data air; set sashelp.air end=eof; 
m = month(date); 
LogPsngr=log(air);output;
if eof then do lead=1 to 12; 
  air=.; logPsngr=.; date=intnx("month",date,1);
  m=month(date);  
  output;end;  
proc print data=air(firstobs=130); run;

proc glm data=air; class m; 
model LogPsngr = date m/solution;
output out=out1 predicted=p residual=r
lcl=l ucl=u;  
run; 

goptions reset=all; title " "; footnote " "; 
axis1 label=(angle=90 font=centb h=1.2); 
proc gplot; 
plot (LogPsngr p l u)*date/
     overlay vaxis=axis1 
     href="01dec1960"d chref=blue; 
symbol1 v=none i=join c=black;
symbol2 v=dot c=red i=none h=0.6; 
symbol3 v=none i=join c=green r=2; 
plot r*date=5/vref=0; *** Why 5 ??? **; 
symbol4 v=circle i=needle r=1 c=blue; 
run;