***Program to read in IQ and other test scores;
DATA IQ_AND_TEST_SCORES;
INPUT ID          1-3
      IQ          4-6
   MATH        7-9
   SCIENCE     10-12
      GROUP;
OVERALL=(ID+IQ+SCIENCE)/500;
IF IQ GT 0 AND IQ LE 100 THEN GROUP=1;
ELSE IF IQ GT 101 LE 140 THEN GROUP=2;
ELSE IF IQ GT 140 THEN GROUP=3;
DATALINES;
001128550590
002102490501
003140670690
004115510510
;
PROC PRINT DATA=IQ_AND_TEST_SCORES;
VAR IQ MATH SCIENCE GROUP OVERALL;
BY IQ;
ID ID;
RUN;
SAS程序只发现了ID=001和ID=003的数据。为什么？