Is it ok to have more cases than the control samples in a case-control study? Suppose, I have 150 cancer samples against 108 control samples then will it be enough to conduct the study with the current sample size or do I have to add more controls for the study?
Normally the sample size is derive prior to the study not afterwards. It is based on the desired power and an effect-size you find minimally meaningful. Posterior looking at the sample size and deciding it is not sufficient is called data peaking or optional stopping it violates the principle of independence and invalidates your result. So yes, your study is large enough and if your sample size was insufficient to 'detect' something repeat the study with a larger sample size.
It depends on different factors. Try to approximate the sample sizes and keep in mind the proportional aspect of age, gender, etc...
Dear Sarah,
Yes, it’s okay to have more cases than controls in a case-control study, as it can still provide reliable results, though having a roughly equal sample size often improves statistical power. If controls are limited, consider ensuring they’re well-matched for accuracy (Schulz & Grimes, 2002; Wacholder et al., 1992).
Best regards,
Anitha,
Research Scholar,
Ramaiah University of Applied sciences,Bengaluru, India
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