/* This is monthly influenza data taken from Robert H. Shumway,
   APPLIED STATISTICAL TIME SERIES ANALYSIS, 1988, p. 194.  The
   table is labeled "Country X  Monthly Cases of Influenza for 10
   Years (1965 - 1974)."  */

options pagesize=60 linesize=74 nodate;
goptions device=win
gsfname=plot
rotate=landscape
gsfmode=append
target=hpljs3;
*border;


data influ;
   format date monyy5.;
   input date:monyy5. flu @@;
   cards;
jan65   633 feb65   488 mar65   852 apr65  1097 may65  2447 jun65  8111
jul65 16483 aug65 25156 sep65 11980 oct65  7294 nov65  1284 dec65  4674
jan66  3084 feb66   878 mar66  1267 apr66  2530 may66  3175 jun66  3709
jul66  5180 aug66 14263 sep66 10244 oct66 13688 nov66 10277 dec66  6370
jan67  1718 feb67  1474 mar67  2277 apr67  4535 may67  7467 jun67 10791
jul67  7217 aug67 21100 sep67 14033 oct67 21953 nov67  9706 dec67  2782
jan68  2818 feb68  1150 mar68  2276 apr68  4388 may68 27559 jun68 50000
jul68 27650 aug68 31580 sep68 13729 oct68 11441 nov68  3410 dec68  1336
jan69   988 feb69  1055 mar69  2467 apr69  4867 may69  8718 jun69 38448
jul69 35590 aug69 32118 sep69 18391 oct69 11253 nov69  4912 dec69  2190
jan70  1287 feb70  1106 mar70  2092 apr70  5019 may70  7269 jun70 11145
jul70 25515 aug70 25434 sep70 24076 oct70  9605 nov70  5566 dec70  3765
jan71  1697 feb71  1666 mar71  4097 apr71  5808 may71  8963 jun71 17291
jul71 15885 aug71 14330 sep71 14522 oct71  8184 nov71  5956 dec71  4454
jan72  2005 feb72  1990 mar72  3021 apr72  4950 may72  8227 jun72  8251
jul72 15161 aug72 20986 sep72 11168 oct72  5794 nov72  4310 dec72  4102
jan73  2377 feb73  2240 mar73  4245 apr73  6452 may73 15736 jun73 25880
jul73 21354 aug73 26784 sep73 12722 oct73 12353 nov73  7182 dec73 11419
jan74  2563 feb74  2691 mar74  3853 apr74  6326 may74  9362 jun74 10685
jul74 13148 aug74 39093 sep74 19720 oct74 16492 nov74  7035 dec74 12224
;

title 'Influenza in Country X by Month Jan. 1965 - Dec. 1974';

axis1 label=('Year');

axis2 order=(0 to 60000 by 5000)
      label=(angle=90 'Cases of Influenza');

proc gplot data=influ;
   plot flu*date / haxis=axis1 vaxis=axis2;
   symbol1 i=join;
   format date year4.;

run;

/*  Here we use the autocorrelation function to try to uncover signs of
    seasonality in flat (non-trending) data.  Notice that we do not difference the data
    before examining the autocorrelation functions for the spikes at the
    seasonal lags j = 12, 24, 36, and 48 because the data does not have
    any slope to it (i.e. it is flat).  */

proc arima data = influ;
  identify var=flu nlag=48;
  
  run;