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  "body": "\n## Summary\n\nThe Kaplan–Meier estimator is a nonparametric estimator of the [[survival function|QTM1HZM53Q]] from right-[[censored|MY8ZZP84NP]] data.\nIt multiplies, over the observed event times, the fractions of subjects at risk who survive each event time.\nWithout censoring it reduces to one minus the [[empirical distribution function|A05WR6TEK5]].\nIt was introduced by Edward Kaplan and Paul Meier, and its step-shaped plot is the most common figure in medical survival studies.\n\n## Explanations\n\n### L1 human\n\nFollow four patients: deaths at months $2$, $5$ and $7$, and one patient who leaves the study at month $3$.\nAt month $2$ one of four patients at risk dies, so survival drops to $3/4$.\nThe patient who leaves at month $3$ is simply removed from the group at risk, without counting a death.\nAt month $5$ one of the two remaining patients dies, so survival drops to $3/4 \\cdot 1/2 = 3/8$.\nThe censored patient helped in the first step, and it does not distort the later ones.\n",
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