model - How do I do an interaction term with the same variable in R

Question

I am trying to interact the same variable (baseharm) in my regression but I am not seeing the result of the interaction, just the variable's coefficient on its own. Is this possible to do? And if so, how?:

harm13 <- lm(notify ~ newviolent1 + as.factor(distress_all) + baseharm + (baseharm*baseharm) + offrole1 + injuryharm + weapharm + harmhatescore, fixed_effects = ~ YEAR, data = subset(larceny, distress_all <= 3)) harm13

Answer 1

等待大神答复