The log-rank test is a statistical test used to compare two or more groups of subjects with respect to the corresponding durations of time to the occurrence of a specific event. The log-rank test is frequently used in medical research to compare the survival times between patients with the same condition or disease who can be grouped by treatment, age, sex, or some other factors such as specific disease characteristics. Similar to other statistical tests, the log-rank test result is reported as a p value between 0 and 1. A smaller p value indicates stronger evidence for the differences between the tested groups. A commonly used convention is to interpret a p value of .05 or less as evidence of statistically significant differences.