What does a null hypothesis state?

A null hypothesis is a foundational concept in statistical hypothesis testing. It specifically states that there is no effect or no difference between groups being studied. In other words, it serves as a default position that indicates any observed differences are due to random chance rather than a true underlying difference or effect.

Choosing this answer reflects an understanding that the null hypothesis is essential in determining whether the data provides sufficient evidence to reject it in favor of an alternative hypothesis. The alternative hypothesis suggests that a significant effect or difference does exist.

This framework is crucial for studies as it provides a basis for statistical testing, allowing researchers to assess the strength of evidence against the null hypothesis. When researchers find enough evidence to reject the null hypothesis, they can infer that their findings may imply that an effect or difference is present.