# Tagged Questions

Tables of counts (occasionally proportions of marginal counts), arranged by (at least) two marginal categories, displaying bivariate or multivariate frequencies. Sometimes called crosstabs.

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### Test for paired data on categorical variable with >2 levels

I am looking for the appropriate statistical test to compare frequencies over a categorical variable with >2 classes, for paired data (in practice, each individual has been labelled A, B, C or D ...
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### Is multinomial logistic regression appropriate for a dataset containing categorical data with small cell counts?

I'm analysing a large dataset from a questionnaire with 560 respondents. A cluster analysis performed based on coded free-text data resulted in 11 mutually exclusive clusters. Based on explanatory ...
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### Test contingency table for independence, when sampling/data structure contains dependencies

Problem Assume we have the following raw data: ...
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### How to express cells of a 2x2 table in terms of phi coefficient and marginal probabilities

Consider a typical 2x2 table of frequencies (shown in this image): Notation: The row variable is denoted R and takes on values 0 or 1; the column variable is denoted C and takes on values 0 or 1. The ...
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### An appropriate alternative to chi2 for paired, categorical data (tables larger than 2X2)

I am analysing a data set consisting mostly of categorical data. This has resulted in a number of contingency tables (mostly, but not always larger than 2X2) that need statistical testing. Now, I ...
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### significant chi-squared test but confidence interval for odds ratio does include 1

I have the contingency table: A B a 28 0 b 35 9 I applied the chi-squared test with Yates's correction, with p-values: ...
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### why are the degrees of freedom for a chi-square test on a 2x2 contigency table always 1?

I know the "formula" is (# rows - 1) * (# columns -1). However, shouldn't the design of the experiment or observational study being conducted make a difference? The only experimental design I can ...
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### Preprocessing contingency table

I'm going to apply a correspondence analysis on some datas. I'm having doubts on preprocessing the contingency table: my dataset contains informations on salaries and problems in different spanish ...
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### Which observed frequency in a 2x2 contingency table is responsible for rejection of H0?

I'm carrying out a study on reported deaths of vultures (Gyps fulvus) in the Apennine mountains, Italy. I've performed a chi-square test on a 2x2 contingency table relating gender (male, female) to ...
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### Comparing set of counts with different n sample and many zeros.

I had a look of may treats and find different pieces here and there but I cant figure out how to do this "simple" comparison. I have 2 counts (obtained with different methods but assuming from same ...
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### Hypothesis testing for difference in proportions when pooled population proportion is known

The example I use below to frame my questions is a bit contrived, but I am hoping the answer will help to clarify my understanding of more complex, related issues. Suppose we know in advance that the ...
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### Chi square test in a contigency table with sampling zeroes

im trying to estimate if an association exists between two variables in a 7x5 contingency table (the type of prosthesis with the type of complication). The table contains a lot of sampling zeroes and ...
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### How to proceed with chi square test in R if one line has zeros?

I am trying to program with R. My categorical data is in a table of 5*5. However, the 5th line has only zeros. When I run the chi square test in a software program, it returns the result INVALID. But ...
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### Fisher and chi-squared assumptions/limitations not met

Fisher exact test is said to be used with a total sample (n) < 1000, whereas chi-squared test should be used when each category (/cell in a contingency table) >=5. What if you have an mxn ...
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### Effect size measure for mxn Fisher Exact Test

I'm using the R function to run fisher exact test for mxn contingency tables (since my sample size <5; limitation of the chi-squared test). Along with the p-value I want to state the effect size. ...
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### Fisher's exact test vs kappa analysis

I was reading a paper where the authors assessed the association between two different diagnostics tests intended to diagnose the same disease and they performed the analysis with Fisher's exact test. ...
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### How to test the independence of two categorical variables with repeated observations?

I'm wondering how to test whether male and female birds differed significantly on the preference of habitat type on the following contingency table. ...
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### Interpretation of global test (p-value) of the interaction term with two categorical variables, each has 3 levels, in Logistic regression

My data: I have a dichotomous outcome: Disease(Y/N); and 2 categorical independent variables, each has 3 levels -- IPV: 0 (ref), 1, 2 -- Race: White (ref), Black, Hispanic My research question: ...
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### Calculating degrees of freedom for a contingency table with interactions

Below is a contingency table with residual deviance given by a Poisson regression model with a log-link. I have searched online and I believe that for the mutually exclusive model ...
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### Logistic regression vs chi-square in a 2x2 and Ix2 (single factor - binary response) contingency tables?

I'm trying to understand the use of logistic regression in 2x2 and Ix2 contingency tables. For instance, using this as an example What is the difference between using chi-square test and using ...