Hi all,

We are performing a follow-up study of a medical test, investigating if it's useful for predicting mortality. I've spent quite a few hours trying to estimate the sample size needed to perform a valid study but I'm still very unsure how to go about this, and I believe I'm at the top of confusion right now... I therefore seek your help!

Several values are known from a previous, smaller study, but currently I'm so confused that I'm unsure which ones are actually needed for this calculation. I've tried several different approaches but have a hard time figuring out what actually makes sense in this setting.

Can anyone shed a bit of light on this and hopefully send us in the right direction?

Best wishes,

Rune Jensen

We are performing a follow-up study of a medical test, investigating if it's useful for predicting mortality. I've spent quite a few hours trying to estimate the sample size needed to perform a valid study but I'm still very unsure how to go about this, and I believe I'm at the top of confusion right now... I therefore seek your help!

**The problem:**Supposedly a medical test can be used to split patients into two groups; low risk and high risk of dying. We wish to test this hypothesis through a prospective study where the test is performed and patients followed up after a given time interval. For this study we wish to estimate the sample size needed to obtain a valid result.Several values are known from a previous, smaller study, but currently I'm so confused that I'm unsure which ones are actually needed for this calculation. I've tried several different approaches but have a hard time figuring out what actually makes sense in this setting.

Can anyone shed a bit of light on this and hopefully send us in the right direction?

Best wishes,

Rune Jensen

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