Friday, April 17, 2015

Biostatistics Faculty and NIH Awards at U.S. Medical Schools.

The number of biostatistics faculty is positively associated with the amount of NIH research awards in medical schools in the U.S.  (Am Stat. 2015 Feb;69(1):34-40.)

Monday, February 16, 2015

Plastic Surgery Residents' Understanding and Attitudes Toward Biostatistics: A National Survey.

This study found that plastic surgery residents felt that knowledge of biostatistics was important, however upon objective testing they only had a fair understanding of statistical principles. The residents had difficulty with study study design, ANOVA, regression, and identification of a statistically significant result. Confidence was not a good predictor of objective performance.  (Ann Plast Surg. 2015 Jan 30.)

Tuesday, February 10, 2015

Bonferroni multiple comparison test

When performing multiple tests of significance upon a single dataset, there is an ever increasing chance that at least one of these tests will be statistically significant. For example, a p-value of 0.05 means there is a 1-in-20 likelihood of the statistical result occurring by chance alone.  If we perform 20 such tests, then there is a 1-in-1 likelihood of at least one result having a p-value of 0.05 or less.

The Bonferroni correction is simple. When multiple tests of significance are performed, then the cutoff p-value for statistical significance is set to equal 0.05 divided by the number of tests performed.

For example, if 10 tests of significance are performed, the cutoff p-value for statistical significance would be 0.05 / 10 = 0.005 when using the Bonferroni correction. If 5 tests are performed, then the cutoff p-value would be 0.05 / 5 = 0.01.