I am interested in the prevalence of two conditions within the same population. I have the prevalence of the conditions for a number of years. According to the chi2 test for trend the prevalence for both conditions show a linear trend.
How do I compare the linear trends of the prevalences? Comparing the prevalence of the conditions without taking the log makes not much sense to me.
Is it like lm(log10(prevalence) ~ years*condition).
or do I have to take log10(years) as well.
What would you plot to visualise the trend
- plot(years,log10(prevalence))
- plot(log10(years),log10(prevalence))