# sample size for regression analysis

#### godfather

##### New Member
How would I determine the sample size needed for doing a study using continuous variables (3) and two dichotomous variables? This is for a proposal so I have not collected nay data. Is using prior research as a basis adequate?

#### JohnM

##### TS Contributor
Yes, you can use prior studies, if your study will be very similar, and the prior studies established that their sample sizes were "large enough" to evaluate the research questions.