Measuring Usability: Conversion Rate
Last week, I wrote about how you can gather clues about your website usability from your analytics package. It's a good starting point, and will help you establish some benchmarks, but the next step is to start thinking about your goals. What does usability success look like? In the world of website usability, the gold standard has become something we like to call the Conversion Rate (CR).Simply put, the Conversion Rate is just a measure of how many visitors convert into buyers, where "buyers" can be loosely defined to mean people who engage in any target activity, including making a purchase, filling out a contact form, downloading a document, etc. If you're operating a commercial website, you have an action you want people to take, and the role of strategic usability is to make it as easy as possible for them to take that action.
The Long Version
Of course, that's just the quick and dirty definition. Technically, conversion rate is the ratio of conversions to visitors, represented by a percentage. Let's say you're tracking actual online buyers of a product. If, in a given month, your website had 5,000 visitors and 125 of them purchased a product, your conversion rate for that month would be 2.5% (125/5000).
A couple of details that I think are worth mentioning. When pulling the visitor side of the equation from analytics, I generally prefer Unique Visitors. It may inflate your CR slightly, but for tracking over time, it's a much less noisy number than overall visitors. For conversions, you may have to look outside of your analytics, although many packages are starting to support tracking conversions/goals. If you have a commercial website, you probably already have a mechanism to track purchases. Bear in mind that you want to measure the total number of visitors who converted, not how many purchases they made (i.e. one person buying 14 items is still just one conversion).
Tracking Changes in CR
Like any measurement, as soon as you start tracking CR, you're probably going to get a bit carried away. Let me try to head that off with some advice. First, as with just about any website statistic, try to track changes over longer time periods. Comparing daily numbers is an exercise in futility. Personally, I like to track both weekly and monthly numbers (separately). Note that some analytics packages compute unique visitors differently depending on the time period, so only compare like time periods (months to months and weeks to weeks).
Just as importantly, let me share the mantra my experimental psychology professors drilled into me: "correlation does not imply causation". If you change something on your website, and CR goes up or down, don't assume it's because of what you did. Just like overall traffic, many factors can effect conversions, including weekends and holidays, consumer confidence, marketing campaigns, etc.
Hard-core Conversion Tracking
So, how do you determine if changes to your website actually do have an impact on conversions? For that, you're going to need to run an experiment, using something we like to call the A/B or "split" test. Next week, I'll talk a bit about the basics of split testing.
Sean
· Thursday, September 13I've always looked at the conversion tool and saw the general usefulness of it but never quite sure how it applied to my projects. As a blogger-type, I rely upon comments or registered users, but those are rare. I was thinking about splitting articles test to see if people are clicking through to the full article, but that seems to be creating an annoyance just for the purpose of metrics.
Dr. Pete
· Thursday, September 13From a blog standpoint, unless you're trying to drive some sort of information request or download, the only real conversion is probably whether or not someone subscribes to your feed. It would be interesting, now that I think about it, to get a handle on which posts convert the most readers to subscribers.
That might give you a better handle on what your audience is really interested in, which is hard to sort out. The only real metric we have is comments, and I've noticed that, just like on online communities, the really thought out, detailed and potentially useful posts often get fewer comments than the lighter posts. That's not a reflection on the post itself, but on the ability of the reader to easily chime in.
John S. Rhodes
· Saturday, September 15In my mind, conversion rate is more than this:
"Simply put, the Conversion Rate is just a measure of how many visitors convert into buyers, where "buyers" can be loosely defined to mean people who engage in any target activity, including making a purchase, filling out a contact form, downloading a document, etc."
Instead, it must be thought of in reference to, or as, a process. There are many steps from when the buyer first thinks about something they might want to the end point where they execute.
In the case of a mail message, it needs to be sent, it needs to reach the potential buyer, it needs to be opened, it needs to be read, a link needs to be clicked, a sales letter needs to be read, an order button needs to be clicked, the purchase cannot be abandoned, and the credit card needs to be pulled out and used, to complete the conversion.
~ John
Dr. Pete
· Saturday, September 15That's a good point, John. I was thinking more narrowly about Conversion Rate as a metric, but "conversion" is definitely a process made up of many choices, and each of those choices raises important questions of usability (and can potentially be analyzed for weak points).