title "The leaning tower of pisa";
data pisa;
input year lean;
label lean = "lean in tenths of millimiter";
datalines;
75 642
76 644
77 656
78 667
79 673
80 688
81 696
82 698 
83 713
84 717
85 725
86 742
87 757
;
proc gplot;
plot year*lean;
run;
* Regression analysis;
* to estimate the rate of lean increase per year;
proc reg;
model lean=year;
plot lean*year/pred;
plot lean*year/conf;
plot residual.*year;
plot student.*year;
plot npp.*residual.;
run;