The phrase "as substantively" is correct and usable in written English.
It can be used when discussing the depth or significance of a topic or argument in a comparative context.
Example: "The two proposals differ not only in their approach but also as substantively in their expected outcomes."
Alternatives: "in a meaningful way" or "in a significant manner".
The union also sought to get ahead of Mr. Cuomo's cuts rhetorically as well as substantively.
Since the new constitution went into effect, Constitutional Court did declare a number of other laws unconstitutional as substantively inconsistent with the principles of the new constitution, including two of the now-nullified former constitutional amendments.
Well, the main answer is stronger regulation; but it would also be a very good idea, politically as well as substantively, for the Senate to use reconciliation to put the public option back into its bill.
This strikes me as substantively right and politically shrewd, but it's not the whole story.
However, the outcome of the method effect indicates that differences in responses to negatively worded items are worth studying in their own right, and not just as substantively irrelevant artefact/noise that are theoretically uninteresting and need to be eliminated (cf. Marsh 1996).
Similarly, Choice: Current Reviews for Academic Libraries described the author's research as "substantively important", and Library Journal called it "a sociological analysis for the serious student, with all the appropriate scholarly apparatus".
Even "a new era of responsibility" was politically as well substantively problematic, since it equated the underwater homeowner with the C.D.O.
Given his record, his departure would be important substantively as well as symbolically.
He travels all over, constantly; he memorizes dozens of arcane facts, so we can understand their significance; he writes his remarks so well that he can riff on them substantively as well as rhetorically.
That is why the drive for child rights has never faltered - and with your help, substantively as well as financially, we will accelerate that drive when the Special Session on Children finally convenes in May.
Unfortunately, it is not shown as being substantively related to the ISC context.
