Welcome to the Institute for Digital Reseach and Education

plot(math, write)

plot(math, write)
abline(lsfit(write, math))

#alternatively
plot(math, write)
fit<-lm(write ~ math)
abline(fit)

# pch for plotting characters, or symbol to use
# see help(points) for more information on pch

for hsb2_female<-hsb2[female==1,]
hsb2_male<-hsb2[female==0,]
with(hsb2_female, plot(math, write, pch=20, col="darkred"))
with(hsb2_male, points(math, write, pch=22, col="darkblue"))

# alternatively 
math_male<-hsb2$math[female==0]
write_male<-hsb2$write[female==0]
math_female<-hsb2$math[female==1]
write_female<-hsb2$write[female==1]

plot(math_female, write_female, type="p", 
     pch=20, col="darkred")
points(math_male, write_male, pch=22, col="darkblue")

# adding legend 

hsb2_female<-hsb2[female==1,]
hsb2_male<-hsb2[female==0,]
with(hsb2_female, plot(math, write, pch=20, 
     col="darkred", ylim=c(25, 70)))
with(hsb2_male, points(math, write, pch=22, 
     col="darkblue"))
legend(65, 35, c("female", "male"), pch=c(20, 22), 
       cex=.8, col=c("darkred", "darkblue"))

math_male<-hsb2$math[female==0]
write_male<-hsb2$write[female==0]
math_female<-hsb2$math[female==1]
write_female<-hsb2$write[female==1]

plot(math_female, write_female, type="p", pch=20,
     col="darkred", ylim=c(25, 70))
points(math_male, write_male, pch=22, col="darkblue")
abline(lsfit(write_female, math_female), col="darkred")
abline(lsfit(write_male, math_male), col="darkblue")
legend(65, 35, c("female", "male"), pch=c(20, 22), 
       cex=.8, col=c("darkred", "darkblue"))