ECO problem

dat <- read.csv("D:/Data/Exercise 10 RDD.csv") dat # c = 5, x = assignment variable, y = outcome # Part (a) T <- ifelse(dat$x >= 5,1,0) T xstar <- dat$x - 5 xstar xstarT <- xstar*T xstarT # Part (b) reg1 <- lm(y ~ T + xstar, data=dat) summary(reg1) # Part (c) reg2 <- lm(y ~ T + xstar + xstarT, data=dat) summary(reg2) # Plot (d) # Plot with common slope plot(y ~ xstar, data=dat) abline(a=26.66, b=7.35,col="orange") abline(a=61.55, b=7.35,col="purple") # Plot (e) # Plot with unequal slopes plot(y ~ xstar, data=dat) abline(a=24.7, b=3.75,col="blue") abline(a=60.1,b=9.9,col="green") # Part (f) anova(reg1,reg2) # Part (g) # Tighten the window around the cutoff of 5, say # (4.5, 5.5) and rerun the two slope model. dat.df <- data.frame(dat) dat.df T.df <- data.frame(T) T.df xstar.df <- data.frame(xstar) xstar.df xstarT.df <- data.frame(xstarT) xstarT.df dat2.df <- cbind(dat.df,T.df,xstar.df,xstarT.df) dat2.df dat3.df <- subset(dat2.df,xstar <= 0.5 & xstar >= -0.5) dat3.df # Part (h) reg3 <- lm(y ~ T + xstar + xstarT, data=dat3.df) summary(reg3) # Part (i) reg4 <- lm(y ~ T + xstar, data=dat3.df) summary(reg4) # Part (j) anova(reg3,reg4)