st: mi may not be combined with by

[Paul von Hippel <paulvonhippel.utaustin@gmail.com>]

The following command
 bysort dataset: mi impute reg x y, add(5)
returns the following error:
 mi may not be combined with by
Are there other ways to do what I think the command should do here?
Many thanks for any suggestions.

Some background: I have simulated 60 incomplete hundred-row datasets,
stacked one on top of the other in a Stata data file. The variables
are x and y, and the datasets are indexed by a third variable called
dataset. Like this:

. list dataset x y

       +----------------------------------+
       | dataset           x            y |
       |----------------------------------|
    1. |       1   2.2345289   -22.217398 |
    2. |       1           .   -21.833361 |
    3. |       1   4.6491754   -17.114244 |
<snip>
  101. |       2   6.5433351   -17.183628 |
  102. |       2           .   -13.853756 |
  103. |       2           .   -13.690219 |
<etc>


--
Best wishes,
Paul von Hippel
Assistant Professor
LBJ School of Public Affairs
Sid Richardson Hall 3.251
University of Texas, Austin
2315 Red River, Box Y
Austin, TX  78712

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