[Q] Survey on comedy in the Classroom – support on statistical sizes needed

Years ago, I worked in survey design and implementation. After many years away and doing other types of research, I now have another opportunity to pursue a new project. However, I’m getting increasingly nervous as I look into the nuts and bolts of making it happen.

I’ve always had a statistician help run my numbers and analysis in the past, which is no longer an option. Now, as I start my planning, I’m starting to worry. I hope that I can describe where I’m starting from and, based on your experience, get some advice about what things I should look out for, the potential types of analysis I should run, or any similarly modelled projects I can look at to for inspiration.

Here’s the breakdown:

1) My research investigates whether comedic examples aid in students’ ability to understand and reflect on experiences out in the community.

–I have a list of students who have agreed to further contact for research projects. –These students have taken a particular type of experiential course at the university, so they are not representative of the whole student body.

–Of the approximately 1,500 students who took this opportunity, approximately 550 have agreed to receive follow-up surveys.

–My question here is: how do I conceptualize, calculate, and articulate a representative sample?

2) I plan to compare the means of two different groups , so I am struggling to understand an appropriate population standard deviation.

–The survey will be approximately 20 questions long. Respondents will be randomly split into two groups. Each group will see a different video clip but will be asked identical questions after the clip. I want to compare the results of each question to see if there are significant differences.

–What is the sample size of each group needed to make these viable? I’m okay with a 90% confidence level.

–Does it then make the most sense to complete an independent group T-test for those differences?

While there is much more to consider, these two things are my initial stumbling blocks. Thanks in advance for any help or insight. It’s much appreciated.