What is an alternative hypothesis (H1)?

The alternative hypothesis (H1) is a proposition that posits there is a difference, effect, or relationship in the population being studied. It is the hypothesis that researchers typically aim to support through their studies, suggesting that something significant is occurring beyond random chance.

When researchers formulate their hypotheses, they commonly establish the null hypothesis (H0), which asserts that there is no effect or no difference. The alternative hypothesis, therefore, stands in contrast to this null hypothesis, indicating that the experimental treatment or conditions have a measurable impact on the results. This is crucial in hypothesis testing, as researchers conduct statistical tests to determine whether there is sufficient evidence to reject the null hypothesis in favor of the alternative hypothesis.

In the context of the other options, the first choice outlines the null hypothesis rather than the alternative. The third choice erroneously suggests that the hypothesis cannot be tested, which misunderstands the nature of both null and alternative hypotheses, as both can and should be evaluated based on empirical data. Lastly, the fourth option describes a statistical concept related to variability in data rather than providing a definition of what constitutes an alternative hypothesis in hypothesis testing.