How Accurate Are Website Traffic Estimators?
If you’ve worked at an agency for any significant amount of time, and particularly if you’ve been involved in forecasting, proposals or client pitches, you’ve likely been asked at least one of (or a combination or amalgamation of) the following questions:
- 1) How much traffic can I expect to receive?
- 2) How long until I see X amount of organic visits?
- 3) What traffic will I receive from X investment?
- 4) What organic opportunity is available within our industry?
- 5) How much traffic do my competitors receive?
Forecasting is notoriously difficult, and done badly can be misleading or even damaging. There is a myriad of assumptions, caveats and uncontrollable factors that can mean that any predictions are nothing more than a
finger in the air educated estimation. Organic forecasting is difficult enough to do, that writing about and explaining it would give me sleepless nights (Kirsty Hulse wrote a better post than I ever could on the subject), so I decided to focus on questions 4 and 5 of those listed above.
Imagine this very realistic (or even familiar) scenario; a client wants to know how much traffic their competitor receives, what the potential size and opportunity of their vertical is, and how to fulfil that potential by increasing visibility and acquiring more traffic. Before being able to accurately and insightfully answer the trickier final point there, it would be useful to know what you’re competing against. Assuming you don’t have access to your client’s competitors’ analytics data, it would be useful to get an idea of their organic performance, and ideally have confidence that the data you’re looking at is at best solid.
There are a number of really great visibility tools we use at Screaming Frog (Searchmetrics and Sistrix to name a couple of favourites), but these tools choose not to speculate on traffic, instead estimating visibility based on ranking position and keyword volume/value (which doesn’t necessarily correlate to traffic). There are a number of traffic estimator tools which obviously do speculate on traffic, as well as some well-known SEO tools that have functionality or components within their suites that do the same, which got us wondering a few things;
We wanted to put their accuracy to the test, so here’s what we did:
1) We took organic visit data for a range of 25 websites we have access to via Google Analytics, for the months of February, March and April 2016 (January can often be an outlier for many websites, so we just selected the most recent 3-month period of relative stability). We looked exclusively at UK organic traffic only (generally, but not exclusively the 25 sites selected are primarily UK focused, but some target multiple territories or even worldwide), because some of the traffic estimator tools segment traffic by region, and don’t always cover every territory. Similarly, not all the tools we used in the test deal especially well with subdomains, so we selected root domains in our analysis.
2) While we can’t disclose the websites selected, to ensure as even a test as possible within what is a fairly small sample size, we specifically selected sites that covered a range of verticals, target audiences and purposes (more on that breakdown to come). For the same reason, we also selected sites that covered a range of different traffic levels, from those which receive millions of organic visits each month, to those with just hundreds of visits. We hoped this varied selection might show trends where certain tools are more or less accurate at estimating certain types of websites’ traffic levels.
3) We analysed these 25 websites using 3 tools – SimilarWeb, Ahrefs and SEMrush. We recorded organic traffic estimate numbers for each of the 25 websites, focusing on exclusively UK traffic to match up with our GA data.
4) We measured actual traffic against estimated traffic for each of the 3 tools. We measured this in a number of different ways –
a. Visits difference for each site using each tool.
b. Percentage of visits difference for each site using each tool.
c. Overall visits difference for each tool.
d. Percentage of visits difference for each tool.
e. Average percentage difference for each tool.
Before sharing the results I’ll share my one real prediction; the tools would almost certainly underestimate organic traffic. This is because these traffic estimator tools have limited indexes and only track a certain amount of keywords, so can’t possibly expect to completely accurately estimate traffic. Most don’t handle the long tail well as they simply don’t have the keyword bandwidth to do so. Furthermore, the tools, much like standard forecasting CTR modelling, also assume visit numbers by ranking position of keyword volume – they *don’t* consider keyword intent, brand vs non-brand, Google answer boxes, 9-pack & 7-pack results, the Knowledge Graph etc.
You can access the data here.
Our test is by no means a thorough mathematical or scientific experiment, merely a quick test to try and gauge the accuracy of such tools. There are a number of ways we could improve or increase our test, including but not limited to:
Our rather limited test is just the tip of the iceberg, but has hopefully shown that all traffic estimators have strengths and weaknesses, and their level of accuracy can vary quite considerably.