Reject

Definition

In the context of statistical hypothesis testing, to reject means to make the decision to not accept or support the null hypothesis based on the available evidence. This term is closely tied to the concepts of null and alternative hypotheses, as well as Type I and Type II errors.

5 Must Know Facts For Your Next Test

1. Rejecting the null hypothesis means that the researcher has sufficient evidence to conclude that the alternative hypothesis is true.
2. The decision to reject the null hypothesis is based on the p-value, which represents the probability of obtaining the observed or more extreme results if the null hypothesis is true.
3. If the p-value is less than the predetermined significance level (usually 0.05 or 5%), the researcher can reject the null hypothesis and conclude that the alternative hypothesis is supported by the data.
4. Rejecting the null hypothesis does not necessarily mean that the alternative hypothesis is true, as there is still a possibility of making a Type I error.
5. The power of a statistical test is the probability of rejecting the null hypothesis when it is false, which is important in determining the appropriate sample size and detecting meaningful effects.

Review Questions

• Explain the relationship between rejecting the null hypothesis and the alternative hypothesis.
  • Rejecting the null hypothesis means that the researcher has sufficient evidence to conclude that the alternative hypothesis is true. The null hypothesis represents a claim of no effect or no difference, while the alternative hypothesis represents a claim of an effect or a difference. By rejecting the null hypothesis, the researcher is essentially accepting the alternative hypothesis as the more plausible explanation for the observed data.
• Describe the role of the p-value in the decision to reject the null hypothesis.
  • The p-value is a key factor in determining whether to reject the null hypothesis. The p-value represents the probability of obtaining the observed or more extreme results if the null hypothesis is true. If the p-value is less than the predetermined significance level (typically 0.05 or 5%), the researcher can reject the null hypothesis and conclude that the alternative hypothesis is supported by the data. The smaller the p-value, the stronger the evidence against the null hypothesis and the more confident the researcher can be in rejecting it.
• Evaluate the potential consequences of rejecting the null hypothesis when it is actually true, and how this relates to the concept of a Type I error.
  • When the researcher rejects the null hypothesis when it is actually true, they have committed a Type I error. This means that they have concluded that there is an effect or a difference when in reality, there is none. The consequences of a Type I error can be serious, as it can lead to the implementation of ineffective or unnecessary interventions, the allocation of resources to non-existent problems, or the drawing of incorrect conclusions about the population or phenomenon being studied. Understanding the risk of a Type I error and minimizing it through appropriate statistical methods and significance levels is crucial in making informed decisions when rejecting the null hypothesis.

Related terms

Null Hypothesis: The null hypothesis, denoted as H0, is a statement that the researcher believes is true and wants to test. It typically represents no effect or no difference between groups.

Alternative Hypothesis: The alternative hypothesis, denoted as H1 or Ha, is a statement that the researcher believes is true if the null hypothesis is false. It typically represents an effect or a difference between groups.

Type I Error: A Type I error occurs when the null hypothesis is true, but the researcher rejects it, concluding that there is an effect or difference when there is none.