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113 Math

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113.020.020.50 Survival Analysis - Proportional Hazards PH

# Prorporational Hazards (PH)

Proportional hazards are a class of 113.020.020 Statistics - Survival Analysis in statistics (1). They predict the amount of time before some event occurs, like a patient dying or a customer churning.

113.020.020.50.10 Proportional Hazards - Mathematical desc of Cox PH

## From my Lucky8 notes

- has a hard time fitting to yearly data
- needs a good history of data
- needs a big enough number of new customer adds (small numbers are hard)
- hard when you have a direct sales force model

### Used to predict saturation

This and other diffusion models are used to predict saturation.

### There are other growth models out there

We used PH a lot at Lucky8, but we occasionally used other growth models as well.

- 113.020.010.10.20 Regression models - Exponential Distribution

- Proportional Hazards vs. Weibull: https://core.ac.uk/download/pdf/5172563.pdf

References:

- 1: https://en.wikipedia.org/wiki/Proportional_hazards_model

- 20200706 Lucky8 notes (clustered)

##### Source:

- Me