How is a "null hypothesis" defined?

A "null hypothesis" is defined as a statement claiming no effect or difference between groups. This concept is fundamental in statistical hypothesis testing, where researchers seek to establish whether there is enough evidence to reject this hypothesis in favor of an alternative hypothesis, which suggests that there is some effect or difference.

In the context of experimental research, the null hypothesis serves as a baseline that indicates no relationship between the independent and dependent variables. For instance, if researchers are examining whether a new therapy is more effective than a standard treatment, the null hypothesis would posit that there is no difference in effectiveness between the two therapies.

This formulation allows for clear statistical testing; if data collected from an experiment shows sufficient evidence against the null hypothesis, researchers may reject it, leading to acceptance of an alternative hypothesis indicating a statistically significant effect or difference. The null hypothesis is not about being proven true; instead, it's about providing a benchmark for comparison.