Let's create a scatterplot relating height and weight before treatment, along with both points and a smooth curve using
geom = c("point","smooth"). In
qplot, the default smoother is LOWESS, and the gray band represents a standard error confidence interval. LOWESS fits models to local subsets of the variables to produce a smoothed version of the data.
You can read further about LOWESS in various texts and online sources. For this example, we set up the graph as an object (
Y) and plot it by entering the object name on the command line:
Y <- qplot(HEIGHT, WEIGHT_1, data = T, xlab = "HEIGHT (cm)", ylab = "WEIGHT BEFORE TREATMENT (kg)", geom = c( "point","smooth")) Y
Our graph now looks like this:
We have the smoothed curve ...