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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75 views

I don't understand Chi squared

I think of the contingency table test. In all textbooks I've seen, the test statistic is calculated as the sum of $(O-E)^2/E$ over all cells. But the degree of freedom is not the number of all cells. ...
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32 views

How important is the arrangement of data in a 2x2 contingency table for fishers exact test?

I am comparing expression of different genes involved in the same metabolic reaction of basil to two different conditions, exposure to cold Vs Infra-red light. I am in the process of analysing RNA seq ...
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1answer
33 views

Is it possible to compute the mean/median of an variable by a contingency table?

A contingency table contains the frequencies of two discretized variables. To be more specific, the discretization is done by splitting the spectrum of a signal into equal width intervals. Is it then ...
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1answer
40 views

Using contingency tables for testing multiple dependencies

I know that I can determine the correlation / association / dependency between two variables (X= smoker, and Y=cancer) using chi-squared with a 2x2 contingency table: ...
2
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1answer
39 views

Help with analyzing/planning a physical experiment — regression

This is a real experiment about to be performed Batches of samples will be prepared. A Striker will be used to see if a reaction will occur. For example: 20 drops might be performed, and number of ...
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0answers
21 views

Test for independence in 3x2x2 table with small expected cell values

I have three unordered categorical variables. I have made a 3x2x2 table, but I'm uncertain of how to test for independence. The usual manner is a chi-squared statistic, but I think this is ...
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12 views

rxc contingency tables

Hi I am trying to analyse categorical data and to construct a contingency table based on a survey data. In the contingency table, there were 5 ordinal ratings(blank, unacceptable, below average, ...
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4
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1answer
239 views

Why does Pearson's chi-squared test detect differences that the GLM model fails to detect?

How can I interpret the following result? I have 4 groups with around 300 observations each: ...
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43 views

Disproportioned contingency table

I have a database of clients, some of which have gotten a special pill - and the rest have not gotten the special pill. Afterwards I measure if the clients starts exercising. My contingency table ...
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1answer
56 views

Contingency table for gene groups

I have two lists of genes as follows: DEList has 282 gene names AllList has 32805 gene names ...
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31 views

A generalized measure of relative enrichment for elements of a contingency table [closed]

Problem: If given a matrix of counts of observations between some features (F) f1-f4 (e.g., GO terms or pathways, in rows) and genes / proteins (P) p1-p3 (in columns), what would be: A good way to ...
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0answers
10 views

Help interpreting this result based on conditioning on gender -Contigency Tables

The problem i'm having is how to interpret the results I got. For part a) I got that the abortion laws are independent of generation where I used a $\chi^2$ test. For part b) I got that the the age ...
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7 views

Regression Model for Matched Continency Tables Coefficient Interpretation

Sorry to insist. A number of questions in the same direction (coefficient interpretation) by different contributors, never answered. ...
2
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1answer
26 views

Regression Model for Binary Matched or Paired Contingency Table Results

This is a follow-up question on a prior thread about the same setup as follows: We have two "Methods" ("A" and "B") to diagnose a medical condition. We are not trying to determine which one is better ...
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0answers
35 views

Fisher's exact test for 3x5 contingency table in R with post-hoc? Consistently with using Fisher or Chi-squared?

I'm struggling with some (relatively simple) stats questions for some work I'm doing in R, and can't seem to find answers online... I have a factorial response variable of habitat type of a species ...
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0answers
16 views

Correlated Proportions shown in a Mosaic Plot. What is the fitted model that generates residuals?

I have a 2-by-2 table of correlated proportions where I am plotting the positivity of two diagnostic methods applied on a sample of 216 individuals: ...
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0answers
44 views

Dimension reduction for discrete qualitative and aggregated variables

I know about PCA for multiple dimensions of continuous features but here is a problem I have some trouble to find a method for. I don't have a list of individual countries but rather a discrete ...
2
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0answers
23 views

Fisher's Exact Test for 2x3 tables

I'm writing my dissertation and I need to cite a source to support using the FET for 2x3 tables. Does anyone knows of a source that can be cited? Thank you!
2
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1answer
36 views

Is this a valid use of “positive predictive value”?

So here's your typical table for evaluating the performance of a diagnostic test: Gold standard result ...
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24 views

Calculating Odds Ratios for a 3 x 3 Table

How would I go about calculating the Odds Ratios (measures of association) for a 3 x 3 Table
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2answers
127 views

Is the chi-squared test appropriate with many small counts in a 5x2 table?

I have two sample populations, A, and B, which are independent. ...
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0answers
86 views

SPSS chi-square output interpretation

Sorry for the dumb question, I need some help with the interpretation of the spss chi-square test outcome. Basically I have two variables: the first one is a binary variable which takes value 1 if a ...
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2answers
162 views

How to simulate effectiveness of treatment in R?

Let's say I want to write a simulation for the table below to decide if Xylitol treatment and ear infections are independent. How would I go about doing this?
2
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1answer
38 views

chi-squared / Fisher's exact test with incomplete data for contingency table

I have a treatment group (n=42) and a control group (N=12). From this this, 13 used in the treatment HTN drugs and 4 people in control group used HTN drugs. How should the contingency table be set ...
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34 views

Test of Independence Between Two Nominal Variables With Many Levels Each

I am looking to test whether there is a significant relationship between two nominal variables, one which has 100 levels and the other with 10 levels. I initially considered doing a $\chi^2$ test of ...
2
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1answer
135 views

Computing the power of Fisher's exact test in R

Suppose that I have the following 3 x 3 contingency table: ...
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0answers
30 views

A question about the distribution of the log odds ratios in multivariate contingency tables

I know that in $2 \times 2$ tables, one may compute the standard error of the log odds ratio by the formula $$\sqrt{\frac{1}{N_{11}} +\frac{1}{N_{12}}+\frac{1}{N_{21}} +\frac{1}{N_{22}}}$$ where the ...
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1answer
299 views

how to compare two percentages to prove for statistical significance

I have problem to compare the two percentages and to get the statistical significance for these two different percentage. I just want to approve whether these two percentages are significant or not ...
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373 views

What distribution does Fisher's exact test assume?

