attach(wages1833)
plot(mwage~age,ylim=range(c(mwage,fwage[fwage>0])))
points(fwage[fwage>0]~age[fwage>0],pch=15,col="red")
lines(lowess(age,mwage))
lines(lowess(age[fwage>0],fwage[fwage>0]),col="red")
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