National Board Dental Hygiene Examination (NBDHE) Dental Hygienist Practice Test

What does the p-value in statistics typically represent?

1. Statistical significance

2. Variability in sample groups

3. How many subjects are needed

4. Different means

The correct answer is: Statistical significance

The p-value in statistics represents the probability that the observed data would occur under the null hypothesis, which posits that there is no effect or difference. A low p-value indicates strong evidence against the null hypothesis, suggesting that the observed effect is statistically significant. This means that researchers can reasonably reject the null hypothesis in favor of an alternative hypothesis, indicating that there is a notable difference or effect observed in the data. In practice, a common threshold for determining statistical significance is a p-value of less than 0.05; this suggests that there is less than a 5% probability that the observed results happened by chance under the null hypothesis. Thus, the p-value serves as a critical measure for interpreting the findings in statistical tests and determining whether the results of a study are meaningful in a scientific context. The other choices, while important concepts in statistics, do not encapsulate the specific role of the p-value. Variability in sample groups relates to how much the data points differ from each other, the determination of how many subjects are needed pertains to sample size calculations, and different means refer to the arithmetic averages of different groups, none of which directly define the significance of the p-value.