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Question 8#

Which of the following statements is INCORRECT when referring to a p-value?

A. Assesses the strength of evidence against the null hypothesis
B. Is the probability that the null hypothesis is true
C. A p-value less than 0.05 means that the 95% confidence interval does not contain the null value
D. The p-value does not indicate the size or importance of the observed effect
E. When interpreting the results of an analysis, the p-value should always be considered alongside the confidence interval

Correct Answer is B

Comment:

Answer B

A p-value is generated by performing a hypothesis (significance) test and provides a measure of how confident one can be in rejecting the null hypothesis. A commonly used cut-off for a statistically significant result is <0.05 and with a p-value below this, the null value will not be within the 95% confidence limits. At this level, there is less than a 5% probability that the observed effect could have resulted by chance if the null hypothesis were true. The confidence interval should always be interpreted alongside the p-value, as even with a very significant result (very low p-value), the confidence interval may indicate no important difference between groups.