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Statistics版 - Poisson and Binomial

ANOVA model 中 CELL count 过小到底对model有什么影响请问poisson regression和 Log-linear model之间的联系？

a question about proc genmodGEE model一问

 1 (共1页)
h**l

1
I am trying to compare the academic performance of 2 groups of students. the
dependent variable is the “number of passes on assessments”. The students
take a varied number of assessments ranging anywhere from 5 to 12. I think
it's a binomial distribution. But would Poisson regression work? What are
the essential differences between Poisson and Binomial? Are they equivalent
in this case?
s*********e

2
do you mean "negative binomial" ^_^?
standard Poisson definitely won't work, since your outcomes range from 5 to
12. however, truncated poisson might.
h**l

3
Thanks. So basically students can fail maximally 5 tests and then they'll be
kicked out.
So the study will have 12 tests, most of the students will fail less than 5
tests so the odds ratio would be # of failed tests/ 12. But for those who're
kicked out, the odds ratio would be 5/# tests they take. In this case, it's
negative binomial?
well, so I think I should use proc GENMOD? how do you perform logistic
regression of negative binomial variables?
Thanks a lot.

to

【在 s*********e 的大作中提到】
: do you mean "negative binomial" ^_^?
: standard Poisson definitely won't work, since your outcomes range from 5 to
: 12. however, truncated poisson might.

s*********e

4
what exactly is the objective of your study?
with binomial, you are trying to predict the probability to pass all 12 exams.
with poission / nb, you are trying to predict the number of exams passed.
h**l

5
The objective of the study is to compare the academic performance of 2
groups of students. The tricky part is that there are students who failed 5
tests and dropped out immediately after they failed 5. We don't want to
exclude these students who didn't have chance to take all 12 exams.

exams.

【在 s*********e 的大作中提到】
: what exactly is the objective of your study?
: with binomial, you are trying to predict the probability to pass all 12 exams.
: with poission / nb, you are trying to predict the number of exams passed.

b***t

6
multinomial
h**l

7
well, each test can only have two outcomes: pass and fail... it's just that
the students can have different number of tests depending on if they pass or
not, and the number has a minimum of 5 and maximum of 12.

【在 b***t 的大作中提到】
: multinomial
x*******i

8
multimomial. 我也认为是。
the number of passed in some fix number of total test.

x*******i

9

h**l

10
no...
Multinomial has k outcomes. When k=2, multinomial=binomial.
So binomial is like flipping a coin
and multinomial is like throwing a die.

【在 x*******i 的大作中提到】
: multimomial. 我也认为是。
: the number of passed in some fix number of total test.
: 不是poisson。 poisson没有上线。

n*******m

11
n*******m

12
BTW, if a student quits whenever he fails 5 times, it's no longer a binomial
distr or multinomial. Use the negative binomial as the link will work.
h**l

13
Does negative binomial have infinite tests until the students fail 5 test?

binomial

【在 n*******m 的大作中提到】
: BTW, if a student quits whenever he fails 5 times, it's no longer a binomial
: distr or multinomial. Use the negative binomial as the link will work.

W**********E

14

but lamd/offset)。 Y/OUTCOME就是错误的次数，OFFSET 就是总共经历过的测试。打

n*******m

15

x*******i

16

multinomial 和binomial一回事。
 1 (共1页)

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ANOVA model 中 CELL count 过小到底对model有什么影响请问poisson regression和 Log-linear model之间的联系？