# Thread: looking for a relationship between multiple catagorical data sets

1. ## looking for a relationship between multiple catagorical data sets

I have recently come across a problem that is clearly out of my level of background, so perhap someone can help:

I wish to determine if condition 1 is related to conditions 2,3,4 etc. its not clear to me just yet how many conditions will ultimately be involved. I would like to get a sense of how to treat this. for each condition the is either a true or false outcome.

let me give an example that may help: I wish to know if the proportion of instances of condition 1 being present is greater or lesser when condition 2 is also present, then if it is greater when cond 3 is present and so on. now that part i can handle. but i would also like to know if the proportion of cond 1 is greater when both conditions 2 and 3 are true, or both cond 3 and 4, or both 2 and 4, or even if three conditions are present (ie cond's 2, 3 and 5).

I would think this has been done often, i just need a push in the right direction.

cheers
jerry

2. Hi Jerry,
Could you just explain more on conditions? and I guess it is a multinomial variable.

Richie

3. Hey Richie,

let me try an example:

suppose that for a subject we know that condition a is true, b is false, c is true, d is true, (all the conditions are binomial, eg true or false)

now we collect the same data on many subjects so that we find the proportion with a is .2, with b is .1 with c is .4 with d is .1; now i would like to be able to establish if a subject is more likely to have condition a be true if they have condition c true? or b true, or d true, etc.

another way of thinking?? maybe we want to test Ho: the proportion with "a" and "b" is the same as the proportion with "a" for all combinations of "a" and one, or two or more conditions.

thanks
jerry

4. this is not a multinomial variable, BTW

I am really trying to test wether there is a relationship between multiple binomial variables.

thanks again
jerry

5. I guess pairwise we can establish the relationship.
Suppose there is only a & b. In that case we can summarize the data into 2*2 table ( a=true b= true , a=false b = true , ... )
Then we can test both McNemar's paired test & chi-square test( independence).

6. I found a fellow to assist with this, I'll let you know what we come up with.
jerry

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