In my work I have seen several uses of Fisher's exact test, and I was wondering how well it fits my data. Looking at several sources I understood how to calculate the statistic, but never saw a clear ...
3
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1answer
45 views

Denominator term in Chi-Square-Test for association in a contingency table

The general formula for the Chi Square Test for association in a contingency table with $I$ rows and $J$ columns, and cell counts $n_{ij}$ is $$ \chi^2 = \sum_{i=1}^I \sum_{j=1}^J \frac{(n_{ij} - ...
3
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52 views

chi-squared test vs fisher's test vs … => highly unbalanced length frequency data

I would like to statistically verify if two distributions are identical. Basically, the first distribution is a length frequency distribution from a large population ("population"). The second is the ...
2
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2answers
98 views

Chisquared on categorical data or a Wilcoxon test on the counts hereof?

This question is related to a question I had in R on SO here The background of my question is fairly simple. I was given two "databases" in the form of data.frames ...
0
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1answer
38 views

How to perform a conditional cross-tab in R or Excel? [closed]

I recently was given a project which consists of: pulling together words from ~500 small tweets and doing a matrix, which shows which words occur together in which tweets. I am wondering how I can ...
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2answers
89 views

Hypothesis testing using R

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1answer
25 views

Log Linear Models: Interpretation when None Fit

This is question 9.6 from Categorical Data Analysis by Alan Agresti (Wiley, 2013). The question asks us to find a Log Linear with the best fit for a 2x2x2 contingency table. The following are the ...
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0answers
6 views

How to adjust logistic models in case bivariate analyses encounter issues?

The model looks like: Y = X1 + X2 + ... + Xi Y is categorical or, to be exact, ordinal Xs can be categorical (dichotomous, ordinal, nominal) or continuous I first run bivariate analyses between Y ...
2
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0answers
35 views

Does N-1 correction for Pearson's Chi-Square apply to r x c tables generally?

Campbell (2007) recommended what he called the "N-1" correction for chi-square tests performed on two-by-two contingency tables. He described the correction as: "the K. Pearson chi-squared test ...
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0answers
49 views

How to enter data into contingency table directly?

I'd like to create a contingency table. I do it using: matr=matrix(c(62,61,36,19,10,21,58,60,39,22,12,19,91,83,72,23,52,62,43,28,59,57,29,20,12),5,5) but it ...
3
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1answer
133 views

Hypothesis testing based on Likert type data

I know this site is full of similar questions, but either their answers do not apply, or I'm missing something. I have data from a questionnaire. Responses are in the form of Likert items, some of ...
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0answers
51 views

Seeking basic advice re. contingency matrix for time-limited predictions

I am looking for advice on how to construct a contingency matrix ... A subject is measured on day 1 and a score is computed. This is repeated daily generating a series of scores. If on a given day ...
0
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0answers
44 views

Two tails or one tail McNemar's test in a binary classification problem. Which one should i choose?

I'm using McNemar's test for compare two designed models in a binary classification problem. As you know we have two kinds of this test. ...
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1answer
510 views

3x3 contingency table: what to use instead of chi-squared test?

I have questionnaire data from subjects divided into 3 groups, G1, G2 and G3. Subjects had to answer a question, and they had the options A1, A2 or A3 to choose from. The correct answer depended on ...
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0answers
20 views

test to show statsticial change due to an intervention

I have a group of 222 test results that were reviewed separately by two interpreters X and Y. Based on their assessment, they were to assign management into 4 categories A, B, C and D. Then another ...
2
votes
1answer
204 views

stats for 2x4 contingency table with both very large and small or zero counts

I have 7000 2x4 contingency tables with count data. They represent a particular position in a genome and the number of times each dna nucleotide is observed at that position in 2 different ...
2
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0answers
39 views

Visualise significant differences in a contingency table?

I'm working with pandas and scipy, and I would like to find a quick way to visualise unusual values in a contingency table. Say this is my contingency table: ...
0
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2answers
86 views

Logistic regression, Chi-square, and study design

I have a study in which I have developed a new predictor (binary) for a disease (also a binary variable). The study has two parts. In the first part, I want to test if my predictor is strongly ...
2
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0answers
143 views

2x2 contingency table - maximum likelihood estimate of the odds ratio and exact confidence intervals

I have two questions regarding the following 2x2 contingency table: 1, How can I derive the maximum likelihood estimate of the odds ratio ($OR = (a*d)/(c*b)$) 2, How can I derive exact confidence ...
2
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1answer
195 views

Proper analyses for 2x2 contingency tables

So I have multiple questions about the different types of analyses that can be used on a 2x2 contingency table and when different analyses should be used. To open, I'll note that this stems from my ...
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1answer
122 views

Why use chi-square (or other) statistic over regression modeling for 2x2 contingency tables?

I have a question regarding the use of logistic/log-linear regression vs. contingency test statistics, such as chi-square. Can someone explain to me why it would ever be preferable to use test ...