domain link pairs. A referring domain link pair would be something like ask.com->mlb.com: 9,444 which means
that ask.com links to mlb.com 9,444 times.

Steps

  1. Determine the root linking domain pairs and values to 100+ sites in Google Search Console
  2. Determine the same for Ahrefs, Moz, Majestic Fresh, Majestic Historic, SEMrush
  3. Compare the referring domain link pairs of each data set to Google, assuming a
    Poisson Distribution
  4. Run simulations of each data set’s performance against each other (ie: Moz vs Maj, Ahrefs vs SEMrush, Moz vs SEMrush, et al.)
  5. Analyze the results

Results

When placed head-to-head, there seem to be some clear winners at first glance. In head-to-head, Moz edges out Ahrefs, but across the board, Moz and Ahrefs fare quite evenly. Moz, Ahrefs and SEMrush seem to be far better than Majestic Fresh and Majestic Historic. Is that really the case? And why?

It turns out there is an inversely proportional relationship between index size and proportional relevancy. This might seem counterintuitive,
shouldn’t the bigger indexes be closer to Google? Not Exactly.

What does this mean?

Each organization has to create a crawl prioritization strategy. When you discover millions of links, you have to prioritize which ones you
might crawl next. Google has a crawl prioritization, so does Moz, Majestic, Ahrefs and SEMrush. There are lots of different things you might
choose to prioritize…

  • You might prioritize link discovery. If you want to build a very large index, you could prioritize crawling pages on sites that
    have historically provided new links.
  • You might prioritize content uniqueness. If you want to build a search engine, you might prioritize finding pages that are unlike
    any you have seen before. You could choose to crawl domains that historically provide unique data and little duplicate content.
  • You might prioritize content freshness. If you want to keep your search engine recent, you might prioritize crawling pages that
    change frequently.
  • You might prioritize content value, crawling the most important URLs first based on the number of inbound links to that page.

Chances are, an organization’s crawl priority will blend some of these features, but it’s difficult to design one exactly like Google. Imagine
for a moment that instead of crawling the web, you want to climb a tree. You have to come up with a tree climbing strategy.

  • You decide to climb the longest branch you see at each intersection.
  • One friend of yours decides to climb the first new branch he reaches, regardless of how long it is.
  • Your other friend decides to climb the first new branch she reaches only if she sees another branch coming off of it.

Despite having different climb strategies, everyone chooses the same first branch, and everyone chooses the same second branch. There are only
so many different options early on.

But as the climbers go further and further along, their choices eventually produce differing results. This is exactly the same for web crawlers
like Google, Moz, Majestic, Ahrefs and SEMrush. The bigger the crawl, the more the crawl prioritization will cause disparities. This is not a
deficiency; this is just the nature of the beast. However, we aren’t completely lost. Once we know how index size is related to disparity, we
can make some inferences about how similar a crawl priority may be to Google.

Unfortunately, we have to be careful in our conclusions. We only have a few data points with which to work, so it is very difficult to be
certain regarding this part of the analysis. In particular, it seems strange that Majestic would get better relative to its index size as it grows,
unless Google holds on to old data (which might be an important discovery in and of itself). It is most likely that at this point we can’t make
this level of conclusion.

So what do we do?

Let’s say you have a list of domains or URLs for which you would like to know their relative values. Your process might look something like
this…

  • Check Open Site Explorer to see if all URLs are in their index. If so, you are looking metrics most likely to be proportional to Google’s link graph.
  • If any of the links do not occur in the index, move to Ahrefs and use their Ahrefs ranking if all you need is a single PageRank-like metric.
  • If any of the links are missing from Ahrefs’s index, or you need something related to trust, move on to Majestic Fresh.
  • Finally, use Majestic Historic for (by leaps and bounds) the largest coverage available.

It is important to point out that the likelihood that all the URLs you want to check are in a single index increases as the accuracy of the metric
decreases. Considering the size of Majestic’s data, you can’t ignore them because you are less likely to get null value answers from their data than
the others. If anything rings true, it is that once again it makes sense to get data
from as many sources as possible. You won’t
get the most proportional data without Moz, the broadest data without Majestic, or everything in-between without Ahrefs.

