[Babase] One user's suggestion on rank data
Russ Van Horn
rvanhorn at duke.edu
Tue Oct 10 13:07:29 EDT 2006
Hi all,
This may be a bit off the ranker topic, but I have a related
suggestion that I think is worth considering during the discussion of
the ranking system. This comes from the perspective of someone who
uses rank data from time to time, but who doesn't fully understand
the detailed process by which ranks are generated from the
observations of agonistic interactions.
After ranks are assigned, as the ranks are added to BABASE, I think
it would be useful for those conducting analyses with ranks to be
able to assess how much data went into the assignment of those ranks.
At present it's not straightforward for someone like myself to make
such an assessment. Would it be possible to add a new field to what
is now the 'ranks' table in FoxPro, presenting the number of
agonistic interactions used to generate each rank?
Here's why I think it would be worth adding another field, possibly
to 'ranks'. To me, as a user of the system, assigned ranks are
estimated data. Regardless of the type of assigned rank (e.g., ADM,
ALL), and regardless of whether I'm using assigned rank as a
predictor variable or as a response variable, there might be data
points (i.e., ranks) which I might want to treat as more reliable
than others. (I'm proceeding from the assumption that rank can be
more accurately and precisely estimated if more agonistic encounters
were observed.) For example, suppose I conduct an analysis of whether
adult male rank influenced the probability of secondary dispersal, or
the probability of predation on gazelle fawns, or the probability of
paternity, etc. Whatever the response variable, I might find that
rank was a good predictor during most time periods or for most males,
but that rank wasn't a good predictor for some time periods or males.
If all adult male ranks were based on comparable numbers of observed
agonistic encounters, then I might plausibly try to identify factors
other than rank that might be influencing secondary dispersal, or
predation, or paternity, etc. However, if the predictive power of
rank was low only during time periods, or for males, for which there
weren't many observed agonistic encounters, then the possibility
exists that I'm seeing a spurious result, and that the general
predictive model is valid. (And, that I should kick myself for not
including sample size as a covariate.) At present it's difficult for
users not involved with rank generation to determine whether, in
fact, all ranks are created equal.
Cheers,
Russ
--
......................................................................................................
R. C. Van Horn, Ph.D.
Research Associate
Department of Biology
Box 90338 phone: 919-660-7297, 660-7306
Duke University email: rvanhorn at duke.edu
Durham, NC 27708-0338 web: http://www.duke.edu/~rvanhorn
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