Today we're going to break down a number of different tools and resources for getting insights into competitors traffic data. We have looked at a handful of tools here and will break them down one by one as to their strengths and weaknesses, as well as the validity and usefulness of the data provided. Ultimately we just wanted to share with you some other information sources out there that you can add to SEOmoz's list of tools that are great for competitor analysis (my personal favourites being the Linkscape Visualization and Comparison tool as well as the Competitive Link Research tool).

However, I have had a number of clients asking me for a better view of overall market size and what kind of traffic their competitors are getting. Despite the fact that this has, unfortunately, at times meant crushing a few dreams about who a genuine/realistic competitor is or should be (i.e. NOT mashable if you are a new site) it can be tricky to find meaningful predictive data even when you know who your competitors are.

The Failed Experiment

Initially I wanted this to be an experiment testing out a number of services and running them against Analytics data to compare like for like and find which sites provided the most accurate information. I compiled Analytics data from 25 websites with hopes of comparing the real numbers (from Analytics) against the predictions of the other tools to try to find which was the most reliable across a number of sites from different sectors with a range of monthly traffic from ~1,000 monthly visitors to over 48,000,000 monthly visitors.

The idea was to report on data across a number of these platforms for average monthly visits, total yearly visits, geographical visits and so forth. Unfortunately, there were many fewer tools that provided this data than I initially anticipated and it quickly became clear that we weren't going to be able to compare apples to apples and there is no substitute for internal data... but through the combination of some of the below tools you can get a good idea of what sort of traffic your competitors sites are getting.

So, the experiment was a bit of a failure, but I learned more than my fair share about the tools so let's have a look at which tools are available and which tasks/comparisons they can be used for. I'm hanging on to all the data I collected and at a future date (if I ever hear back from some of the data sources) I will post a follow-up/re-do of the experiment.

The Tool Belt

It is worth pointing out that a number of these sites suggest they can provide better data if you claim the site(s) in question. I cannot testify to the accuracy of this because we have not looked into this (and could not feasibly claim the data for all 25 sites), also, all comments are based upon the free version of the tools as we did not have paid access to any of the tools.

Alexa

Strengths:
Alexa is good for comparing different sites traffic and for monitoring general traffic trends. It can be quite useful for comparing one site to a competitor site (up to 5 sites at a time).
The index is massive and contains some data about all of the 25 sites we tested.

Weaknesses:
Not so great for the smaller sites. As you can see below, you won't get any of the traffic charts for sites ranked outside of the top 100,000 (which means if you Alexa thinks you are getting any fewer than 10,000 visits per month you're unlikely to glean any great information.

Accuracy is a serious concern. This does taint the usefullness of the tool in general.

The numbers reported are not helpful for predicting traffic on their own.

Accuracy:

We want to keep this all anonymous but let's just say one site that we know gets 10-20,000 visits per month had an Alexa rank that was more than 5 times better than a site that we know gets 75,000+ visitors per month. And this was not just a one-off event.

I would have to seriously quetsion the reliability of this tool. It didn't seem to be too bad at predicting the trends for a single site but the charts are extremely difficult to make any real use of. The information on bounce rate seems fairly accurate (give or take a few percent) but the trends for bounce rate seemed much less accurate (e.g. the ups and downs did not seem to correspond with similar peaks and valleys in Analytics).

Perhaps most interestingly it seems to be skewed in favour of sites within the search marketing space. Sites in the search marketing space that we looked at regulary outranked sites receiving more than 10 times as much traffic on a monthly basis.

How to best use Alexa?
The tool is interesting for comparing similar sites or sites within an industry. I would like to recommend the tool but based upon my experience and this particular data set I would have to say I would be very cautious about using this to make any meaningful suggestions or estimates on traffic data. It is a great concept for a site but does not seem to have been particularly accurate.

The most accurate data seemed to be the data from the visitors by country (the order was fairly accurate and the percentages we looked at were not to far off). To the extent that this data would be useful to have for your competitors this would be one good use of Alexa data.

The insights for audience demographics could also potentially be extremely valuable, though accuracy will always be a question.

Cost:
Free. Options for site audits for $199
 

Compete

Strengths:
Useful interface.
Speak the right language (unique visitors, visits, etc).
Ability to compare multiple sites
Data is easy to understand and well presented.

