A p-value of 0.05 indicates the probability that results occurred by chance is what?

A p-value of 0.05 indicates that there is a 5% probability that the observed results could have occurred by chance under the null hypothesis. In statistical terms, this means that if the null hypothesis were true, you would expect to see results as extreme as those observed in 5 out of 100 experiments purely by random variation alone.

Understanding p-values is crucial in hypothesis testing as they help determine the significance of research findings. A p-value of 0.05 is often used as a threshold for statistical significance in many fields, indicating that the results are unlikely to be due to chance. This level of significance implies a 5% chance of incorrectly rejecting the null hypothesis when it is actually true, commonly referred to as a Type I error.

The other options misinterpret the magnitude of the p-value. For example, a p-value represented as a percentage less than 5% would indicate a smaller probability of results occurring by chance than what is conveyed by a p-value of 0.05. Recognizing that a p-value of 0.05 corresponds to a 5% chance helps clarify its importance in evaluating research data.