Sample size

[Tom Salvitti]

Hi to everybody,
I need to calculate the sample size. The literature data is that the positive predictive value is 33.3%. How many subjects do I need to consider to have a study power of 80% and an alpha of 0.05. the command i think is power one proportion but how ?? thank you in advance

[Tom Salvitti]

According to you is it correct the instruction below??

power oneproportion 0.3, diff(0.2) oneside

[Tom Salvitti]

Thanks to everybody for the help