# XWUIChartKaplanMeier

A Kaplan-Meier survival chart backed by `XWUIChart` that steps a survival probability down over time, the standard view for survival/retention analysis where each drop marks an event. Provide named `series` of `{ x, y }` points (one curve per cohort) and pick a `block` (1-4) variant plus a `size` preset; legend and grid auto-toggle per block unless overridden.

## Basic Usage

Two named cohort series - `Series A` (30→64) and `Series B` (22→52) across Jan-Jun - drawn as survival curves.

```example
file: examples/BasicUsage.ts
html: examples/BasicUsage.html
title: Basic Usage
description: Two monthly cohort series drawn as a Kaplan-Meier chart at the md preset.
```

## SaaS Subscriber Retention

Two onboarding cohorts compared as Kaplan-Meier retention curves over twelve months.

```example
file: examples/SaasRetention.ts
html: examples/SaasRetention.html
title: SaaS Subscriber Retention
description: Q1 vs Q2 onboarding cohorts tracked as monthly retention curves at the lg preset.
```

## Treatment vs Control Survival

Clinical-trial style survival curves comparing a treatment arm against control across 24 weeks.

```example
file: examples/TreatmentSurvival.ts
html: examples/TreatmentSurvival.html
title: Treatment vs Control Survival
description: Progression-free survival of a treatment arm versus control over 24 weeks.
```

```api
```