Better understanding of IF/THEN-DO

[armoore]

I am having trouble understanding why " OR " is used instead of " AND " for Step 3.

The Question Asked:

• Step 1:
• create a temporary data set, cleandata36.
• In this data set, convert all group values to upper case.
• Then keep only observations with group equal to 'A' or 'B'.

• Step 2:
• Determine the MEDIAN value for the Kilograms variable for each group (A,B) in the cleandata36 data set. Round MEDIAN to the nearest whole number.

• Step 3:
• create results.output36 from cleandata36
• Ensure that all values for variable Kilograms are between 40 and 200, inclusively.
• If the value is missing or out of range, replace the value with the MEDIAN Kilograms value for the respective group (A,B) calculated in step 2.

Step 1: 
data work.cleandata36;
  set cert.input36;
  group=upcase(group);
  if upcase(group) in ('A','B');
run;

Step 2:
proc means data=work.cleandata36 median;
class group;
var kilograms;
run;

Step 3:
data results.output36;
  set cleandata36;
  if Kilograms < 40 OR Kilograms > 200 then do;
  if group='A' then kilograms=79;
  else kilograms=89; 
end;
run;

[Shmuel · Accepted solution]

You are relating to next statement:

if Kilograms < 40 OR Kilograms > 200 then do;

Remember that KILOGRAMS is just a variable and one value at a time.

None value can be <40 and >200 at the same time. but it can be

either <40 or >200 at this current observation. 

[Kurt_Bremser]

What you want is either this:

if Kilograms ge 40 and Kilograms le 200

or this

if 40 le Kilograms le 200