A CRO hypothesis is basically a running idea about what hasn't changed and how to fix it. This is where the data you collect with Analytics or customer feedback comes from. Once you have this data, you state your hypothesis as follows:
We think that changing [item on page] for [Audience] will [get the desired result].
For example, you could say: We think that changing the text on the call-to-action button for web visitors will result in 100 new subscribers to our newsletter each month.
Success measurement A detailed hypothesis also includes how you will measure success. That means looking at data collected and customer feedback before and after the change to see if the situation has improved.
For the example above, you can look at average email subscribers in the past and see how it has changed after running your conversion tests.