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Questions tagged [fishers-exact-test]

A hypothesis test for contingency tables.

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Variation in the total number of samples when performing multiple fisher exact tests

I have dataset of 2 time points. In each time point I have to compare the counts of different components at each position (number of positions =1000). I used fisher exact test to compare if there is a ...
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1 vote
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Looking for a statistical test for significance of association between a treatment and non-mutually exclusive categories

I am looking for a statistical test which will give a p value for the association between a treatment and two potentially co-occurring labels: I have two categories of cells: state A and state B. A ...
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Equivalent of one-tailed Fisher's exact test for enrichment of the diagonal in 3x3 contingency table?

I have 2 ordinal variables A and B with 3 levels each (e.g. "down", "no change", and "up"). I want to know whether the up/down changes indicated by A and B are consistent ...
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How to express the uncertainty in the OR of a right-tailed Fisher's exact test?

Many OR (odds ratio) visualizations show 95% confidence intervals expressing uncertainty like on the left panel in figure below. However, in genomic overrepresentation analysis right tailed Fisher ...
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Can using Fisherian inference help me to be more confident of an underpowered result?

I am running a discontinuous regression to see the effect of a cash transfer on an outcome using a poverty index as the running variable. The problem is that the score is not a very good predictor of ...
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Fisher exact test in correlated dataset

Suppose I have n subjects. I have measured them twice with some binary outcomes. Now I want to test whether outcomes measured earlier agree with outcome measured later. Usually, I would need to do ...
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fishers exact test and chi-square test [duplicate]

What are potential advantages of chi-square test of independence over fisher's exact test? Alternatively, does fisher's have limitations?
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Fisher's exact test - how to find tables "as extreme"

I attempted to understand the computation of the Fisher's exact test through programming using this formulation: The Fisher exact test computes the p-values by finding the probabilities of all ...
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How to test whether the "prevalence ratio" of one marker is higher than that of another

Here is my setup. I have two sets of DNA sequences, one bound by a protein (transcription factor), another not bound by the protein. Let's say I have two candidate motifs, or DNA patterns the protein ...
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Analogue of fisher's exact test for one group?

I understand that Fisher's exact test applies to testing whether the proportion of an outcome in one group, $p_1$, differs from the proportion of the outcome in another group, $p_2$. This could be ...
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multiple testing adjustment for fisher exact test

I have 4 groups (G1, G2, G3, G4) consisting of samples of biological material, and we test them in order to identify are there any bacteria present. We also know that all of the samples contain virus ...
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How to account for population stratification in Fisher test?

When performing a logistic regression this can be done by adding covariates. How could I do the same for a Fisher test?
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Fisher's exact test when a category has a 0

I've been doing the univariate analysis for a retrospective cohorts study. In this variable in particular, none of the no-cured patients had a growth of grampositive bacteria in their culture. Since ...
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Can Fishers test of proportion be non significant by p value and be signficant by logistic regression

The proportion in one arm achieving an outcome is 101 out of 1152 The proportion in a second arm achieving an outcome is 123 out of 1155 Baseline variables predicting this outcome are available as ...
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Is there alternative to Fisher's Exact Test for 6X2 contingency table with the hypothesis of "less than"?

I have a table of contingency which is 6X2 and in my case, it is not an option to "convert" it in a 2X2 table. Also, I need to be able to use the hypothesis of "less than" and &...
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Checking expected counts when analyzing binary outcome and binary explanatory variable using GLM

Understand that chi-squared test comparing two categorical variables is only valid when expected counts for each cell is at least 5. I have not read or heard that this needs to be checked when running ...
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Fisher's exact test vs. differential gene expression

I identified SNPs that are associated with phenotype through GWAS. I labeled the types of genetic variants in those significantly associated SNPs and now I'm trying to assess the association of those ...
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Interpreting Fisher's exact test OR, CI and p-values

