What is the effect of a low p-value in hypothesis testing?

A low p-value in hypothesis testing indicates strong evidence against the null hypothesis. This means that the observed data is unlikely to occur under the assumption that the null hypothesis is true. The p-value quantifies the strength of the evidence against the null hypothesis, with lower values suggesting that the data provide more substantial proof for rejecting it. In practice, when the p-value falls below a predetermined significance level (often 0.05), researchers typically reject the null hypothesis, indicating that the results of the study are statistically significant.

This relationship between the p-value and the null hypothesis forms the foundation of hypothesis testing. The role of a p-value is to help determine whether the evidence is strong enough to warrant skepticism about the null hypothesis, which posits that there is no effect or no difference in the context of the study.

In contrast, higher p-values would fail to show significant evidence against the null hypothesis, potentially leading researchers to retain it. Moreover, a p-value does not determine the truth of the hypothesis itself but rather the evidence provided by the data in relation to that hypothesis. Therefore, understanding the implications of a low p-value is crucial in making informed decisions based on statistical analyses.