I am currently working with survey data, collected across different locations, but with slightly different units of measurement.
For example, on questions such as "What is your level of education", some participants had the choice between only 3 categories, others 5 categories etc. The categories are always ordered in the same direction (less to more education) but their number vary.
The categories are:
in some locations, High School, Bachelor's degree, Master’s/PhD
in other locations, No high school degree, high school, some university education, bachelor's degree, Master's/PhD
I would like to include this variable in a regression. I am wondering if standardizing the variables (using z-scores) will help? I know it can help compare scores when measurement varies, but here I am worried that the categorical nature of the data makes this solution unreliable.
I know that this will "erase" differences between the different locations, but I am mostly interested in comparing how being in the lower part of the distribution vs. higher part affects the dependent variable.