In the context of Fisher's exact test results, it seems that a bunch of online tutorials mainly focus on interpreting the p-value exclusively, without considering the confidence intervals or the odds ...
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Performing a Fisher test when the odds of the events not occurring are known to be very low when compared to the events occurring

Let's say I have a contingency table like this: ...
Caterina's user avatar
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1 answer
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Chi Square Test for inequal proportions of the categorical variable

I am testing relationship between gender and perceived cause of suicide in a group. So I wanted to do a crosstab in SPSS Gender(Male/ Female) vs Family Neglect (Yes/ No). However, the number of males ...
Dev's user avatar
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Statistical analysis of academic grades

Let's say I have 2 sets of grades from students. Maybe I'm looking at gender differences or some such but the disaggregating factor could be continuous or multinomial. Group A: 3 D's, 5 C's, 13 B's ...
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Is Fisher's exact test good for this use?

I have a table that looks something like this: group 1 group 2 group 3 group 4 region1 50 217 340 53 region2 32 23 36 42 :------- :-------: :-------: :-------: -------: male 40 200 36 42 female ...
anni's user avatar
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3 answers
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Is Fisher's exact the right statistical analysis to be using?

I am conducting a service evaluation study and want to assess the association between referral type (self vs. clinician) and gender (Female v Male v Other). Therefore my contingency table is 2x3. I ...
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Do I need to use Bonferroni correction in commutation study?

I have a table like this: ...
Caterina's user avatar
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What is the principle behind R's fisher.test for calculating odds ratio, p-value, and the 95% CI?Why is the manually calculated OR different? [duplicate]

There is a 2×2 matrix The manully calculated OR is 25, however, it is different from the odds ratio calculated by the fisher.test function in R,what is the principle behind R's fisher.test for ...
Arina Yang's user avatar
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Best test to compare cell population counts across patient groups

Given a data frame structure similar to the following: ...
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Infinite upper confidence interval using Fisher exact test in R

I am having trouble interpreting the upper confidence interval for the odds ratio (OR) after executing Fisher's exact test in R. I have the following contingency table which contains the response ...
Samuel Leal's user avatar
1 vote
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What post hoc test to use following Fisher's exact test?

I performed Fisher's exact test on a 4*2 table in SPSS, and I got a significant difference (P= 0.010) and I wonder what is the post hoc test to use following that? Is it the adjusted standardized ...
katib sareeh's user avatar
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Actual probability in Fisher Exact test

this is my code to calculate the pvalue of the fisher test for each pair of successes from two binomial distributions (n=m=20). Number of successes from 0 to 20 so 21x21 possible combinations. In ...
Bibi's user avatar
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How to generate significant level for the following data (Fisher exact)

I have a categorical data that I don't know how to generate the significant level. Row = Group A and Group B; Column = Unchanged, upgrade, downgrade (From left to right) 7 6 4 4 0 6 I tried to run ...
Ivan Leung's user avatar
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2 answers
135 views

What test can I use for contingency table bigger than 2x2 when some levels are n <5?

I've been trying my luck with my data, consisting in 2 vectors of 3 levels each. I got a 3x3 contingency table, and the details of the code (in R) I've used are in this question https://stackoverflow....
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Sub-sampling categories for fisher's exact test

Can I sub-sample categories before running Fisher's exact test? I have a 50 x 22 data matrix (50 categories and 22 samples), where some sample values are < 5, so I can't run a Chi Squared test. I ...
user81371's user avatar
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Fisher exact test for enrichment of subpopulations in single cell data

We have single cell data from 12 control and 12 diseased individuals. The data has been integrated (remove batch effects) and clustered. We would like to know if there are any clusters that are ...
decapicone's user avatar
2 votes
1 answer
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Null hypothesis significance testing when values are known

I'm looking at the association between two categorical variables in a genus of birds. The variables are 'Conservation Concern' (Yes/No) and another binary variable (Yes/No) and I have these for every ...
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Compare two proportions with a Bayesian analysis

I'm conducting an experiment in which participants receive either an object A or an object B. Next, we ask participants if they want to trade their objects with the alternative object (i.e., object B ...
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Comparing two proportions within contingency table for small sample size [duplicate]

I need some help for a statistical analysis. I have the following contingency table : I would like to compare p3 and p2, that is the comparing the proportion of event in G2 and the proportion of not-...
user381165's user avatar
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171 views

How to run Fisher's Exact test (in R) with multiple levels?

