Hi! I am performing cox regressions with a categorical indep. variable. In the survey, we have a likert-scale with 7 responses from "never" "once" ... to "daily". We coded 1) never 2) once 3) reoccurring. I want to know if (3) reoccurring exposure has a stronger association with the outcome than exposure (2) "once". My supervisor suggested treating the indep. variable as continuous (put it in stata without the i.) and claims that getting a stat. sign. p-value would prove that there is a trend. I find this hard to believe, it has been questioned by a reviewer and I can't find this described anywhere. I suggested instead to compare the two coefficients with a Wald test for stat. sign. of "not being the same". I would be greatefull for a) an explanation that supports my supervisors suggestion (possibly literature I can reference) b) support for the Wald test or c) an alternative to test this. Just to say it in advance: Including the variable with finer categories is off the table due to low power.