Connecting the points to the regression line

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Suppose the following database: 

Income <- structure(list(X = 1:30, Education = c(10, 10.4013377926421, 
10.8428093645485, 11.2441471571906, 11.6454849498328, 12.0869565217391, 
12.4882943143813, 12.8896321070234, 13.2909698996656, 13.7324414715719, 
14.133779264214, 14.5351170568562, 14.9765886287625, 15.3779264214047, 
15.7792642140468, 16.2207357859532, 16.6220735785953, 17.0234113712375, 
17.4648829431438, 17.866220735786, 18.2675585284281, 18.7090301003344, 
19.1103678929766, 19.5117056856187, 19.9130434782609, 20.3545150501672, 
20.7558528428094, 21.1571906354515, 21.5986622073579, 22), Income = c(26.6588387834389, 
27.3064353457772, 22.1324101716143, 21.1698405046065, 15.1926335164307, 
26.3989510407284, 17.435306578572, 25.5078852305278, 36.884594694235, 
39.666108747637, 34.3962805641312, 41.4979935356871, 44.9815748660704, 
47.039595257834, 48.2525782901863, 57.0342513373801, 51.4909192102538, 
61.3366205527288, 57.581988179306, 68.5537140185881, 64.310925303692, 
68.9590086393083, 74.6146392793647, 71.8671953042483, 76.098135379724, 
75.77521802986, 72.4860553152424, 77.3550205741877, 72.1187904524136, 
80.2605705009016)), .Names = c("X", "Education", "Income"), class = "data.frame", row.names = c(NA, 
-30L))

To graph the LOESS line in gpplot2 , simply run the following command: 

ggplot(Income, aes(Education, Income)) + geom_point(color="red") + geom_smooth(se=FALSE)

However, how do you connect the points to the regression line to illustrate the error term (as shown in the graph below)?

Based on the question I asked in SOEN.

    
asked by anonymous 02.04.2014 / 14:51

2 answers

5

You can also use the plot function 

mod <- loess(Income ~ Education, data = Income)
Income <- transform(Income, Fitted = fitted(mod))

plot(Income ~ Education, data = Income, type = "p", col = "red",
    cex = 1.25)
lines(Fitted ~ Education, data = Income, col = "blue")
with(Income, segments(Education, Income, Education, Fitted))

    
02.04.2014 / 15:08
3

In ggplot2 you can use geom_segment to draw lines between points and values predicted by the model. But first you need to rotate the model "out" of gpplot2 to get the values you expect.

Running the template and adding a column to the database: 

require("ggplot2")

mod <- loess(Income ~ Education, data = Income)
Income <- transform(Income, Fitted = fitted(mod))

Adding the rows to the chart: 

ggplot(Income, aes(Education, Income)) + 
  geom_point(color="red") + 
  geom_smooth(se=FALSE, method = "loess") +
  geom_segment(aes(x = Education, y = Income,
                   xend = Education, yend = Fitted))

    
02.04.2014 / 14:58
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