Tell me more ×
Cross Validated is a question and answer site for statisticians, data analysts, data miners and data visualization experts. It's 100% free, no registration required.
up vote 0 down vote favorite

I'd like to know how to calculate the sample size needed for comparing the "change from baseline" scores between two groups?

Thank you in advance for your consideration

share|improve this question
1  
More information will be required to answer this question. Specifically, how variable are the scores within each of the groups and/or what kinds of numbers are these? Normally distributed continuous numbers? % correct? – Russell S. Pierce Jan 21 at 14:13

1 Answer

up vote -1 down vote

If the variable you are measuring is normally distributed, then you have two sets of measurements (one set of measurements at baseline, one set at some time point thereafter) that are related since they were obtained on the same objects/units (i.e. people). Thus you can use a t-test for dependent samples. There are many tutorials that will give you the formula for calculating your sample size.

share|improve this answer
The question does not provide much information but clearly states that the comparison of interest is between two groups. I don't see how a dependent sample T-test is useful in this situation. – Gaël Laurans Apr 21 at 20:04

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.