How do I adjust sample size for dropouts in my study?

How do I adjust sample size for dropouts in my study?

To adjust for dropouts, you can use a formula that accounts for the expected dropout rate. What is your current sample size?

My current sample size is 200, and I expect a dropout rate of 20%.

With a 20% dropout rate, you should increase your sample size by 25%. So, you would need about 250 participants.

Is there a specific formula I should use for this calculation?

Yes, the formula is: Adjusted Sample Size = Original Sample Size / (1 - Dropout Rate). For your case: 200 / (1 - 0.20) = 250.

Thanks! That makes it clearer. What if my dropout rate changes?

If your dropout rate changes, you can simply recalculate using the same formula with the new rate.