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# Does who answered the questions effect what formula to use?

Posted on 2012-08-22

Hi Experts!

This has been bugging me for years so I thought I'd see if I could get a definitive answer here. I have three scenarios. I ask questions about whether respondents like two products using a 10 point scale. There are three samples:

1) 200 people are asked both questions ("Do you like product A" & "Do you like product B")

2) 75 people are asked question one ONLY, 75 people are asked question two ONLY and 50 people are asked both questions

3) 100 people are asked question one ONLY, 100 people are asked question two ONLY

If I want to know if there is a significant difference between the mean of the answer to question one and the mean of the answer to question two, do I use the same formula to stat test these three samples?

Thanks!