The education (EDUC) variable in the General Social Survey is the number of years of education. In the Survey of Consumer Finances, the education (EDUC) variable is defined as follows:

EDUC: –1 = Less than first grade, 1 = 1–4 grades, 2 = 5 or 6 grades, 3 = 7 or 8 grades, 4 = 9th grade, 5 = 10th grade, 6 = 11th grade, 7 = 12th grade but no diploma, 8 = High school graduate or equivalent, 9 = Some college but no degree, 10 = Associate degree or occupation/vocation program, 11 = Associate degree-academic program, 12 = Bachelor’s degree, 13 = Master’s degree, 14 = Doctorate or professional school degree. 

Is this variable interval (as in the General Social Survey) or ordinal? Explain.