Weaknesses:
Accuracy
Somewhat limited number of sites - many sites that it classifies as "low sample sites"
Cost of "Pro" option  

Accuracy:
Again, accuracy is a serious concern here. The data was off in some cases by as much as 2,000% for monthly visits. The accuracy seemed to be a bit better for the peaks in traffic and some of the general trends we looked at, but was certainly not reliable enough for us to suggest reporting competitor traffic based upon this information.  

How to best use Compete?
It should come as no surprise that Compete is best used for comparing competitors. The scale of the data is way off but some of the trends seemed to be fairly reliable. I wouldn't advise reporting any numbers from this data (as they do not seem close/reliable at all - often off by a factor of 2 or more), however the trends are reliable. The information could be meaningfully used to look into seasonal trends between competitors. The demographic information (again, not being able to comment on the accuracy) would also be quite interesting but would require registering your site.

I can't very well recommend the PRO services as I was not able to gain access and was unwilling to pay the cost just for the blog post. I would be extremely interesting in looking further into some of the referral data and the keywords data but this is not available as part of the standard free toolset.

Cost: Free. The PRO membership is $499 per month.
 

ComScore

Unfortunately we struggled with ComScore. We were unable to get a login or sneak a peak at any of the data. Thus, obviously we cannot comment on the validity of the data, only some of the offerings.

Strengths:
N/A

Weaknesses:
N/A

Accuracy:
N/A

Best use of ComScore:
ComScore offers a number of reports and insights into markets including reports on Local market size, as well as information about valuable/important keywords in an industry. It would be very interesting to find out where this data was coming from and how good it was, but we were not able to achieve this in time to publish this information.

Cost: N/A
Costs were not listed on the site, but rather suggest contacting ComScore directly.

Google Ad Planner

Strengths:
Sites also visited data is good
Keywords searched for can be quite valuable
Audience interests data interesting
 

Weaknesses:
Accuracy
Lack of data for small sites

Accuracy:
The accuracy was really mixed. For many of the sites AdPlanner provided much better data than some of the others, however, they were still off by miles for some sites - off by as much as 1000%. Again, the data on this in general tended to be better than many of the others, but given the occassional "big miss" I would not be comfortable using this data to make traffic predictions for a client.

How to best use Google Ad Planner:
The data about other sites visited as well as keywords searched for (with affinity) could be extremely valuable. As well as some of the other metrics reported on and audience interests. However, the traffic data is not particularly meangingful and is not to be relied upon.

Pro-tip: The data tends to be better when site owners have granted permission to analytics to publish data, I know we all love open and friendly, but this isn't the sort of thing you neccessarily want to make easier for your competitors to find.

Cost: Free.

Google Insights

Strengths:
Trends around Keyphrases and keyphrase groups
Regional information
Trusted source

Weaknesses:
Difficult to read the data
No hard and fast numbers about traffic
Hard to compare entire sites to one another

Accuracy:
You can bet that the accuracy of this data is going to be pretty good given that the data provider has access to more data than anyone else on the internet. However, the fact that the numbers are normalised and more designed for keyphrases and search terms and trends than for traffic data means that the search volume will correspond perfectly with the traffic to a site.

How to best use Google Insights:
Google Insights could be quite helpful for finding the most valuable pockets of keyphrases and keyphrase groups. This could be particularly valuable when looking at a competitor site and trying to figure out which of their keyphrases are driving the most traffic. Further to that point, it could help you see which of the keyphrases within a keyphrase group might be the most valuable.

Cost: Free.
 

Google Trends for Websites

Strengths:
Good for illustrating magnitudes of difference between sites
Allows comparison of multiple websites
Includes regional information

Weaknesses:
Not good for comparing sites fairly similar in size
Does not have information for smaller sites when logged in
Accuracy imperfect
No numbers*

Accuracy:
The data seems to be more accurate when only trying to compare traffic from search, it does not seem to do as well in picking the winning recipient of overall traffic. Given that these trends are Google Trends this is reasonable and still paints a fair landscape for an SEO's needs.

When comparing websites with drastically different traffic numbers the rough visual estimation appears to correspond quite well with the observed analytics data as well.

It's a shame there are no actual numbers for the data, but that would just be too easy.
 

How to best use Google Trends for Websites?
Trends is great for broad information gathering. It gives some insite into similar searches when comparing sites, and in general it is unlikely that you will find better comparative data out there without direct access to your competitor's analytics account. However, Trends does not provide numbers and thus can only be used to venture a guess at what sorts of numbers competitors are pulling in.

