From: Karen Kalumuck (karenk@exploratorium.edu)
Date: Wed Jun 23 2004 - 11:42:29 PDT
Message-Id: <p05010402bcff793102da@[192.168.112.82]> Date: Wed, 23 Jun 2004 11:42:29 -0700 From: Karen Kalumuck <karenk@exploratorium.edu> Subject: Re: pinhole Genetics Questions- for Aim High
Hi Carrie!
To calculate the "uniqueness" of a combination of traits in a class,
do the following:
1) Record how many students in a class exhibit a particular trait.
For example, 2 out of 20 have blue eyes, 5 out of 20 can tongue roll,
15 out of 20 have "hitchhikers thumb", etc.
2) Have each student record the prevalence for each trait as it
refers to themselves.
For example: Anne has: Blue eyes (2/20 or 1/10) and is a
tongue-roller (5/20 or 1/4). She does NOT have hitchhiker's thumb:
5/20 or 1/4. She then multiplies together the three numbers: 1/10 x
1/4 x 1/4 = 1/40 . The probability of any one student in that class
having this combination of traits is 1/160.
This is only based on the distribution of the traits in that
particular class -- so if you found a group of 160 students, applying
this distribution to them, Anne would be the only person with this
combination of traits.
Of course, sample size makes a huge difference - your sample size is
probably small. Additonally, the more traits one has recorded, the
more unique someone will appear.
If you are teaching several classes, it would be fun to combine numbers.
Hope that this helps -- enjoy!
---Karen
-- Karen E. Kalumuck, Ph.D. Biologist/Educator Exploratorium Teacher Institute 3601 Lyon St. San Francisco, CA 94123 415-561-0388 FAX 415-561-0307
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