Kaplan–Meier
Non-parametric survival curve from duration and an event indicator, with an optional two-group log-rank test.
When to use it
Use Kaplan–Meier when each row is a person (or unit) with a time until an event, and some people are still event-free when observation stops. “Do patients on the new arm stay event-free longer than standard care?” is the usual two-group question. A covariate that should shift the hazard is Cox. The cumulative hazard of the same times is Nelson–Aalen.
Assumptions
Duration must be positive and numeric. Rows with missing or non-positive duration are dropped. The event column is 1 for the event and 0 for censored; the service also reads true, yes, y, and event as 1. At least three valid rows are required.
The log-rank p-value is only computed when a grouping column has exactly two levels. Three or more groups still get a curve each (up to four groups), with no overall log-rank. There is no proportional-hazards check on this page.
The chart is a step curve with marks at censored times. It does not draw confidence bands.
Running it in Tensr
Options
Prop
Type
Reading the output
Eighty people, 40 on standard care and 40 on a new arm. Time is weeks until the event. The new arm was built with a slightly lower hazard, and about a third of the rows are censored. The log-rank is the two-group comparison.
Kaplan–Meier survival analysis using weeks and event. The primary result is not significant (p = .545). This is not large enough to treat the comparison this page is about as a reliable association. The result is non-significant: the data are still compatible with no effect. Metrics: Observations = 80; Events = 58; Log-rank p-value = .545.
Reporting (APA 7)
Kaplan–Meier survival analysis using weeks and event. This result is not significant (p = .545). Report the estimate with that p, and do not describe the pattern as a reliable effect.
Coming from SPSS
SPSS is Analyze → Survival → Kaplan-Meier. Tensr’s Analyze menu has the same Survival section. The path string stored for this item is Analyze → Survival → Kaplan-Meier.
SPSS prints a survival table (time, n at risk, n events, survival). Tensr’s report is the observation and event counts, the log-rank p when there are two groups, and the step chart. It does not print a life table.
Related
A numeric covariate on the same times is Cox proportional hazards. The cumulative hazard is Nelson–Aalen.