I've collected some survey data on homeless individuals, surveying their drug use, education level, age, gender etc. I hope to run a logistic regression to see how impactful homelessness (+other dependent variables) are on the likelihood a child uses drugs.
DrugUser= B0 + B1Homeless + B3X3 + ... + u
However, due to the constraints of the study I was not able to survey randomly, only surveying those individuals who came into a homeless shelter (A convenience sample?). Hence the majority of the sample were made up of homeless people. Does this mean that any results I get for B1 would be spurious, as almost all of the sample is of homeless children and not a randomised sample of the population?
Therefore, is there anyway I can measure the effect of homelessness on drug use considering the quality of the data?
If not, could I still accurately measure the effects of the other variables on the likelihood an individual takes drugs that are not made bias by this convenience sample (like age, gender etc.)?
Is there any way I can use survey data like this to run a logistic regression at all?