I am trying to run a one-factor model of two regressors. One is a category (group: other, Africa, oecd, etc.) and the other one is expected living time(lifeExpF). When I run the command:
m1 = lm(lifeExpF~group,data = UN11)
It only gives me:
Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 82.446 1.128 73.095 < 2e-16 *** groupother -7.120 1.271 -5.602 7.1e-08 *** groupafrica -22.674 1.420 -15.968 < 2e-16 *** ---
I am not sure why it gives me only two levels: groupother, groupafrica. In my factor "group", there are 3 levels: other, africa and oecd.
Do you know why the summary does not give me "groupoecd"?