What about SEMrush? They are making progress, but they don’t publish any relative statistics that would be useful in this particular
case. Maybe we can hope to see more from them soon given their already promising index!

Recommendations for the link graphing industry

All we hear about these days is big data; we almost never hear about good data. I know that the teams at Moz,
Majestic, Ahrefs, SEMrush and others are interested in mimicking Google, but I would love to see some organization stand up against the
allure of
more data in favor of better data—data more like Google’s. It could begin with testing various crawl strategies to see if they produce
a result more similar to that of data shared in Google Search Console. Having the most Google-like data is certainly a crown worth winning.

Credits

Thanks to Diana Carter at Angular for assistance with data acquisition and Andrew Cron with statistical analysis. Thanks also to the representatives from Moz, Majestic, Ahrefs, and SEMrush for answering questions about their indices.

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The Colossus Update: Waking The Giant

Posted by Dr-Pete

Yesterday morning, we woke up to a historically massive temperature spike on MozCast, after an unusually quiet weekend. The 10-day weather looked like this:

That’s 101.8°F, one of the hottest verified days on record, second only to a series of unconfirmed spikes in June of 2013. For reference, the first Penguin update clocked in at 93.1°.

Unfortunately, trying to determine how the algorithm changed from looking at individual keywords (even thousands of them) is more art than science, and even the art is more often Ms. Johnson’s Kindergarten class than Picasso. Sometimes, though, we catch a break and spot something.

The First Clue: HTTPS

When you watch enough SERPs, you start to realize that change is normal. So, the trick is to find the queries that changed a lot on the day in question but are historically quiet. Looking at a few of these, I noticed some apparent shake-ups in HTTP vs. HTTPS (secure) URLs. So, the question becomes: are these anecdotes, or do they represent a pattern?

I dove in and looked at how many URLs for our 10,000 page-1 SERPs were HTTPS over the past few days, and I saw this:

On the morning of June 17, HTTPS URLs on page 1 jumped from 16.9% to 18.4% (a 9.9% day-over-day increase), after trending up for a few days. This represents the total real-estate occupied by HTTPS URLs, but how did rankings fare? Here are the average rankings across all HTTPS results:

HTTPS URLs also seem to have gotten a rankings boost – dropping (with “dropping” being a positive thing) from an average of 2.96 to 2.79 in the space of 24 hours.

Seems pretty convincing, right? Here’s the problem: rankings don’t just change because Google changes the algorithm. We are, collectively, changing the web every minute of the day. Often, those changes are just background noise (and there’s a lot of noise), but sometimes a giant awakens.

The Second Clue: Wikipedia

Anecdotally, I noticed that some Wikipedia URLs seemed to be flipping from HTTP to HTTPS. I ran a quick count, and this wasn’t just a fluke. It turns out that Wikipedia started switching their entire site to HTTPS around June 12 (hat tip to Jan Dunlop). This change is expected to take a couple of weeks.

It’s just one site, though, right? Well, historically, this one site is the #1 largest land-holder across the SERP real-estate we track, with over 5% of the total page-1 URLs in our tracking data (5.19% as of June 17). Wikipedia is a giant, and its movements can shake the entire web.

So, how do we tease this apart? If Wikipedia’s URLs had simply flipped from HTTP to HTTPS, we should see a pretty standard pattern of shake-up. Those URLs would look to have changed, but the SERPS around them would be quiet. So, I ran an analysis of what the temperature would’ve been if we ignored the protocol (treating HTTP/HTTPS as the same). While slightly lower, that temperature was still a scorching 96.6°F.

Is it possible that Wikipedia moving to HTTPS also made the site eligible for a rankings boost from previous algorithm updates, thus disrupting page 1 without any code changes on Google’s end? Yes, it is possible – even a relatively small rankings boost for Wikipedia from the original HTTPS algorithm update could have a broad impact.

The Third Clue: Google?

So far, Google has only said that this was not a Panda update. There have been rumors that the HTTPS update would get a boost, as recently as SMX Advanced earlier this month, but no timeline was given for when that might happen.

Is it possible that Wikipedia’s publicly announced switch finally gave Google the confidence to boost the HTTPS signal? Again, yes, it’s possible, but we can only speculate at this point.

