Erratum to: Statistics review 3: Hypothesis testing and Pvalues

An erratum to Statistics review 3: Hypothesis testing and Pvalues, by Elise Whitley and Jonathan Ball.

In the original version of this article [1], the words 'if the null hypothesis is true' were omitted from the first sentence of the first key message. The key message should have read as follows:

'A P value is the probability that an observed effect is simply due to chance, if the Null hypothesis is true; it therefore provides a measure of the strength of an association. A P value does not provide any measure of the size of an effect, and cannot be used in isolation to inform clinical judgement.'