/*****************************************************************************************************************

SAS file name: Index_Centiles
File location: 
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Purpose: To demonstrate how to alter the behaviour of SAS index centiles with PROC DATASETS.
Author: Peter Clemmensen
Creation Date: 18/03/2018

This program supports the example page "The Importance Of SAS Index Centiles" on SASnrd.com

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/* Example Data */
data MyData;
   length ID 8 first_name $20 last_name $20 gender $1 state $20 birth_date 6 children 3;
 
   array first_namesm{20}$20 _temporary_ ("Paul", "Allan", "Bob", "Michael", "Chris", "David", "John", "Jerry", "James", "Robert",
                                       "William", "Richard", "Thomas", "Daniel", "Paul", "George", "Larry", "Eric", "Charles", "Stephen");
   array first_namesf{20}$20 _temporary_ ("Mary", "Linda", "Patricia", "Barbara", "Elizabeth", "Maria", "Susan", "Margaret", "Lisa", "Nancy",
                                       "Karen", "Betty", "Helen", "Sandra", "Sharon", "Laura", "Michelle", "Angela", "Melissa", "Amanda");
   array last_names{20}$20 _temporary_ ("Smith", "Johnson", "Williams", "Jones", "Brown", "Miller", "Wilson", "Moore", "Taylor", "Hall",
                                      "Anderson", "Jackson", "White", "Harris", "Martin", "Thompson", "Robinson", "Lewis", "Walker", "Allen");
   array states{50}$20 _temporary_ ("Alabama", "Alaska", "Arizona", "Arkansas", "California", "Colorado", "Connecticut", "Delaware", "Florida", 
                                "Georgia", "Hawaii", "Idaho", "Illinois", "Indiana", "Iowa", "Kansas", "Kentucky", "Louisiana", "Maine",
                                "Maryland", "Massachusetts", "Michigan", "Minnesota", "Mississippi", "Missouri", "Montana", "Nebraska", 
                                "Nevada", "New Hampshire", "New Jersey", "New Mexico", "New York", "North Carolina", "North Dakota", "Ohio", 
                                "Oklahoma", "Oregon", "Pennsylvania", "Rhode Island", "South Carolina", "South Dakota", "Tennessee", "Texas", 
                                "Utah", "Vermont", "Virginia", "Washington", "West Virginia", "Wisconsin", "Wyoming");
 
   call streaminit(123);
 
   do ID=1 to 10e7;
      if rand("Uniform")<0.5 then do;
         gender="M";
         first_name=first_namesm[ceil(rand("Uniform")*20)];
      end;
      else do;
         gender="F";
         first_name=first_namesf[ceil(rand("Uniform")*20)];
      end;
      last_name=last_names[ceil(rand("Uniform")*20)];
      state=states[ceil(rand("Uniform")*50)];
      birth_date=rand("Integer", '01jan1950'd, '01jan1990'd);
      children=rand("Table", 0.1, 0.2, 0.3, 0.2, 0.1, 0.1)-1;
      output; 
   end;
 
   format birth_date date9.;
run;

/* Create simple index */
proc datasets library=work nolist;
   modify MyData;
      index delete _all_;
      index create idx=(first_name last_name) / nomiss updatecentiles=10;
run;quit;

/* Review centiles */
proc contents data=MyData centiles;
run;

/* Refresh Centiles */
proc datasets library=work nolist;
   modify MyData;
      index centiles idx / refresh;
run;quit;