False Negative

Definition

A false negative occurs when a test or diagnostic procedure fails to detect the presence of a condition or characteristic that is actually present. In the context of hypothesis testing, a false negative refers to the scenario where the null hypothesis is true, but the test statistic leads to the incorrect conclusion of failing to reject the null hypothesis.

5 Must Know Facts For Your Next Test

1. A false negative occurs when the test statistic fails to reject the null hypothesis, even though the null hypothesis is actually false.
2. False negatives are associated with a lack of statistical power, meaning the test does not have enough sensitivity to detect a significant effect when it is present.
3. Increasing the sample size, effect size, or significance level can help reduce the probability of a false negative.
4. False negatives can lead to missed opportunities for intervention or treatment, as well as incorrect conclusions about the relationship between variables.
5. Researchers must carefully consider the consequences of false negatives when designing and interpreting the results of their studies.

Review Questions

• Explain the relationship between a false negative and the null hypothesis.
  • A false negative occurs when the null hypothesis is true, but the test statistic fails to reject the null hypothesis. This means that the test has incorrectly concluded that there is no significant difference or relationship, when in fact, the null hypothesis is false. The probability of a false negative is directly related to the power of the statistical test, which is the likelihood of correctly rejecting the null hypothesis when it is false.
• Describe how the probability of a false negative can be reduced in a hypothesis testing scenario.
  • The probability of a false negative can be reduced by increasing the statistical power of the test. This can be achieved by increasing the sample size, effect size, or significance level. A larger sample size provides more information and can help detect smaller effects, while a higher effect size makes the difference between the null and alternative hypotheses more pronounced. Additionally, increasing the significance level (e.g., from α = 0.05 to α = 0.01) reduces the chances of a false negative, but also increases the risk of a false positive (Type I error).
• Analyze the potential consequences of a false negative in the context of hypothesis testing and decision-making.
  • A false negative can have serious consequences in decision-making, as it can lead to the incorrect conclusion that there is no significant difference or relationship when one actually exists. This can result in missed opportunities for intervention, treatment, or policy changes that could have had a positive impact. Additionally, false negatives can contribute to the publication bias in the scientific literature, where studies with non-significant findings are less likely to be published, skewing the overall understanding of a phenomenon. Researchers must carefully consider the potential consequences of false negatives when designing their studies and interpreting the results to ensure that important findings are not overlooked.

Related terms

Null Hypothesis: The null hypothesis is a statistical hypothesis that states that there is no significant difference between specified populations, or no relationship between variables.

Type II Error: A Type II error occurs when the null hypothesis is false, but the test fails to reject it, leading to the incorrect conclusion that there is no significant difference or relationship.

Power of a Test: The power of a test is the probability that the test will correctly reject the null hypothesis when it is false, which is equivalent to 1 minus the probability of a Type II error.