# Questions tagged [fishers-exact-test]

A hypothesis test for contingency tables.

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34 views

### Fisher's test and difference between observed and expected frequencies

I was trying to make sense of a statement I came across in a paper. The author states that "The difference between the observed frequency of zero and the expected frequency can now be tested for ...
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### Row wise Fisher's Exact Test and Multiple Comparasions Corrections

I am diving into different questions regarding multiple comparisons in Fisher's exact test to understand if I need correct my p-values in a row-wise post hoc analysis. The dataset has the group's ...
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### interpretation of odds ratio in fisher test for different cells in 2*2 table

I have the following contingency table: I used the Scipy library to compute the fisher_exact test and get the odd ratio. My p-value is 0.018 and the odd ratio is 1.32. I want to make sure about my ...
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### If in the Fisher's exact test, one did not condition on the margin totals, how would the margin totals be factored in the calulation?

It states in the following post What does the assumption of the Fisher test that "The row and column totals should be fixed" mean? that: Fisher's exact test conditions on the margin totals, ...
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### What is the implication of conditioning on the margins in the Fisher's Exact Test? [duplicate]

In the following post: Chi-square test or Fisher's Exact test, it was mentioned by Glen_b that You don't have to have fixed margins to use the Fisher exact test, you only need to be willing to ...
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### How to run a post-hoc correction test on multiple chi-square test?

I have run chi-square tests on occurrence of species across two time periods. As I have 1300 species I analysed them in bulk using a multiple loop function in R: chitest1<- t(sapply(seq(nrow(...
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### Does Fisher's exact test give any answers about proportions?

I have a table that looks like this: initial final fsa_top hours_top fsa_bot hours_bot 2020-01 2020-06 1540.33 35222.21 984.5 28765.22 2020-02 2020-07 1765.43 36782.99 976.22 27666.07 and so on I ...
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### Consistence between: binomial confidence intervals, fisher test and power? [duplicate]

The Question is at the end of the reasoning. 1 : Representation of binomial confidence intervals: We want to know if the proportion of reds in zone 1 is significantly different from the proportion of ...
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### What is correct way to calculate the expected overlap of protein sets in two related biological system

I have a question regarding the statistics of protein set differences in two biological samples. I have performed quantitative proteomics analyses on both WT and KO cells (derived from the WT cells by ...
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1 vote
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### How do I approach calculating an optimal sample size for injecting mice for triggering an immune response?

Hypothetical: there is a research team tasked with injecting mice aimed at triggering a specific immune response to produce monoclonal antibodies (MAb). Up until now, they've been largely unsuccessful ...
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1 vote
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### How can I statistically assess directionality for larger tables of count data (eg 2x3, 2x4)?

I have an experiment with 2 dependent variables (each binary decisions) that makes some quite distinct hypothesis about the manipulation. As there are 2 dependent variables, there are 4 outcomes that ...
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### Should I use Chi-Squared or Fisher's test?

everyone. I have a question which involves statistics and the R programming language, thus I believe that this question pertains to this forum, but if any of you know someplace else where I could go ...
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### Chi-squared or Fisher's or something else?

I am trying to see if there is a difference between two groups of turtles (adults and juveniles) and the location that they feed ('sea-floor', 'pelagic' or 'at the surface'). So the IV is 'life stage ...
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### Problems with in Fisher exact test: results by fisher.test and oddratio function of epitools package

This is my data mydata <- matrix(c(86,1,14,0), nrow = 2, ncol = 2, byrow = TRUE) When using fisher.test in R give ...
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### Fisher's exact test on k-mers counting - Bioinformatics

I'm quite new to the bioinformatics field, so I hope I won't make a too stupid question. I'm trying to compare different samples by applying some statistical tests (i.e. Fisher's exact test) to the ...
1 vote
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### Should I correct odds ratios for multiple testing and if yes, how?

I did I fisher test (2x3 table) and after a significant result I performed three separate fisher tests for the possible comparisions. I corrected the p-values for multiple comparisons, but in addition ...
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### Conditional Independence Testing using Fisher

I would like to prove the conditional independence of two categorical variables ("a","b") given a third categorical variable "z". I need some help in explaining the ...
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### Which statistic test/model is applicable?

I am currently working with medical data. I have created patient subsets if they fit certain characteristics, e.g. male & heigh >= 5 ft, female & height <= 6ft, etc...I am then comparing ...
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### Estimation of the equivalence between 2 populations by using a Fisher's exact test

I am currently working on an article about a genetic disease caused by 3 groups of genetic mutation. A group of genetic mutation is particularly much more serious than the 2 others. In this article ...
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### What test to compare two frequencies?