My gut feeling is that this was more than just a waking giant, even as powerful of a SERP force as Wikipedia has become. We should know more as their HTTPS roll-out continues and their index settles down. In the meantime, I think we can expect Google to become increasingly serious about HTTPS, even if what we saw yesterday turns out not to have been an algorithm update.

In the meantime, I’m going to melodramatically name this “The Colossus Update” because, well, it sounds cool. If this indeed was an algorithm update, I’m sure Google would prefer something sensible, like “HTTPS Update 2” or “Securageddon” (sorry, Gary).

Update from Google: Gary Illyes said that he’s not aware of an HTTPS update (via Twitter):

No comment on other updates, or the potential impact of a Wikipedia change. I feel strongly that there is an HTTPS connection in the data, but as I said – that doesn’t necessarily mean the algorithm changed.

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Deconstructing the App Store Rankings Formula with a Little Mad Science

Posted by AlexApptentive

After seeing Rand’s “Mad Science Experiments in SEO” presented at last year’s MozCon, I was inspired to put on the lab coat and goggles and do a few experiments of my own—not in SEO, but in SEO’s up-and-coming younger sister, ASO (app store optimization).

Working with Apptentive to guide enterprise apps and small startup apps alike to increase their discoverability in the app stores, I’ve learned a thing or two about app store optimization and what goes into an app’s ranking. It’s been my personal goal for some time now to pull back the curtains on Google and Apple. Yet, the deeper into the rabbit hole I go, the more untested assumptions I leave in my way.

Hence, I thought it was due time to put some longstanding hypotheses through the gauntlet.

As SEOs, we know how much of an impact a single ranking can mean on a SERP. One tiny rank up or down can make all the difference when it comes to your website’s traffic—and revenue.

In the world of apps, ranking is just as important when it comes to standing out in a sea of more than 1.3 million apps. Apptentive’s recent mobile consumer survey shed a little more light this claim, revealing that nearly half of all mobile app users identified browsing the app store charts and search results (the placement on either of which depends on rankings) as a preferred method for finding new apps in the app stores. Simply put, better rankings mean more downloads and easier discovery.

Like Google and Bing, the two leading app stores (the Apple App Store and Google Play) have a complex and highly guarded algorithms for determining rankings for both keyword-based app store searches and composite top charts.

Unlike SEO, however, very little research and theory has been conducted around what goes into these rankings.

Until now, that is.

Over the course of five studies analyzing various publicly available data points for a cross-section of the top 500 iOS (U.S. Apple App Store) and the top 500 Android (U.S. Google Play) apps, I’ll attempt to set the record straight with a little myth-busting around ASO. In the process, I hope to assess and quantify any perceived correlations between app store ranks, ranking volatility, and a few of the factors commonly thought of as influential to an app’s ranking.

But first, a little context

Image credit: Josh Tuininga, Apptentive

Both the Apple App Store and Google Play have roughly 1.3 million apps each, and both stores feature a similar breakdown by app category. Apps ranking in the two stores should, theoretically, be on a fairly level playing field in terms of search volume and competition.

Of these apps, nearly two-thirds have not received a single rating and 99% are considered unprofitable. These studies, therefore, single out the rare exceptions to the rule—the top 500 ranked apps in each store.

While neither Apple nor Google have revealed specifics about how they calculate search rankings, it is generally accepted that both app store algorithms factor in:

  • Average app store rating
  • Rating/review volume
  • Download and install counts
  • Uninstalls (what retention and churn look like for the app)
  • App usage statistics (how engaged an app’s users are and how frequently they launch the app)
  • Growth trends weighted toward recency (how daily download counts changed over time and how today’s ratings compare to last week’s)
  • Keyword density of the app’s landing page (Ian did a great job covering this factor in a previous Moz post)

I’ve simplified this formula to a function highlighting the four elements with sufficient data (or at least proxy data) for our analysis:

Ranking = fn(Rating, Rating Count, Installs, Trends)

Of course, right now, this generalized function doesn’t say much. Over the next five studies, however, we’ll revisit this function before ultimately attempting to compare the weights of each of these four variables on app store rankings.

