由买买提看人间百态

boards

本页内容为未名空间相应帖子的节选和存档,一周内的贴子最多显示50字,超过一周显示500字 访问原贴
Statistics版 - Poisson and Binomial
相关主题
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?
怎么在sas中计算sensitivity,关于genmod?need help SAS Macro
怎么去读proc genmod的output(关于multinomial)请教个问题
请问怎么建立变量全是ordinal data的model?急,谢谢。multinomial distribution: how to derive the covariance of different variable
a question about proc genmodGEE model一问
求助:Power analysis for poisson regression?这种情况应该用什么模型?
一道概率问题.请教个比较slope的问题——包子贴
在sas 里面,poisson regression model里面,response variable可以是binary吗?Gamma distribution for power analysis,请大拿指点
相关话题的讨论汇总
话题: binomial话题: poisson话题: students话题: tests话题: multinomial
1 (共1页)
h**l
发帖数: 4883
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
发帖数: 1051
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
发帖数: 4883
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
发帖数: 1051
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
发帖数: 4883
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
发帖数: 348
6
multinomial
h**l
发帖数: 4883
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
发帖数: 1791
8
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。
x*******i
发帖数: 1791
9
这个不难,用classical方法,做一个link function 就可以了。
h**l
发帖数: 4883
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。

相关主题
求助:Power analysis for poisson regression?请问poisson regression和 Log-linear model之间的联系?
一道概率问题.need help SAS Macro
在sas 里面,poisson regression model里面,response variable可以是binary吗?请教个问题
n*******m
发帖数: 101
11
how about poisson for rate?
n*******m
发帖数: 101
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
发帖数: 4883
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
发帖数: 242
14
我想你是不是可以用POISSON模型,但用不同的OFFSET(parameter is not just lamda
but lamd/offset)。 Y/OUTCOME就是错误的次数,OFFSET 就是总共经历过的测试。打
个比方,Y=5, OFFSET=5=>5次测试内发生5次错误的概率; Y=5, OFFSET=10=>10次测试
内发生5次错误的概率;Y=1, OFFSET=12=>12次测试内发生1次错误的概率。
n*******m
发帖数: 101
15
樓上正解。log(mu_i/t_i)=X*beta->mu_i=t_i*exp(X*beta),把t_i帶入就行了。
x*******i
发帖数: 1791
16
没明白为什么是5-12之间的数? 1-4为什么不行?说中文吧。说实话就没明白你想干啥。
multinomial 和binomial一回事。
1 (共1页)
相关主题
Gamma distribution for power analysis,请大拿指点a question about proc genmod
How to test a sample is negative binomial distribution求助:Power analysis for poisson regression?
model fit的疑难杂症: negative binomial regression 求指点一道概率问题.
请教logistic regression问题在sas 里面,poisson regression model里面,response variable可以是binary吗?
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?
怎么在sas中计算sensitivity,关于genmod?need help SAS Macro
怎么去读proc genmod的output(关于multinomial)请教个问题
请问怎么建立变量全是ordinal data的model?急,谢谢。multinomial distribution: how to derive the covariance of different variable
相关话题的讨论汇总
话题: binomial话题: poisson话题: students话题: tests话题: multinomial