Quantifying the User Experience: Practical Statistics for User Research
Let’s assume that you want a 95 percent confidence in your answer. This corresponds to a Z-score of 2, meaning that the number must fall within two standard deviations of the observed mean.
Maura Ginty • Landing Page Optimization: The Definitive Guide to Testing and Tuning for Conversions
For example, the expected value for SN1 on the attribute to relieve boredom is calculated in the following way: To get the deviation from the expected scores we subtract the actual (128) from the expected (111) = 17, divide this total by the sample size (205) and multiply by 100 = ((17/205)*100) = +8 percentage point (pp) mental advantage for SN1 o
... See moreJenni Romaniuk • Better Brand Health eBook
there can (and should) be short-term streaks that significantly skew the conversion rates in low data situations. Remember, the laws of probability only guarantee the accuracy and stability of results for very large sample sizes. For smaller sample sizes, a lot of fuzz and uncertainty remain.
Maura Ginty • Landing Page Optimization: The Definitive Guide to Testing and Tuning for Conversions
Typically, usability is measured relative to users' performance on a given set of test tasks. The most basic measures are based on the definition of usability as a quality metric:
- success rate (whether users can perform the task at all),
- the time a task requires,
- the error rate, and
- users' subjective satisfaction.