Documentation Example 1 for PROC VARIOGRAM

/****************************************************************/
/*          S A S   S A M P L E   L I B R A R Y                 */
/*                                                              */
/*    NAME: VROEX1                                              */
/*   TITLE: Documentation Example 1 for PROC VARIOGRAM          */
/* PRODUCT: STAT                                                */
/*  SYSTEM: ALL                                                 */
/*    KEYS: spatial analysis, semivariogram, model fitting      */
/*   PROCS: VARIOGRAM                                           */
/*    DATA:                                                     */
/*                                                              */
/* SUPPORT: alkolo                                              */
/*     REF: PROC VARIOGRAM, EXAMPLE 1                           */
/*    MISC:                                                     */
/****************************************************************/

title 'Semivariogram Model Fitting of Log-Arsenic Concentration';

data logAsData;
   input East North logAs @@;
   label logAs='log(As) Concentration';
   datalines;
193.0 296.6 -0.68153   232.6 479.1  0.96279   268.7 312.5 -1.02908
 43.6   4.9  0.65010   152.6  54.9  1.87076   449.1 395.8  0.95932
310.9 493.6 -1.66208   287.8 164.9 -0.01779   330.0   8.0  2.06837
225.7 241.7  0.15899   452.3  83.4 -1.21217   156.5 462.5 -0.89031
 11.5  84.4 -0.24496   144.4 335.7  0.11950   149.0 431.8 -0.57251
234.3 123.2 -1.33642    37.8 197.8 -0.27624   183.1 173.9 -2.14558
149.3 426.7 -1.06506   434.4  67.5 -1.04657   439.6 237.0 -0.09074
 36.4 175.2 -1.21211   370.6 244.0  3.28091   452.0  96.5 -0.77081
247.0  86.8  0.04720   413.6 373.2  1.78235   253.5 291.7  0.56132
129.7 111.9  1.34000   352.7  42.1  0.23621   279.3  82.7  2.12350
382.6 290.7  0.86756   188.2 222.8 -1.23308   382.8 154.5 -0.94094
304.4 309.2 -1.95158   337.5 387.2 -1.31294   490.7 189.8  0.40206
159.0 100.1 -0.22272   245.5 329.2 -0.26082   372.1 379.5 -1.89078
417.8  84.1 -1.25176   173.9 407.6 -0.24240   121.5 107.7  1.54509
453.5 313.6  0.65895   143.5 346.7 -0.87196   157.4 125.5 -1.96165
371.8 353.2 -0.59464   358.9 338.2 -1.07133     8.6 437.8  1.44203
395.9 394.2 -0.24144   149.5  58.9  1.17459   453.5 420.6 -0.63951
182.3  85.0  1.00005    21.0 290.1  0.31016    11.1 352.2 -0.88418
131.2 238.4 -0.57184   104.9   6.3  1.12054   247.3 256.0  0.14019
428.4 383.7  0.92448   327.8 481.1 -2.72543   199.2  92.8 -0.05717
453.9 230.1  0.16571   205.0 250.6  0.07581   459.5 271.6  0.93700
229.5 262.8  1.83590   370.4 228.6  2.96611   330.2 281.9  1.79723
354.8 388.3 -3.18262   406.2 222.7  2.41594   254.4 393.1  2.03221
 96.7  85.2 -0.47156   407.2 256.8  0.66747   498.5 273.8  1.03041
417.2 471.4 -1.42766   368.8 424.3 -0.70506   303.0  59.1  1.43070
403.1 264.1  1.64554    21.2 360.8  0.67094   148.2  78.1  2.15323
305.5 310.7 -1.47985   228.5 180.3 -0.68386   161.1 143.3  1.07901
 70.5 155.1  0.54652   363.1 282.6 -0.43051    86.0 472.5 -1.18855
175.9 105.3 -2.08112    96.8 426.3  1.56592   475.1 453.1 -1.53776
125.7 485.4  1.40054   277.9 201.6 -0.54565   406.2 125.0 -1.38657
 60.0 275.5 -0.59966   431.3 494.6 -0.36860   399.9 399.0 -0.77265
 28.8 311.1  0.91693   166.1 348.2 -0.49056   266.6  83.5  0.67277
 54.7 356.3  0.49596   433.5 460.3 -1.61309   201.7 167.6 -1.40678
158.1 203.6 -1.32499    67.6 230.4  1.14672    81.9 250.0  0.63378
372.0  50.7  0.72445    26.4 264.6  1.00862   300.1  91.7 -0.74089
303.0 447.4  1.74589   108.4 386.2  1.12847    55.6 191.7  0.95175
 36.3 273.2  1.78880    94.5 298.3 -2.43320   366.1 187.3 -0.80526
130.7 389.2 -0.31513    37.2 324.2  0.24489   295.5 211.8  0.41899
 58.6 206.2  0.18495   346.3 142.8 -0.92038   484.2 215.9  0.08012
451.4 415.7  0.02773    58.9  86.5  0.17652   212.6 363.9  0.17215
378.7 407.6  0.51516   265.9 305.0 -0.30718   123.2 314.8 -0.90591
 26.9 471.7  1.70285    16.5   7.1  0.51736   255.1 472.6  2.02381
111.5 148.4 -0.09658   440.4 375.0  1.23285   406.4  19.5  1.01181
321.2  65.8 -0.02095   466.4 357.1 -0.49272     2.0 484.6  0.50994
200.9 205.1  0.43543    30.3 337.0  1.60882   297.0  12.7  1.79824
158.2 450.7  0.05295   122.8 105.3  1.53936   417.8 329.7 -2.08124
;

ods graphics on;


/* Exploratory analysis of log-Arsenic data --------------------*/

proc variogram data=logAsData plots=pairs(mid);
   compute novariogram nhc=50;
   coord xc=East yc=North;
   var logAs;
run;

proc variogram data=logAsData plots(only)=semivar;
   compute lagd=5 maxlag=40;
   coord xc=East yc=North;
   var logAs;
run;



/* Fitting and Selection of a Semivariance Model ---------------*/

proc variogram data=logAsData plots(only)=fit;
   store out=SemivAsStore / label='LogAs Concentration Models';
   compute lagd=5 maxlag=40;
   coord xc=East yc=North;
   model form=auto(mlist=(exp,gau,mat) nest=1 to 2);
   var logAs;
run;

ods graphics off;