i****o
发帖数: 242 | 1 3. A researcher is planning an intervention study to reduce childhood
obesity. The study will consist of a treatment group and placebo control.
The expected effect of the intervention will d=.50.
a. How many subjects will be required to detect a significant effect at
alpha=.05 with power=.80?
b. (Hard!) Now, assume that the investigator wants to improve power. She
knows that gender has a strong association with weight (r=.447). So, she
includes gender as a covariate in the analysis, mak | s*******9
发帖数: 35 | 2 My thought is that the sample size is the same as what you get from question
a. Gender is randomized to each condition in the case-control study; so you
do not need to worry about gender as a confounder because it is
automatically controlled by the study design (if gender is an interaction
factor, it will be a different story).
This is just my thought and I am not sure if it is correct or not. |
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