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st: Compare rate of change in proportion with time in 2 groups
From
Quinn Leigh <[email protected]>
To
[email protected]
Subject
st: Compare rate of change in proportion with time in 2 groups
Date
Thu, 2 Jun 2011 14:55:28 +1000
Dear all,
I'm very new to STATA and have limited statistical knowledge. I have a
set of grouped data which looks like this
year sex Disease_A Disease_B Total
1991 1 10 1 11
1992 1 16 3 19
1993 1 20 9 29
1994 1 10 7 17
1995 1 15 13 28
1996 1 22 16 38
1991 2 3 2 5
1992 2 5 0 5
1993 2 5 0 5
1994 2 7 1 8
1995 2 9 2 11
1996 2 5 3 8
The data shows that the total number of both Disease_A and Disease_B
have increased with time. Sex=1 (male) is more common in both
Disease_A and Disease_B. My question is, how do I find out whether the
proportion of male:female changed with time (eg. the proportion of
male is 60% in 1991 and increased to 70% in 1996), and if they have
changed, whether Disease_A and Disease_B have different rates of
change in proportion (eg. the proportion of male increased faster in
Disease_A compared to Disease_B, from 60% to 70% in disease_A compared
to from 70% to 75% in disease_B)?
I attempt to use blogit function (blogit Disease_A Total sex year) but
I'm not quite sure of the results because if a small p-value (eg.
0.03) for 'year' is obtained, would it be a result of increased number
of cases with time, not increased proportion?
Thanks you.
Regards,
Quinn
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