The Cytel blog keeps you up to speed with the latest developments in biostatistics and clinical biometrics.

How to handle conservativeness of Exact p-value?

September 18, 2017


By Ashwini Joshi

For small sample data or rare events data, exact non-parametric tests perform better than asymptotic tests. But they come with the disadvantage of conservativeness. Many corrections have been suggested to reduce this conservativeness but none of them solve the problems entirely.  StatXact provides various methods of computing exact p-values. Depending upon the problem at hand, the user can decide which one to use.
Let’s consider a hypothetical example of stratified count data. The example shows two sample data with two strata. Events in Treatment1 are rare as compared to the ones in Treatment0. But the event rates are comparable.

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How can the CMO/Biostatistician connection improve clinical development?

June 7, 2016

 At the recent CMO Summit East  James ( Jim) Bolognese, Cytel’s Senior Director of Strategic Consulting, and Lou Vaickus,MD, FACP, Founder and President of aktaPD jointly explored how the critical connection between a CMO and a biostatistician can help enhance communication with internal and external stakeholders, ensure patient safety and ultimately improve clinical development efficiency.  Below you can catch up with some of the key topics they covered and watch the video of the presentation. 


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What's the Value of P?

March 23, 2016

“How many statisticians does it take to ensure at least a 50% chance of a disagreement about p-values?” 

So questions George Cobb of Mt. Holyoke College in  his commentary on  the ASA’s 7th March ‘Statement  on P Values: context, process and purpose’

The association took the unprecedented step of publishing the statement following a long litany of criticism of misuse of the P value. This included the decision last year by Journal of Basic and Applied Social Pyschology to restrict the publication of papers where hypothesis testing is used for analysis.

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