Tag Archives: p values

P values and hypothesis tests cannot indicate the size or precision of effects

P values and hypothesis testing methods are frequently misused in clinical and experimental research, perhaps because of the misconception that they provide simple, objective tools to separate true from untrue facts. In a new paper, the cardiologist Daniel Mark and statisticians Kerry Lee and Frank Harrell explain the role and limitations of p values and hypothesis tests in clinical research.

Read more

How to calculate the confidence interval from a p value

Confidence intervals are widely reported in published research and are usually thought to provide more information than p values from significance tests because confidence intervals indicate how precise an estimate is. Sometimes, however, investigators report an estimate (eg. a mean) and p value, but not the confidence interval about the estimate. In a BMJ statistics note, statisticians Doug Altman and

Read more

Common misinterpretations of statistical tests

Researchers often use statistical tests to test hypotheses and/or infer properties of a population based on properties of a sample. A key idea is that all statistical tests assume a statistical model provides a complete and valid representation of variability in the data, and faithfully reflects how the study was conducted and the phenomena being tested. For example, when we

Read more

The limitations of p values

A recent Nature commentary highlighted a statement by the American Statistical Association on principles to guide the use of p values for interpretation of research findings. The statement was issued out of concern for the lack of understanding of p values and what they imply. Specifically, the 6 principles of the statement are: P values can indicate how incompatible the

Read more