Hi there!

New user here, I hope I'm posting in the right section!

I was having some issues trying to figure out if/how I can apply a chi-square test to my problem.

I know how to deal with and interpret a case where I have only 2 mutually excluding groups, like male/female, and I want to determine whether a certain disease is more common in one of the groups. The null hypotheses is that there's no difference in the distribution of the disease between males and females.

I can organize the data this way:

and, after using a chi-square test, I can reject the null hypothesis, since I get a chi2 (11.686) higher than the critical value (3.841) for a significance of 0.05.

However, I'm trying to figure out how to deal with a situation where I have patients with multiple symptoms, so something like:

I don't think performing a chi2 test on the whole table as it is would make sense, right?

I was thinking I could treat them separately. For each symptom, I could create a single contingency table, considering the patients with the current symptom as a first category, and grouping together all the other ones not presenting the current symptom in a second category...so, something like:

and then perform chi2 tests on each table, to evaluate how much each symptom is an indicator of the presence of the disease.

But again, I don't know if it would be a correct approach.

Any suggestions about it, please?

EDIT: sorry for the formatting, I'm trying to figure out how to create these tables in a more readable way!

New user here, I hope I'm posting in the right section!

I was having some issues trying to figure out if/how I can apply a chi-square test to my problem.

I know how to deal with and interpret a case where I have only 2 mutually excluding groups, like male/female, and I want to determine whether a certain disease is more common in one of the groups. The null hypotheses is that there's no difference in the distribution of the disease between males and females.

I can organize the data this way:

Code:

```
| disease no_disease
-----------------------------------
male | 25 6
female | 8 15
```

However, I'm trying to figure out how to deal with a situation where I have patients with multiple symptoms, so something like:

Code:

```
| disease no_disease | TOT
-----------------------------------------------------------
symptom 01 | 20 20 | 40
symptom 02 | 10 5 | 15
symptom 03 | 10 15 | 25
symptom 04 | 10 5 | 15
-----------------------------------------------------------
TOT 50 45 | 95
```

**, and I'd like to figure out which ones are better indicators of the presence of the disease, but I'm not sure about how to approach the problem.***the symptoms are mutually exclusive*I don't think performing a chi2 test on the whole table as it is would make sense, right?

I was thinking I could treat them separately. For each symptom, I could create a single contingency table, considering the patients with the current symptom as a first category, and grouping together all the other ones not presenting the current symptom in a second category...so, something like:

Code:

```
| disease no_disease | TOT
----------------------------------------------------------
symptom 01 | 20 20 | 40
no sympt 01 | 30 25 | 55
----------------------------------------------------------
TOT 50 45 | 95
| disease no_disease | TOT
----------------------------------------------------------
symptom 02 | 10 5 | 40
no sympt 02 | 40 40 | 55
----------------------------------------------------------
TOT 50 45 | 95
| disease no_disease | TOT
----------------------------------------------------------
symptom 03 | 10 15 | 40
no sympt 03 | 40 30 | 55
----------------------------------------------------------
TOT 50 45 | 95
| disease no_disease | TOT
----------------------------------------------------------
symptom 04 | 10 5 | 40
no sympt 04 | 40 40 | 55
----------------------------------------------------------
TOT 50 45 | 95
```

But again, I don't know if it would be a correct approach.

Any suggestions about it, please?

EDIT: sorry for the formatting, I'm trying to figure out how to create these tables in a more readable way!

Last edited: