# Including % Race/Ethnicity in Regression Model

I have been examining high school graduation rates, and wanted to include race/ethnicity as a control. The only data available is % of students identifying as one of 7 race/ethnicity categories. My concern is that these percentages are inherently dependent upon each other.

Is it appropriate to include each of those percentages as independent variables in the regression? If not, is there a method for handling such dependent variables?

• Your unit of analysis is high school? If I understand things correctly, each high school would give rise to 7 race/ethnicity percentages and the 7 percentages would add up to 100%. So you can't add all 7 percentages as control variables in your model, as you would have perfect multicollinearity between them. You could add just 6 of them perhaps and leave one out of the model entirely. – Isabella Ghement Mar 4 at 16:38
• The other thing you could do is to identify a subset of race/ethnicity categories you are most interested in (e.g., white and hispanic ) and define a percentage that reflects that subset (e.g., 60% white + 20% hispanic = 80% white or hispanic). Then you can include that percentage in the model. Or you could use a mixture of percentages: 60% white and 10% black or hispanic (as long as they don't add up to 100%). – Isabella Ghement Mar 4 at 16:40
• @IsabellaGhement that's a good answer, and I'd encourage you to post it as one. – Weiwen Ng Mar 4 at 17:16
• Thank you, @WeiwenNg! I posted the comments as an answer. – Isabella Ghement Mar 4 at 18:22