Re: st: Tracking Replacements Made to Variables

[Daniel Feenberg <feenberg@nber.org>]

On Mon, 31 Jan 2011, Christopher Lanoue wrote:

> Hi,
> My problem is that I am trying to keep track of changes that I make to
> my data using STATA. For instance if I have data such as:
>
> yr        var1
> 1961    15
> 1962     .
> 1963    20
> 1964     .
> 1965    30
>
> and I want to take the average of the two data points to fill in the
> missing values.
>
> I run replace var1 = (var1[_n-1]+var1[_n+1])/2 if var1 == . to
> accomplish this task, but STATA simply outputs (2 changes made) to the
> display. Is there any way to capture the changes STATA makes, i.e.
> loop through the changes (if the changes are saved somewhere) and
> output something like "var 1, year 1962. Average of 1961 and 1963."?
> If this is not possible, is there are a way to use subscripts on the
> variable so that I can loop through each value and if a change is
> made, output the string above, i.e. replace var1[`i'] = .... and then
> display "var 1, yr[`i']. Average of yr[`i'-1] and yr[`i']+1."
> Any help would be greatly appreciated.

Save a copy of the variable and then list the values that are different:

  gen save = var1
  replace var1 = ...
  list var1 save if var1 != save
  drop save

Daniel Feenberg

> Thanks in advance,
> Chris
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