(For the purpose of brevity, I’ll stop here with the assumptions, but I’ve gone into far greater depth into how I’ve reached these conclusions in a 55-page report on app store rankings.)

Now, for the Mad Science.

Study #1: App-les to app-les app store ranking volatility

The first, and most straight forward of the five studies involves tracking daily movement in app store rankings across iOS and Android versions of the same apps to determine any trends of differences between ranking volatility in the two stores.

I went with a small sample of five apps for this study, the only criteria for which were that:

  • They were all apps I actively use (a criterion for coming up with the five apps but not one that influences rank in the U.S. app stores)
  • They were ranked in the top 500 (but not the top 25, as I assumed app store rankings would be stickier at the top—an assumption I’ll test in study #2)
  • They had an almost identical version of the app in both Google Play and the App Store, meaning they should (theoretically) rank similarly
  • They covered a spectrum of app categories

The apps I ultimately chose were Lyft, Venmo, Duolingo, Chase Mobile, and LinkedIn. These five apps represent the travel, finance, education banking, and social networking categories.

Hypothesis

Going into this analysis, I predicted slightly more volatility in Apple App Store rankings, based on two statistics:

Both of these assumptions will be tested in later analysis.

Results

7-Day App Store Ranking Volatility in the App Store and Google Play

Among these five apps, Google Play rankings were, indeed, significantly less volatile than App Store rankings. Among the 35 data points recorded, rankings within Google Play moved by as much as 23 positions/ranks per day while App Store rankings moved up to 89 positions/ranks. The standard deviation of ranking volatility in the App Store was, furthermore, 4.45 times greater than that of Google Play.

Of course, the same apps varied fairly dramatically in their rankings in the two app stores, so I then standardized the ranking volatility in terms of percent change to control for the effect of numeric rank on volatility. When cast in this light, App Store rankings changed by as much as 72% within a 24-hour period while Google Play rankings changed by no more than 9%.

Also of note, daily rankings tended to move in the same direction across the two app stores approximately two-thirds of the time, suggesting that the two stores, and their customers, may have more in common than we think.

Study #2: App store ranking volatility across the top charts

Testing the assumption implicit in standardizing the data in study No. 1, this one was designed to see if app store ranking volatility is correlated with an app’s current rank. The sample for this study consisted of the top 500 ranked apps in both Google Play and the App Store, with special attention given to those on both ends of the spectrum (ranks 1–100 and 401–500).

Hypothesis

I anticipated rankings to be more volatile the higher an app is ranked—meaning an app ranked No. 450 should be able to move more ranks in any given day than an app ranked No. 50. This hypothesis is based on the assumption that higher ranked apps have more installs, active users, and ratings, and that it would take a large margin to produce a noticeable shift in any of these factors.

Results

App Store Ranking Volatility of Top 500 Apps

One look at the chart above shows that apps in both stores have increasingly more volatile rankings (based on how many ranks they moved in the last 24 hours) the lower on the list they’re ranked.

This is particularly true when comparing either end of the spectrum—with a seemingly straight volatility line among Google Play’s Top 100 apps and very few blips within the App Store’s Top 100. Compare this section to the lower end, ranks 401–)500, where both stores experience much more turbulence in their rankings. Across the gamut, I found a 24% correlation between rank and ranking volatility in the Play Store and 28% correlation in the App Store.

To put this into perspective, the average app in Google Play’s 401–)500 ranks moved 12.1 ranks in the last 24 hours while the average app in the Top 100 moved a mere 1.4 ranks. For the App Store, these numbers were 64.28 and 11.26, making slightly lower-ranked apps more than five times as volatile as the highest ranked apps. (I say slightly as these “lower-ranked” apps are still ranked higher than 99.96% of all apps.)

The relationship between rank and volatility is pretty consistent across the App Store charts, while rank has a much greater impact on volatility at the lower end of Google Play charts (ranks 1-100 have a 35% correlation) than it does at the upper end (ranks 401-500 have a 1% correlation).

Study #3: App store rankings across the stars

The next study looks at the relationship between rank and star ratings to determine any trends that set the top chart apps apart from the rest and explore any ties to app store ranking volatility.

Hypothesis

Ranking = fn(Rating, Rating Count, Installs, Trends)

As discussed in the introduction, this study relates directly to one of the factors commonly accepted as influential to app store rankings: average rating.

Getting started, I hypothesized that higher ranks generally correspond to higher ratings, cementing the role of star ratings in the ranking algorithm.

As far as volatility goes, I did not anticipate average rating to play a role in app store ranking volatility, as I saw no reason for higher rated apps to be less volatile than lower rated apps, or vice versa. Instead, I believed volatility to be tied to rating volume (as we’ll explore in our last study).

Results

Average App Store Ratings of Top Apps

The chart above plots the top 100 ranked apps in either store with their average rating (both historic and current, for App Store apps). If it looks a little chaotic, it’s just one indicator of the complexity of ranking algorithm in Google Play and the App Store.

If our hypothesis was correct, we’d see a downward trend in ratings. We’d expect to see the No. 1 ranked app with a significantly higher rating than the No. 100 ranked app. Yet, in neither store is this the case. Instead, we get a seemingly random plot with no obvious trends that jump off the chart.

A closer examination, in tandem with what we already know about the app stores, reveals two other interesting points:

  1. The average star rating of the top 100 apps is significantly higher than that of the average app. Across the top charts, the average rating of a top 100 Android app was 4.319 and the average top iOS app was 3.935. These ratings are 0.32 and 0.27 points, respectively, above the average rating of all rated apps in either store. The averages across apps in the 401–)500 ranks approximately split the difference between the ratings of the top ranked apps and the ratings of the average app.
  2. The rating distribution of top apps in Google Play was considerably more compact than the distribution of top iOS apps. The standard deviation of ratings in the Apple App Store top chart was over 2.5 times greater than that of the Google Play top chart, likely meaning that ratings are more heavily weighted in Google Play’s algorithm.

App Store Ranking Volatility and Average Rating

Looking next at the relationship between ratings and app store ranking volatility reveals a -15% correlation that is consistent across both app stores; meaning the higher an app is rated, the less its rank it likely to move in a 24-hour period. The exception to this rule is the Apple App Store’s calculation of an app’s current rating, for which I did not find a statistically significant correlation.

Study #4: App store rankings across versions

This next study looks at the relationship between the age of an app’s current version, its rank and its ranking volatility.

Hypothesis

Ranking = fn(Rating, Rating Count, Installs, Trends)

In alteration of the above function, I’m using the age of a current app’s version as a proxy (albeit not a very good one) for trends in app store ratings and app quality over time.

Making the assumptions that (a) apps that are updated more frequently are of higher quality and (b) each new update inspires a new wave of installs and ratings, I’m hypothesizing that the older the age of an app’s current version, the lower it will be ranked and the less volatile its rank will be.

Results

How update frequency correlates with app store rank

The first and possibly most important finding is that apps across the top charts in both Google Play and the App Store are updated remarkably often as compared to the average app.

At the time of conducting the study, the current version of the average iOS app on the top chart was only 28 days old; the current version of the average Android app was 38 days old.

As hypothesized, the age of the current version is negatively correlated with the app’s rank, with a 13% correlation in Google Play and a 10% correlation in the App Store.

How update frequency correlates with app store ranking volatility

The next part of the study maps the age of the current app version to its app store ranking volatility, finding that recently updated Android apps have less volatile rankings (correlation: 8.7%) while recently updated iOS apps have more volatile rankings (correlation: -3%).

Study #5: App store rankings across monthly active users

In the final study, I wanted to examine the role of an app’s popularity on its ranking. In an ideal world, popularity would be measured by an app’s monthly active users (MAUs), but since few mobile app developers have released this information, I’ve settled for two publicly available proxies: Rating Count and Installs.

Hypothesis

Ranking = fn(Rating, Rating Count, Installs, Trends)

For the same reasons indicated in the second study, I anticipated that more popular apps (e.g., apps with more ratings and more installs) would be higher ranked and less volatile in rank. This, again, takes into consideration that it takes more of a shift to produce a noticeable impact in average rating or any of the other commonly accepted influencers of an app’s ranking.

