Calculation with lag

[Kurt_Bremser]

In the first observation, DeltaEAs is set to zero, and the SUM function in the last statement of the data step will also set EAs_avant to zero (sum of a missing value and zero).

Then, in all observations where MT_EVT is negative (which it is in your example dataset), this formula is calculated:

DeltaEAs=EAs_avant*(MT_EVT/MT_EA_AVMVT)

Since EAs_avant is zero, the result of this is also zero.

So the SUM of EAs_avant (0) and DeltaEAs (0) will still be zero.

And so the zero perpetuates throughout your dataset.

[SASdevAnneMarie]

Thank you Kurt ! I understood.
Have I nice day !

Marie