Which method is commonly used to compare survival curves between groups?

• A. Log-rank test.
• B. ANOVA.
• C. Pearson correlation.
• D. Chi-square test for independence.

Answer: (A)

Comparing survival curves from time-to-event data with censoring is a common task, and the log-rank test is the go-to method for this. It examines whether the observed number of events at each event time in each group differs from what would be expected if the groups truly had the same survival experience. By aggregating these differences over all event times, it provides a chi-square statistic to assess whether there’s a real difference in survival curves, while properly handling censored observations. This approach is specifically designed for survival data and does not rely on normality or simple mean comparisons.

Why the other options aren’t suitable here: ANOVA compares means of a continuous outcome and doesn’t handle censoring or the time-to-event structure. Pearson correlation looks at linear association between two variables and isn’t about comparing survival experiences over time. A chi-square test for independence assesses relationships between categorical variables in a cross-tabulation and ignores the timing of events and censoring inherent in survival data.