/*------------------------------------------------------------
|  Code1_1                                                    |
|    Dates: Internally they are numbers 0=Jan 1, 1960         |
|    lag5(Y) is Y from 5 observations ago.                    |
|    Defining your F12 key                                    |
|       (1)  Tools-> Options -> Keys                          |
|       (2)  At F12 type the following:                       |
|             log; clear; out; clear; wpgm; sub;              |
|       (3)  x - Close the Keys window                        |
 ------------------------------------------------------------*/

title " "; footnote " "; goptions reset=all; 
axis1 label=(angle=90 font=centb h=1.8) offset=(2,2); 
* libname fets  
"C:\Documents and Settings\dickey\Desktop\FETS\Data";

* (1) Check that data sets are OK; 
proc contents data=fets._all_ nods; run; 

* (2) Read and plot the data; 
data one; set fets.dotair9497;     
 stored = date;  
 days = date- '01dec1993'd;    * SAS date constant; 
proc print data=one(obs=30); run; 

proc gplot data=one; 
  plot passengers*date/vaxis=axis1;; 
   symbol1 v=none i=join c=red; 
   title "Airline"; 
run; 


* (3) Place Forecasts at proper Dates; 
Data two; set one; drop passengers stored days;
  slope12 = passengers-lag12(passengers); * 12 month change ; 
  forecast12 = passengers + slope12;
  Method1 = passengers*(passengers/lag12(passengers)); 
  if date > '01dec1994'd then do; 
  date = intnx('month',date,12);   * Bump date up by 12;
  keep date forecast12 Method1;
  end; 
  proc print data=two(obs=30); run; 

Data three; merge one two;  by date; 
proc print data=three(obs=30); run; 
 

* (4) Add the forecasts to plots; 
 proc gplot; plot (passengers Forecast12 Method1)*date/
   overlay vaxis=axis1 legend; 
   title "Simple Forecast"; 
   symbol2 v=dot i=join c=black; 
   symbol3 v=diamond i=join c=green h=1.9; 
   format passengers comma10.; run; 
 
 * (5) Show linear trend Forecast; 
 Proc reg data=three; model Passengers=date; 
 output out=out1 predicted = reg; run; 
 proc print data=out1; where date = "01jan1998"d; run; 
 proc gplot; plot (passengers reg)*date/overlay; 
 symbol2 v=none i=join; 
 run; quit; 
 title " "; footnote " ";