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Thread: control of type I error?

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    control of type I error?




    Hello forum,

    I am seeking your advise. Here is the problem:

    In a clinical trial, we will collect MRI imaging data from each patient participating in the study. The imaging data will be read by 3 independent image readers. So we have 3 sets of evaluations from the 3 readers. Then we run a statstical test based on each data set. Now the protocol states that if at least 2 out of the 3 tests are significant, then we can claim the study to be positive.

    To calcuate the sample size needed, do you think we need to control the type I error rate in this situation?

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    Re: control of type I error?

    What test are you using? Please provide some more detail.

    Do you have a gold standard to confirm the positive?
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    Re: control of type I error?

    It is a non-inferiority test comparing with placebo. So we will have 3 p-values from the 3 readers evalutions. If we had just one reader, then the trial is positive is the p-value is less than 0.05. The question is for the current proposal (i.e. at least 2 out of the 3 p-values is less than 0.05, then we claim the trial as positive), is there an issue with inflating the type I error rate?

    Quote Originally Posted by hlsmith View Post
    What test are you using? Please provide some more detail.

    Do you have a gold standard to confirm the positive?

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    Re: control of type I error?


    Not completely my forte, but I get what you thinking. This would be similar to multiple comparisons. What do the people in your field do? Can you find anyone else using this approach in the literature?
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