/************************************************
  How to Set up Missing Values  
      in a SAS Data Set

 FILENAME:  MISSING.SAS
***********************************************/
options formchar="|----|+|---+=|-/\<>*";
options pageno=1 nodate;
title;

/*READ IN RAW DATA. MISSING VALUES HAVE NOT
   BEEN REPLACED BY THE SAS MISSING VALUE CODE */
data owen;
  infile "owen.dat";
  input fam_num childnum age sex race w_rank income_c height 
        weight hemo vit_c vit_a head_cir fatfold b_weight
        mot_age b_order m_height f_height ;  
run;

title "Owen Data. Missing Value Codes Have Not Been Fixed ";
proc means data=owen;
run;




/*MISSING VALUES FOR NUMERIC VARIABLES*/
data owen;
  infile "owen.dat";
  input fam_num childnum age sex race w_rank income_c height 
        weight hemo vit_c vit_a head_cir fatfold b_weight
        mot_age b_order m_height f_height ;  

    /*set up missing value codes*/

  if vit_a    = 99 then vit_a    = .;
  if head_cir = 99 then head_cir = .;
  if fatfold  = 99 then fatfold  = .;
  if mot_age  = 99 then mot_age  = .;
  if b_order  = 99 then b_order  = .;

  if height   = 999 then height   = .;
  if weight   = 999 then weight   = .;
  if b_weight = 999 then b_weight = .;
  if m_height = 999 then m_height = .;
  if f_height = 999 then f_height = .;
 run;

title "Owen Data. Missing Value Codes Have Been Replaced by . ";
proc means data=owen;
run;

/*Create a Complete data set*/
data complete;
  set owen;
  if nmiss(of fam_num -- f_height)=0;
run; 
title "Complete Data";
proc means data=complete;
run;


/*MISSING VALUES FOR CHARACTER VARIABLES*/

/*Read in original raw data*/
data test ;
  input name $ sex $ age city $;
  cards;
Gene  M  62 Saginaw
Cyndi F    45 Unk 
Alice  NA  51 Bay City       
Bob   M   55 Unk
    ;
proc print data=test;
  title "Test Data Set with Missing Values Still in Data Set";
run;

/*Set up Missing Value Codes*/
data test ;
  input name $ sex $ age city $;
  if sex = "NA" then sex=' ';
  if city = "Unk" then city = ' ';
  cards;
Gene  M  62 Saginaw
Cyndi F    45 Unk 
Alice  NA  51 Bay City       
Bob   M   55 Unk
    ;
proc print data=test;
  title "Test Data Set with Missing Values Set to ' ' ";
run;