I have a data set that is separated by Stimulus Type, Sex, and Observed/Expected. I have many stimulus types (more than 100), and want to run a Fisher's Exact test on EACH to see if there is a ...
michellemoyah's user avatar
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Fisher's Exact Test Post-Hoc for 3x2 Table

I am running a Fisher's exact test on SPSS. There are 2 variables - 3 groups and their Pass/Fail frequencies: Group 1: 8 pass, 18 fail Group 2: 1 pass, 10 fail Group 3: 11 pass, 6 fail I am using ...
Statsyy 's user avatar
7 votes
1 answer
722 views

Interpreting zero odds ratio from Fisher's exact test

I did fisher's exact test and I got an odds ratio equal to zero. Can you please clarify what it means? I want to plot the odds ratio but don't know how to deal with the zero and INF values. below are ...
Marwah Al-kaabi's user avatar
1 vote
1 answer
169 views

What will happen to my results if I use Fisher's exact test with unfixed marginal totals?

I've been trying to get my head around the controversy that surrounds Fisher's exact test. I often use the test in the something like the following way: A survey asks respondents two questions: "...
David Lovell's user avatar
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268 views

Alternatives to logistic regression if there are zero counts

I have three variables (let's call them $A$, class (both binary) and age (numerical)), and I want to test if there is a difference in the presence of A between the two classes, with age as a potential ...
user36196's user avatar
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Is the Two-Proportions Z-Test the correct test to use when trying to compare specific proportions?

Hi supposed I have a table like this. ...
Ahdee's user avatar
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1 vote
1 answer
575 views

Fisher test: odds ratio greater than 1 and p-value greater than 0.05

Is it possible that in the output of fisher.test() in R p-value is grater than 0.05 and odds ratio is not equal to 1? I have this table. The output of fisher.test() is: P-value=0.1789 indicates no ...
Stella's user avatar
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Sample size required for Fisher's exact test

I am trying to determine the sample size I need to for 80% power at 0.05 significance in a Fisher's exact test. I want to determine if there is an association between colour and group (null hypothesis ...
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How can we have multiple "exact" tests?

Looking over the differences between Fisher's exact test and Barnard's test, it seems I'm missing something fundamental. If both are exact tests, shouldn't both give the exact and identical value for $...
Nathaniel Bubis's user avatar
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2 answers
501 views

What are the expected values in Fisher's exact test?

For me one of the most useful outputs from a chi-squared is the expected values. But in R, the expected values in a Fisher's exact test are not provided. What are the expected values in a Fisher's ...
luciano's user avatar
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1 vote
1 answer
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Fisher's exact test in survival analysis

How to do Fisher's exact test in univariate survival comparison on 2 groups (10 vs 15 patients), small size events ( 5 vs 3) and multiple times to events?
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2 votes
2 answers
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Survival analysis on small sample : Chi-square test or Fisher's exact test?

I'm running a survival analysis on a sample of 26 patients, divided into 2 groups according to certain variables and different times ( because there is censored data). I couldn't perform the log-rank ...
Soffee's user avatar
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1 vote
1 answer
465 views

Chi-square test for two vectors with very similar values

I have two vectors with two levels: vector 1:...
HAOYANG MI's user avatar
2 votes
1 answer
175 views

How do I calculate the uncertainty in process which estimates binomial distributions and has its own error rate

We have a series of binomial distributions, each with separate and distinct chance of success k. For some small subset of these distributions we have an absolute measure of k from the full population. ...
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