Determining sample size from confidence interval and significance level

Hi everyone,

I am studying a university level stats course at the moment and I have been given some excerises to take home that I am struggling with. I am asked to calculate sample size for a hypothesis that requires an 90% probability of detecting a difference at a significance threshold of 0.05. I need to use a probability to do this, but how?

Thank you,


Well-Known Member
You need more information than this. Does the exercise also mention SD, minimum detectable difference or effect size?