# Statistical considerations for a study of the effect of one variable on another

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Note: The power calculation uses the non-central t function, pt(x,df,ncen), and it's inverse qt*

Power=pt(qt(.025,n-1,0),n-1,-(delta/sigma)*sqrt(n)), power is truncated rather than rounded.

If power is specified the other parameters are found by searching.

## Response (for previous request)

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This software developed by David Schoenfeld, Ph.D. (dschoenfeld@partners.org), with support from the MGH Mallinckrodt General Clinical Research Center. Javascript version developed by REMorse.

These calculations are based on assumptions which may not be true for the clinical trial that you are planning. We do not guarantee the accuracy of these calculations or their suitability for your application. We suggest that you speak to a biostatistical consultant when planning a clinical trial. Please contact us if you have any questions or problems using this software