Need to set a specific prior based on base rate information?
I am trying to find the probability of certain symptoms based on group membership (healthy controls vs. people with a particular disease). I used a default Cauchy prior of 0.707.
It then occurred to me that perhaps I need to use base rate information of the disease.
However, I am not sure if this would be appropriate, and if so, how I would input this information into JASP. There might be separate base rate information for a particular symptom or of the disease itself (prevalence?) - which should I use? And how do I translate this into a prior? If no base rate information is present, do I just use the default?
I'm not sure if I'm conceptualizing this correctly or if the default prior I used initially is alright. I'd appreciate any help. Thanks.