I plan to do a conjoint survey experiment in which I randomly change attributes of hypothetical job candidates and show two types of potential candidates with different attributes. Then, I ask respondents to select which candidate they prefer to hire. My aim is to analyze what attribute(s) affects the likelihood for being hired.
Let's say I am mainly interested in four attributes of candidates, 1. gender (male, female), 2. age (30, 40, 50, 55), 3. working experience in the same sector (no, yes). I understand that I should randomly assign these different attributes with different levels to respondents in conjoint experiment.
However, I wonder what I should do with other less important attributes for my research such as education level (BA, MA, Ph.D.), exam score (low, middle, high) in conjoint survey question. Should I also randomly assign these attributes to respondents? Or should I just show a fixed attribute (eg. BA, middle level exam score) as one of the attributes together with the above attributes? Or should I just explain that we assume that all job candidates have BA, middle level exam score, no political connection in survey instruction?