When two sites are relatively similar in size Google Trends does not always pick the winner in terms of monthly traffic correctly. For example, one of the sites we tested received around 7.5m monthly visits whilst another received around 8m and Google ranked the 7.5m website higher. However, it is worth noting that the 7.5m visitor site received considerably more volume from search than did the 8m visitor site so from an SEO standpoint this data is probably quite accurate.

Edit 22/11/2010 at 13:47 GMT:

Thank you very much to Jest for pointing out that this information was originally written and summarised when logged out of Google. When visiting the site logged in it does provide data (i.e. numbers/ranges). This information makes the tool considerably more valuable. I must point out that I have not had time to run this across the entire data set, though it is worth pointing out that even with the information the data looks to be off on a few of the sites I have checked. It is not as far off as the data for the same sites using AdPlanner, but still considerably far off (e.g. reporting 140k visits for a site that receives ~320k unique visits daily).

HitWise

Unfortunately we were not able to get data from HitWise in time. The HitWise team was very helpful, responsive and agreeable and we will share this data once we have gotten our hands on it. However, we had not received the data back on the websites in the study in time for publication.

Strengths:
N/A

Weaknesses:
N/A

Accuracy:
N/A

Best use of HitWise:
HitWise, similarly to comScore works on a reporting basis insofar as you speak to them about the types of market reports you would like or you can create custom reports. Whilst we obviously cannot comment on the accuracy of the data the services offered look to be better tailored to an SEOs needs than do the reports offered by comScore. However, generally speaking HitWise will not work with agencies which will be a bit of a bummer for some of you.

Cost: Free-$695+ per report
The range in cost seems to be fairly large. Whether the data warrants the pricing structure cannot really be judged without looking at the data, though they do make some data freely available through their website.

Quantcast

Strengths:
Traffic Numbers that are easy to follow
Design and display of information
Demographic information (when available)
Media Planner Tool

Weaknesses:
Unreliable
Lacks data for small-medium trafficked sites
Accuracy
Inability to compare sites

Accuracy:
Definitely the biggest shortcoming of the Quantcast data is accuracy. As with some of the other sources the traffic data is estimated and is nowhere near accurate on the sites for which Quantcast had any data. Data was off by as much as 10 times the actual analytics data for some of the sites. Again, I cannot say that I would recommend sharing any of the data with a client as an accurate predictor of a competitor's traffic.

Best Use of Quantcast:
Although the data is not particularly reliable for the traffic data some of the other tools the site has to offer seem quite interesting and worth further investigation. The demographics information is also particularly interesting because it provides a reference as to how the data compare against the internet average. This sort of data could be particularly valuable for analysing a market by compiling data across multiple sites.

Cost: Free.
 

SEMrush

Strengths:
Data Includes sites of all sizes
List of Keyphrases and rankings for thos terms
Most accurate numbered data of all tools looked at

Weaknesses:
Data imperfect
Pay to get full data lists
Data only for Google traffic

Accuracy:
The data was not perfectly accurate, though generally speaking SEMrush did not miss the mark for any of the sites we tested the same way a number of the other tools did. This is, obviously not to say that this data is infallible or that there won't be some issues with some sites, but the data was surprisingly accurate. As with some of the Google data the information reported is just the Google SE traffic, but this is our main area of focus and was quite accurate when drilling down into that specific area of traffic within analytics.

Best Use of SEMrush:
Although imperfect, this tool came the closest to providing accurate data that I would at least with a word of warning, be willing to share with a client about potential expectations or about where there competitors may be traffic wise. Most importantly, the add-on options and ability to see the keyword lists and how the competitor ranks for these terms is extraordinarily appealing to me.

Cost: Free-$499 per month

Conclusion

I hope that the findings from all this research will be valuable to you. At the end of the day it is an incomplete study and I look forward to following up on it when I have another big chunk of time and if/when I get access to comScore, HitWise, Compete PRO and SEMrush Pro. For the time being I would rely most heavily on SEMrush for predicting traffic and estimating how well a competitor is doing, but all of these tools add something to the ever growing toolbelt even if it may be for a purpose other than that which I was hoping they would achieve for me - we all know I love to misuse tools and I'm sure I will come up with some creative ways to use these insights.

Thanks a lot and look forward to any feedback you might have in the comments below or feel free to contact me on Twitter.