Can you tell us more about the experiment you want to run? If so I
could give you some ideas on whether or not this would work.
-erik
On Mon, Oct 12, 2009 at 5:46 PM, jonathan <jrick...@gmail.com> wrote:
>
> I guess my question is more about: how do I make decisions based on
> the experiment results? I can't really tell from the example report
> how I would make a decision. Do the results say (to someone like me)
> "this experiment was a success/failure"? or are they more subtle?
>
> j
>
> On Oct 9, 12:56 am, Erik Wright <e...@erikwright.com> wrote:
...
>> An example report is shown on slide 11 of this prez:http://www.slideshare.net/erikwright/djangolean-akohas-opensource-ab-...
>>
>> In addition to that report, a similar report is shown per day of the
>> experiment.
You may need to take the time to "get your head around the
statistics". Quantative results without understanding what the
numbers mean can be dangerous or misleading.
In a report, as shown in his slide 11, for a given experiment, there
are two numbers that need to factor into your decision-- improvement,
and confidence. Improvement is the observed difference in the
measured metric. Confidence is how certain you can be that the
observed difference is not down to random chance. Basically, for
small differences, you need more observed data to be as confident as
you would be in a large observed difference.
For a thorough introduction to the math, see here:
http://elem.com/~btilly/effective-ab-testing/
The Xs are there to hide confidential information. The screenshot is
from an actual experiment run by Akoha.
The report shows the number of users in each test / control group.
For each conversion goal you will see:
1) the absolute number of users who hit it one or more times, per test/
control group
2) that number, as a percentage of the number of users in the group
3) the ratio between the performance of the test and control groups
4) the likelihood that the difference is "significant" as calculated
using a two-tailed chi-square test.
You will also see those values for "any" goal (count of users havin
achieved at least one goal one or more times).
Those numbers are shown for every day the experiment has been active.
With regards to confidence, the simple explanation is that 95% is
good. But the number should only be trusted once you have at least 10
conversions in both your test and control groups. At some point the
tool itself should be modified to reflect that.
Hope that helps,
Erik