Hi @mkeintz ,
I can see how the sentence you noted in the documentation might be confusing. Let me see if I can clarify it...
For this particular case, where there was:
no frequency conversion,
no missing value interpolation,
the transformation was a simple lag (or lead) transformation, and
the METHOD=NONE option was not specified,
the final results should be the same regardless of whether you use the TRANSFORMOUT= option or the TRANSFORMIN= option. This is because the cubic spline function is fit through the exact same data values in both cases.
For other cases, such as when frequency conversion is being done or when missing values are present in the data, you would expect to see differences if you use the TRANSFORMIN= option rather than the TRANSFORMOUT= option.
If no frequency conversion or missing value interpolation is required, and all you want to do is perform the requested transformation on the values in the DATA= data set, then it is best to use the METHOD=NONE option in this case.
I hope this helps!
DW
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