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Old June 3rd, 2010, 07:32 PM posted to microsoft.public.access.tablesdbdesign
Steve[_77_]
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Posts: 1,017
Default db design to calculate overlap in group membership in time

Hi Liz,

I think that the first thing is to answer two questions ...
1. "....one bird is in the same group as another bird" implies that you
can identify individual birds. Can you do that and what are the
characteristics (fields) that can be used to uniquely identify a bird?

2. What factors (fields) distinguishes one group from another. For
example, Bird A and Bird B are together; is that a group? At another spot,
Bird C and Bird D are together; is that a group? After a few moments, Bird C
and Bird D join Bird A and Bird B. There are now four birds together, is
that group AB, Group CD or a new group.

Steve


"EHobs" u60556@uwe wrote in message news:a8fac2069ea04@uwe...
Hi all,

I am a biologist studying the social structure of birds. I am currently
brainstorming ideas for constructing a database that will allow me to
easily
calculate the number of seconds that one bird is in the same group as
another
bird. Because group membership changes frequently with birds arriving and
departing at different times, and often arriving, departing, and
re-arriving
on the scale of seconds, I will have many thousands of records. I am
trying
to determine how to best set up this database before entering all the
data. I
have 2 goals with this database:

1) I need to find a way that I can streamline data entry. I was thinking
3
columns: ID, time of movement, and whether it is an arrival or departure.
Because of the frequent movements and the large number of potential
individuals, I need to be able to enter arrivals and departures
separately.

2) I need to determine how I am going to calculate the amount of time that
any 2 birds at present at the same time. This needs to be able to account
for
individuals that arrive and depart at different times, and calculate just
"shared" time.

I think this problem may be somewhat similar to company records of
employees
hired and fired at different dates, where the amount of time of overlap in
employment is calculated.

Any help or advice would be greatly appreciated!

Thanks,

Liz