G14.5

Anscombe's quartet."Graphs are essential to good statistical analysis." So starts a 1973 article by Anscombe. This article demonstrates why it is important to look at the data before analyzing it numerically.

Table 14.10 contains four different datasets. Each of the datasets produces these identical numerical results: n=11, xbar=9.0, ybar=7.5, r=0.82, y-hat=3+0.5X, P=0.0022.

\fd his- 13 Data set II North 12 10 L there what O AN o lese OH NWAVINODOFN O id NWAUG 10 15 20 0 2 5 4 6 8 10 12 14 16 18 20 X1 X2 Data set III Data set IV 13 12 2 7 11 10 - 10 - O 9 8 Ya -NWA UI N w O TTTTT 0 2 4 6 8 10 12 14 16 18 20 0 2 4 6 8 10 12 14 16 18 20 X3 XA FIGURE 14.17 Anscombe's quartet, Exercise 14.5