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113 Math

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113.020.020.20 Survival analysis - Basic math

# Survival Analysis - Basic Math

Survival function = Probability of surviving beyond time t

$$S(t) = P(T > t)$$

Hazard (HAZ) = probability of dying in next few seconds given that you're alive now

$$P(T < (t + \delta) | T > t)$$

Hazard Ratio (HR) =

$$\frac{HAZ, x=1}{HAX, x=0}$$

- If `HR = 2`

that means that somebody who is exposed has double the risk of dying than somebody who is not exposed.

- Rate of decrease of the Hazard

##### Source:

- Me