SAS programming of linear thresholds for continuous variables

[Epidemiologist]

Hello,

I want to program linear thresholds for continuous variables. In my case, it means that if the values of variable A are <=30, then these values shall be put (placed) as 30. Otherwise the variable A shall be applied.

Therefore my code is:

A=A_t30;
if A_t30<=30 then A_t30=30;

Then all values of variable A_t30 are placed as 30. Mean is 30; SD is 0; Minimum is 30; Maximum is 30.

Do you know my mistake?

I am glad if you can help me. Thank you very much.

Kind regards

[ballardw · Accepted solution]

Show some example data, some with problem values and some without. And the entire code used.

If A_t30 does not exist prior to executing this statement:

A = A_t30;

Then you created a variable A_t30 and all values were missing. So since missing is treated as < 30 it gets set to 30.

Perhaps you intended to use

A_t30 = A;

assigning the value of the variable A to A_t30 before the test.

The receiving side of value assignment is always the left of the = sign.

[Epidemiologist]

Thank you very much. It was very helpful. 🙂