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