I had a question regarding my final project for school. I am currently in the process of getting my Master's Degree in Public Health, with a focus on Biostatistics. I am doing a study from a dataset that my instructor created for us, which consists of a variety of information on patients, such as age, demographics, whether or not they are diabetic, etc. I decided to study the effects of income on dengue infection. I wanted to know how I can control for variables that might confound the study, including patients who are diabetic or HIV-positive? I figured these might confound the study since antibody testing is required for dengue diagnosis, and those that are immunocompromised might have alternating levels of anti-dengue antibodies (IgG).