Sample Size Help

#1
Hello:
Its been about 9 years since I took my Statistics course, and am hoping you kind souls can provide some guidance.

I am evaluating the results of 2 groups of surveys - one group where there was intervention pre-survey and one where there was no intervention (control group).

At this point, I'm not sure if I have "enough" samples in my intervention group to determine reliability at a 95% confidence interval. In fact, I'm not sure even how to evalute this. I am concerned someone will say "You don't have enough samples in your intervention group to validate your claim that intervention works".

I have the n, mean and standard deviations for both control groups, and the aggregate.

How should I proceed?

Any assistance is much appreciated, and please remember I am a beginner.

Many thanks in advance-
Ebachenh:)
 

JohnM

TS Contributor
#2
Ebachenh,

Give us some more background on your survey (how many samples you have from each group, exactly what you're measuring, some basic stats - averages, std deviations, etc., what the hypothesis is...)

We should be able to help if you can give us as much info as possible. We can tell you if you have a large enough sample to tell if the intervention vs. no-intervention differences are significant.

John