[Babase] Interpolation, is it self-censoring? Please review
Karl O. Pinc
babase@www.eco.princeton.edu
Sat, 23 Jul 2005 21:49:26 +0000
Ok. I will go ahead and have the new system work like the
foxpro system: it will interpolate after the last census,
and so make MEMBERS rows after the statdate, when and
only when the individual
is alive and there's another, later, census.
Documentation on interpolation is forthcoming and will detail
everything. Then I will then test and ensure my new code works as
documented.
On 07/22/2005 04:55:39 PM, Jeanne Altmann (altj@Princeton.EDU) wrote:
> This sounds right. As I understand it, we must be very sure that the
> first time an individual is not in the group in which it was last
> censused, an absence must be entered. The field team is supposed to
> do this, but the entry person must be alert to do so if the field team
> neglected to. Correct?
Right.
>
> ----- Original Message -----
> From: "Karl O. Pinc" <kop@meme.com>
> Date: Thursday, July 21, 2005 7:01 pm
> Subject: [Babase] Interpolation, is it self-censoring? Please review
>
> > Hi,
> >
> > I'd like a response from Jeanne or Susan before going ahead
> > with the changes to interpolation we discussed over lunch
> > today.
> >
> > In foxpro interpolation works (in part) as follows:
> >
> > 3. The 14 day Interpolation Limit
> >
> > Given no other information, an individual is considered to
> > remain (or have been) in the group where observed for 14 days
> > following (or preceding) the date of observation.
> >
> > Outside of this 14 day range the individual is placed in the
> > unknown group.
> >
> > Clarifications:
> >
> > a. The 14 day Interpolation Limit will not place a row in
> > MEMBERS before an individual's Birth date.
> >
> > b. When an individual is dead, The 14 day Interpolation Limit
> > will not place a row after the individual's Statdate.
> >
> > c. When an individual is alive, The 14 day Interpolation
> Limit
> > will place a row after the individual's Statdate, but only
> > when there is a subsequent absence. Again, as in The
> > Halfway to Absence Interval, the absence must be one
> > recorded for the same group as the previous locating
> > censuses.^[14]
> >
> > ^[14] Note that, as the individual is alive, any censuses that
> > post-date the individual's Statdate must record an absence,
> > else the Statdate would be adjusted to reflect the date of
> > last census.
> >
> >
> > Over lunch we decided that interpolation would never interpolate
> > past an individual's Statdate. However, this
> > change seems to introduce self-censoring.
> > (I knew I had a problem with this when Cathrine
> > and I discussed it earlier, but I didn't recall
> > it over lunch.)
> >
> > First, a review:
> >
> > Rule c keeps interpolation from putting a trailing
> > 14 days of in-the-group onto the end of each
> > individual at the end of each month, until the
> > next census data sheet is entered. Clearly, we don't
> > want such artifacts of the data entry process.
> > This too is a certain amount of self-censoring,
> > but we have unavoidable problems at "the end
> > of time" -- when data entry ceases -- and this is
> > a good a way as any to work around the problem.
> >
> > But a subsequent absence means we're not at
> > "the end of time" for the individual. There
> > has been further data entry.
> >
> > To eliminate interpolation after the Statdate
> > would be self-censoring because the census
> > when the individual was last observed is treated differently
> > from all the other censuses. If the individual is dead,
> > then we don't want to interpolate their last census,
> > but if they just wander off I don't see why we would
> > not interpolate to the subsequent absence just as
> > we do with any other census. The only difference
> > is that they happened to return to the group in the
> > previous censuses. (To speak for Cathrine,
> > she thinks the last census _is_ different
> > because the individual _could_ be dead. But I
> > think that if we thought they were dead
> > we'd mark them dead and do whatever we like
> > with the Statdate to indicate date of death.
> > The ones we don't mark dead should be considered
> > alive (past their Statdate) just like everybody
> > else who's not dead.)
> >
> > This all rang a bell with me because IIRC we
> > introduced the "interpolation after Statdate"
> > the last time we took a serious look at interpolation
> > and made changes (and didn't document them.)
> >
> > Please decide whether we should made this change
> > to the interpolation procedure.
Karl <kop@meme.com>
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