$)$ A retail company tries to determine whether a new feature on their mobile app is

effective in increasing user engagement. As a data analyst of the company, you want

to design an AIB test for this purpose. In your design, include the following:

$$ Define the treatment, subject, control and treatment groups, conversion, and

metric that is appropriate for this test.

$$ Describe the steps that should be taken in order to conduct the test.

$$ Describe the method to determine the sample size, if you want to have a high

probability $($i$.$e$.80\%)$ that you will be able to detect any significant

improvement in user engagement. State the factors involved in this method.