In my project I have to study the vigilance behaviour of birds, and I need to determine if adults start escaping from an approaching human more often than chicks. So I have the frequencies of adults ...
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### Selecting a test to prove that the observed changes in the performance of two machine learning models are statistically significant

I have developed two machine learning models which I evaluated with two different datasets. My initial hypothesis was that their performance would be higher in dataset 2 as compared to dataset 1. ...
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### Fisher's Exact Test for 4 subgroups

I have a question for using Fisher's exact test for subgroups. I have 39 subjects that was divided into 4 groups( n = 9, 5, 10, 15, respectively). There were 3 conditions dividing the groups. Table ...
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### Pvalue comparison at group or level

I am looking at pvalue. 2 groups x 4 levels. I ran a fishers exact test and got a pvalue. Does that pvalue relate to the group comparison as a whole or to a comparison of each individual level? Can I ...
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### Choosing statistical test for Preference-shift

I am having trouble choosing the proper method to support my hypothesis. I have conducted an animal study, where subjects chose A or B, 6 times a day for 3 days (day 1~3). At first, I divided the ...
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### Binomial test with Chance level prediction

Thanks for reading. I wanted to ask if my logic I used for my experiment makes any sense. My hypothesis is that watching Pepsi commercial increases Pepsi preference. My experiment has 2 steps. (1) ...
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### How to test if watching a advertisement only 1 time is enough to change one's preference

I'm sort of having a trouble finding what statistical test to use in a specific project of mine. My experiment was as follows: I have 10 friends and they all prefer Coke cola then Pepsi. Each of them ...
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### Hypothesis testing for ordinal proportions for multiple independent subjects divided between two groups

I have two biological groups - each with multiple subjects (7 in one and 10 in another). Each subject provides 40-80 observations, which can be classified into either of two ordinal categories. I have ...
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### Using svychisq with complex survey tables that have one or more cells with null values

Does anyone more experienced with R's survey package know about an alternative for svychisq for the case of a contingency table with at least one cell with a zero value? There does not seem to exist ...
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### Multinomial with small counts and many cells

I have data distributed as multinomial, with $N= 1,000$ observations divided among $n=10,000$ cells, with unequal probabilities $p_i$, for $i=1,...,n$. I would like to assess how likely it is that an ...
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### Fisher's exact test with altered null hypothesis/expected frequencies

I'm trying to determine whether or not exposure to extreme temperatures after hospital discharge affects the chance that a surgical patient will be readmitted. An extreme heat exposure is defined as a ...
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### Testing the difference of proportions equal to a certain value

Suppose there are two samples $X_1\dots X_n$, $Y_1\dots Y_m$ of binary variables $X\sim Bern(p_1)$ and $Y\sim Bern(p_2)$. Is there any way to test the following hypothesis by the exact test? H_0: ...
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### When to correct for multiple comparisons when using fisher exact test?

Please, I'm just confused about whether to use a correction of multiple comparisons of the p values that I got from fisher exact test or not?. The data that I have is something like this: ...
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### The use of Fisher's Exact test for Cougar (Puma concolor) Injury in the United States

In 2019 a research paper was published measuring the association between cougar attacks on humans using the Fisher's Exact test between 1924 to 2018 . There were a total of 74 attacks reported from ...
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### Careful comparison of strength of evidence (p-values)

Please hear me out before you roll your eyes when reading about "p-value comparisons". I have the following scenario: High-dimensional, clustered data and two groups within each cluster. ...
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### Do poisson regression and exact poisson regression only differ in confidence interval?

The point estimates from the two approaches are the same, right? I plan to use exact Poisson regression for a study, since the events could be sparse after adjusting for a few covariates. Is there ...
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### Test for statistical significance between groups in categorical count data with multiple samples

There are two groups/genotypes of mice (WT, KO). For each genotype, four mice were separately used to determine the identities of thousands of individual cells from a particular organ, assigning them ...
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### Fisher's exact test in more than 2 variables

I have some data with three independent categorical variables (one has a sense of order, the others do not) and one dependent categorical variable. Is there an analogue to Fisher's exact test where I ...
1 vote
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### Hypothesis testing: Fisher's exact test and Binomial test

My first post in this community. My knowledge of statistics is limited, and so I am seeking advice on the following problem. (Sorry for the long post, and thank you in advance for your help). I have a ...
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### Significance Testing for the Difference between Binomials [duplicate]

I have two algorithms, $A_1$ and $A_2$. $A_1$ either accepts or rejects samples from dataset $P$ $A_2$ either accepts or rejects samples from dataset $Q$ Below is a 2x2 contingency table for the ...
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### Compute p-value in a contingency table other than 2x2 table

I guess I have a newby question here. I have used the tableone R package to create the contingency table shown below. I am struggling to understand which test was used by the package to compute the p-...
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### Interpretation of Odds Ratio (OR) in Fisher's exact test [duplicate]

I've tried using R operating Fisher's exact test to test for independence of the 2 datasets below and struggling to interpret the Fisher report. Please have a look at the data and the Fisher's test ...
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### Interpretation of Odds Ratio (OR) in Fisher's exact test

I've tried using R operating Fisher's exact test to test for independence of the 2 datasets below and struggling to interpret the Fisher report. Please have a look at the data and the Fisher's test ...
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1 vote
475 views

### Fisher Exact test - Can't replicate SPSS results in Excel

I've been doing some Fisher Exact tests in SPSS and am trying to do in Excel instead. So i can do automatically for rows of data. But I can't get the Excel results to match the results from SPSS. The ...
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### Percent chance that two samples are different population (NPS)

Practical question (not a statistician), I want to make a PPT slide (amongst several) in a business discussion, related to comparing a new survey with an old one. Want to be able to say something to ...
1 vote