# Derive a normal prior for the log hazard ratio parameter based on a guess at the hazard ratio

Source:`R/priors.R`

`p_hr.Rd`

Derive a normal prior for the log hazard ratio parameter based on a guess at the hazard ratio. This assumes that the log upper limit is 2 standard deviations away from the log median.

## Arguments

- median
Best guess (prior median) for a typical hazard ratio

- upper
Upper limit of 95% credible interval for hazard ratio

## Value

A normal prior in the format returned by `p_normal`

, which can
be passed directly to the `prior_loghr`

argument in `survextrap`

.