Skip to main content icon/video/no-internet

A false negative, also known as Type II or beta error, is an error that occurs when a researcher falsely concludes that there is no effect. Therefore, this is also sometimes referred to as falsely failing to reject the null hypothesis (or simply “falsely failing to reject the null”). It is important to understand the concept of a false negative when conducting communication research so that scholars do not erroneously claim that an effect does not exist and so that scholars do not miss important findings. For example, assume that the true state of the world (reality) is that women have higher emotional intelligence scores than do men. A researcher collects data from a sample of men and women and finds that for this sample, men and women have similar emotional intelligence scores. On the basis of these data, the researcher concludes that there is no difference between men and women on emotional intelligence. Provided that in reality, there is a difference between men and women on emotional intelligence, the researcher has committed an error. This error is a false negative (or a Type II or beta error) because the researcher failed to detect an effect that actually exists. This entry examines the relationship between a false negative and statistical power, discusses the various ways that Type II error can be minimized, and concludes with an example relevant to communication research.

Type II Error and Statistical Power

Type II error is directly related to statistical power, which is the ability of a test to detect an effect if one really exists. The more statistical power there is, the less likely one is to miss an effect (false negative). The exact relationship is expressed as power = 1 − beta. In other words, the odds of finding an effect if one exists (power), plus the odds of missing an effect if one exists (false negative), equals 100%. For example, if the power for a given test is 80%, this means that if a real effect exists in the population, 80% of the time, a researcher will be able to detect it in the sample. Because power = 1 − beta, this means that 20% of the time, the effect will fail to be detected. Therefore, the likelihood of committing a Type II error (false negative) is 20%, if there is an effect to be found.

A false negative can exist only if the true state of the world is that there is an effect. This means that if an effect does not exist, a Type II error cannot be committed. Therefore, the beta (or Type II error rate) is the odds of failing to find a real effect, not the odds of failing to find an effect. This is an important distinction. If one fails to find an effect, there is a chance that this is not an error because it is possible that there was no effect to find.

Minimizing Type II Error

Depending on the nature of a research project, scholars may be very concerned with the idea of failing to find an effect. Therefore, they will likely work to increase their power so that they decrease their Type II error rate. One way to increase power and decrease the Type II error rate is to increase sample size. The larger the sample, the more power there is, and the less likely the researcher is to miss an effect if there is one to be found (false negative). Power can also be increased by manipulating the alpha error rate, using proper measures, and other methodological strategies.

...

  • Loading...
locked icon

Sign in to access this content

Get a 30 day FREE TRIAL

  • Watch videos from a variety of sources bringing classroom topics to life
  • Read modern, diverse business cases
  • Explore hundreds of books and reference titles

Sage Recommends

We found other relevant content for you on other Sage platforms.

Loading