Sample size

[Hilda Oropeza Cruz]

Hi everyone,

Any of you have suggestions on how to calculate a sample size for a finite population? I want to carry out an observational study and I just want to look at the prevalence of disease. I have a defined population (4056 subjects) and I want to know how much participants do I need to have a representative sample...

I'd appreciate your suggestions,

Thanks

[daniel klein]

To the best of my knowledge, the term "representative" does not have an agreed-on definition. To me, that term just means a random sample, drawn in a way in which an underlying statistical theory tells me whether and how results obtained from that sample can be projected to the population. A sample size of N=1 randomly selected unit satisfies this definition.

Instead of asking for a representative sample, you need to decide how precise you want your estimate to be. power answers this question for simple random samples. See

help power

Best
Daniel