Results

Apps with more ratings and reviews typically rank higher

The first finding leaps straight off of the chart above: Android apps have been rated more times than iOS apps, 15.8x more, in fact.

The average app in Google Play’s Top 100 had a whopping 3.1 million ratings while the average app in the Apple App Store’s Top 100 had 196,000 ratings. In contrast, apps in the 401–)500 ranks (still tremendously successful apps in the 99.96 percentile of all apps) tended to have between one-tenth (Android) and one-fifth (iOS) of the ratings count as that of those apps in the top 100 ranks.

Considering that almost two-thirds of apps don’t have a single rating, reaching rating counts this high is a huge feat, and a very strong indicator of the influence of rating count in the app store ranking algorithms.

To even out the playing field a bit and help us visualize any correlation between ratings and rankings (and to give more credit to the still-staggering 196k ratings for the average top ranked iOS app), I’ve applied a logarithmic scale to the chart above:

The relationship between app store ratings and rankings in the top 100 apps

From this chart, we can see a correlation between ratings and rankings, such that apps with more ratings tend to rank higher. This equates to a 29% correlation in the App Store and a 40% correlation in Google Play.

Apps with more ratings typically experience less app store ranking volatility

Next up, I looked at how ratings count influenced app store ranking volatility, finding that apps with more ratings had less volatile rankings in the Apple App Store (correlation: 17%). No conclusive evidence was found within the Top 100 Google Play apps.

Apps with more installs and active users tend to rank higher in the app stores

And last but not least, I looked at install counts as an additional proxy for MAUs. (Sadly, this is a statistic only listed in Google Play. so any resulting conclusions are applicable only to Android apps.)

Among the top 100 Android apps, this last study found that installs were heavily correlated with ranks (correlation: -35.5%), meaning that apps with more installs are likely to rank higher in Google Play. Android apps with more installs also tended to have less volatile app store rankings, with a correlation of -16.5%.

Unfortunately, these numbers are slightly skewed as Google Play only provides install counts in broad ranges (e.g., 500k–)1M). For each app, I took the low end of the range, meaning we can likely expect the correlation to be a little stronger since the low end was further away from the midpoint for apps with more installs.

Summary

To make a long post ever so slightly shorter, here are the nuts and bolts unearthed in these five mad science studies in app store optimization:

  1. Across the top charts, Apple App Store rankings are 4.45x more volatile than those of Google Play
  2. Rankings become increasingly volatile the lower an app is ranked. This is particularly true across the Apple App Store’s top charts.
  3. In both stores, higher ranked apps tend to have an app store ratings count that far exceeds that of the average app.
  4. Ratings appear to matter more to the Google Play algorithm, especially as the Apple App Store top charts experience a much wider ratings distribution than that of Google Play’s top charts.
  5. The higher an app is rated, the less volatile its rankings are.
  6. The 100 highest ranked apps in either store are updated much more frequently than the average app, and apps with older current versions are correlated with lower ratings.
  7. An app’s update frequency is negatively correlated with Google Play’s ranking volatility but positively correlated with ranking volatility in the App Store. This likely due to how Apple weighs an app’s most recent ratings and reviews.
  8. The highest ranked Google Play apps receive, on average, 15.8x more ratings than the highest ranked App Store apps.
  9. In both stores, apps that fall under the 401–500 ranks receive, on average, 10–20% of the rating volume seen by apps in the top 100.
  10. Rating volume and, by extension, installs or MAUs, is perhaps the best indicator of ranks, with a 29–40% correlation between the two.

Revisiting our first (albeit oversimplified) guess at the app stores’ ranking algorithm gives us this loosely defined function:

Ranking = fn(Rating, Rating Count, Installs, Trends)

I’d now re-write the function into a formula by weighing each of these four factors, where a, b, c, & d are unknown multipliers, or weights:

Ranking = (Rating * a) + (Rating Count * b) + (Installs * c) + (Trends * d)

These five studies on ASO shed a little more light on these multipliers, showing Rating Count to have the strongest correlation with rank, followed closely by Installs, in either app store.

