What risk is increased when the sample size is too small in experimental research?

When the sample size in experimental research is too small, the risk of increased Type II errors is heightened. A Type II error occurs when a researcher fails to reject a false null hypothesis, meaning they miss detecting an effect or relationship that actually exists. Small sample sizes can lead to insufficient statistical power, which makes it harder to detect true effects when they are present. This can happen because smaller samples provide less precise estimates of population parameters and can lead to greater variability in results.

In essence, with a small sample size, the statistical tests applied might not have enough power to identify differences or effects that may be present, causing researchers to erroneously conclude that there is no effect when, in fact, there is one. This is a significant concern in experimental research, where detecting true differences is often the primary goal. Therefore, maintaining an adequately large sample size is crucial to enhance the reliability of the findings and minimize the risk of Type II errors.