It’s with the other two factors—rating and trends—that the two stores show the greatest discrepancy. I’d hazard a guess to say that the App Store prioritizes growth trends over ratings, given the importance it places on an app’s current version and the wide distribution of ratings across the top charts. Google Play, on the other hand, seems to favor ratings, with an unwritten rule that apps just about have to have at least four stars to make the top 100 ranks.

Thus, we conclude our mad science with this final glimpse into what it takes to make the top charts in either store:

Weight of factors in the Apple App Store ranking algorithm

Rating Count > Installs > Trends > Rating

Weight of factors in the Google Play ranking algorithm

Rating Count > Installs > Rating > Trends


Again, we’re oversimplifying for the sake of keeping this post to a mere 3,000 words, but additional factors including keyword density and in-app engagement statistics continue to be strong indicators of ranks. They simply lie outside the scope of these studies.

I hope you found this deep-dive both helpful and interesting. Moving forward, I also hope to see ASOs conducting the same experiments that have brought SEO to the center stage, and encourage you to enhance or refute these findings with your own ASO mad science experiments.

Please share your thoughts in the comments below, and let’s deconstruct the ranking formula together, one experiment at a time.

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Has Google Gone Too Far with the Bias Toward Its Own Content?

Posted by ajfried

Since the beginning of SEO time, practitioners have been trying to crack the Google algorithm. Every once in a while, the industry gets a glimpse into how the search giant works and we have opportunity to deconstruct it. We don’t get many of these opportunities, but when we do—assuming we spot them in time—we try to take advantage of them so we can “fix the Internet.”

On Feb. 16, 2015, news started to circulate that NBC would start removing images and references of Brian Williams from its website.

This was it!

A golden opportunity.

This was our chance to learn more about the Knowledge Graph.

Expectation vs. reality

Often it’s difficult to predict what Google is truly going to do. We expect something to happen, but in reality it’s nothing like we imagined.

Expectation

What we expected to see was that Google would change the source of the image. Typically, if you hover over the image in the Knowledge Graph, it reveals the location of the image.

Keanu-Reeves-Image-Location.gif

This would mean that if the image disappeared from its original source, then the image displayed in the Knowledge Graph would likely change or even disappear entirely.

Reality (February 2015)

The only problem was, there was no official source (this changed, as you will soon see) and identifying where the image was coming from proved extremely challenging. In fact, when you clicked on the image, it took you to an image search result that didn’t even include the image.

Could it be? Had Google started its own database of owned or licensed images and was giving it priority over any other sources?

In order to find the source, we tried taking the image from the Knowledge Graph and “search by image” in images.google.com to find others like it. For the NBC Nightly News image, Google failed to even locate a match to the image it was actually using anywhere on the Internet. For other television programs, it was successful. Here is an example of what happened for Morning Joe:

Morning_Joe_image_search.png

So we found the potential source. In fact, we found three potential sources. Seemed kind of strange, but this seemed to be the discovery we were looking for.

This looks like Google is using someone else’s content and not referencing it. These images have a source, but Google is choosing not to show it.

Then Google pulled the ol’ switcheroo.

New reality (March 2015)

Now things changed and Google decided to put a source to their images. Unfortunately, I mistakenly assumed that hovering over an image showed the same thing as the file path at the bottom, but I was wrong. The URL you see when you hover over an image in the Knowledge Graph is actually nothing more than the title. The source is different.

Morning_Joe_Source.png

Luckily, I still had two screenshots I took when I first saw this saved on my desktop. Success. One screen capture was from NBC Nightly News, and the other from the news show Morning Joe (see above) showing that the source was changed.

NBC-nightly-news-crop.png

(NBC Nightly News screenshot.)

The source is a Google-owned property: gstatic.com. You can clearly see the difference in the source change. What started as a hypothesis in now a fact. Google is certainly creating a database of images.

If this is the direction Google is moving, then it is creating all kinds of potential risks for brands and individuals. The implications are a loss of control for any brand that is looking to optimize its Knowledge Graph results. As well, it seems this poses a conflict of interest to Google, whose mission is to organize the world’s information, not license and prioritize it.

How do we think Google is supposed to work?

Google is an information-retrieval system tasked with sourcing information from across the web and supplying the most relevant results to users’ searches. In recent months, the search giant has taken a more direct approach by answering questions and assumed questions in the Answer Box, some of which come from un-credited sources. Google has clearly demonstrated that it is building a knowledge base of facts that it uses as the basis for its Answer Boxes. When it sources information from that knowledge base, it doesn’t necessarily reference or credit any source.

However, I would argue there is a difference between an un-credited Answer Box and an un-credited image. An un-credited Answer Box provides a fact that is indisputable, part of the public domain, unlikely to change (e.g., what year was Abraham Lincoln shot? How long is the George Washington Bridge?) Answer Boxes that offer more than just a basic fact (or an opinion, instructions, etc.) always credit their sources.

There are four possibilities when it comes to Google referencing content:

  • Option 1: It credits the content because someone else owns the rights to it
  • Option 2: It doesn’t credit the content because it’s part of the public domain, as seen in some Answer Box results
  • Option 3: It doesn’t reference it because it owns or has licensed the content. If you search for “Chicken Pox” or other diseases, Google appears to be using images from licensed medical illustrators. The same goes for song lyrics, which Eric Enge discusses here: Google providing credit for content. This adds to the speculation that Google is giving preference to its own content by displaying it over everything else.
  • Option 4: It doesn’t credit the content, but neither does it necessarily own the rights to the content. This is a very gray area, and is where Google seemed to be back in February. If this were the case, it would imply that Google is “stealing” content—which I find hard to believe, but felt was necessary to include in this post for the sake of completeness.

Is this an isolated incident?

At Five Blocks, whenever we see these anomalies in search results, we try to compare the term in question against others like it. This is a categorization concept we use to bucket individuals or companies into similar groups. When we do this, we uncover some incredible trends that help us determine what a search result “should” look like for a given group. For example, when looking at searches for a group of people or companies in an industry, this grouping gives us a sense of how much social media presence the group has on average or how much media coverage it typically gets.

Upon further investigation of terms similar to NBC Nightly News (other news shows), we noticed the un-credited image scenario appeared to be a trend in February, but now all of the images are being hosted on gstatic.com. When we broadened the categories further to TV shows and movies, the trend persisted. Rather than show an image in the Knowledge Graph and from the actual source, Google tends to show an image and reference the source from Google’s own database of stored images.

And just to ensure this wasn’t a case of tunnel vision, we researched other categories, including sports teams, actors and video games, in addition to spot-checking other genres.

Unlike terms for specific TV shows and movies, terms in each of these other groups all link to the actual source in the Knowledge Graph.

Immediate implications

It’s easy to ignore this and say “Well, it’s Google. They are always doing something.” However, there are some serious implications to these actions:

  1. The TV shows/movies aren’t receiving their due credit because, from within the Knowledge Graph, there is no actual reference to the show’s official site
  2. The more Google moves toward licensing and then retrieving their own information, the more biased they become, preferring their own content over the equivalent—or possibly even superior—content from another source
  3. If feels wrong and misleading to get a Google Image Search result rather than an actual site because:
    • The search doesn’t include the original image
    • Considering how poor Image Search results are normally, it feels like a poor experience
  4. If Google is moving toward licensing as much content as possible, then it could make the Knowledge Graph infinitely more complicated when there is a “mistake” or something unflattering. How could one go about changing what Google shows about them?

Google is objectively becoming subjective

It is clear that Google is attempting to create databases of information, including lyrics stored in Google Play, photos, and, previously, facts in Freebase (which is now Wikidata and not owned by Google).

I am not normally one to point my finger and accuse Google of wrongdoing. But this really strikes me as an odd move, one bordering on a clear bias to direct users to stay within the search engine. The fact is, we trust Google with a heck of a lot of information with our searches. In return, I believe we should expect Google to return an array of relevant information for searchers to decide what they like best. The example cited above seems harmless, but what about determining which is the right religion? Or even who the prettiest girl in the world is?

Religion-and-beauty-queries.png

Questions such as these, which Google is returning credited answers for, could return results that are perceived as facts.

Should we next expect Google to decide who is objectively the best service provider (e.g., pizza chain, painter, or accountant), then feature them in an un-credited answer box? The direction Google is moving right now, it feels like we should be calling into question their objectivity.

But that’s only my (subjective) opinion.

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