# Questions tagged [fishers-exact-test]

A hypothesis test for contingency tables.

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1answer
17 views

### Calculate sample size for Fisher Exact Test

I'm researching the role of sender reputation in remediating Android vulnerabilities using large-scale notification campaign. There are 2 senders with different reputations and 1 as a control (no ...
0answers
22 views

### Which Statistical Hypothesis Test is appropriate Here?

I have two contingency tables (screenshots below) - This is the results of age range 19-30, I also have two tables for above 30s. I am requesting help with rejecting a null hypothesis. The data was ...
0answers
12 views

### Fisher's Exact Test for 2x2 Table with Random Zero

I'm trying to determine if the rate of mutation for a particular gene is significantly different between two groups (primary tumor and metastases) with Fisher's exact test and so my contingency table ...
0answers
25 views

### fisher.exact test not returning expected p-value [duplicate]

I am trying to run Fisher Exact Test, however, I get unexpected results. I thought the two.sided p-value should be twice as large than the minimal one-sided p-value....
0answers
7 views

### Freeman Halton Long hand

I am looking at this site: https://www.danielsoper.com/statcalc/formulas.aspx?id=58 Where for a 2x3 table it gives the following formula: The calculator equivalent (https://www.danielsoper.com/...
1answer
9 views

### Freeman-halton simple examples?

Does anyone know where I can see a step by step simple example of the Fisher-Freeman-Halton equation? I am a developer so need to build the process from scratch and have already done so for the Fisher ...
0answers
6 views

### How to correctly merge two files and count values before Fisher's test in R? [migrated]

I am very new to R, so I apologise if this looks simple to someone. I try to to join two files and then perform a one-sided Fisher's exact test to determine if there is a greater burden of qualifying ...
1answer
20 views

### How is fishers exact test calculated for non mathematician

I am referring to the Wikipedia example here (https://en.wikipedia.org/wiki/Fisher%27s_exact_test) which shows: My Question is how is this 0.001346 figure reached? After reading, I appreciate that ...
0answers
17 views

### Boschloo or Barnard? In which case?

For 2x2 contingency tables, my understanding is that Boschloo and Barnard both have uniformly more power than Fisher's exact test (even if all marginals are fixed??). But I am still confused about the ...
0answers
20 views

### Fisher exact test manual input of observed and expected

I have a 4x4 table and I want to test if observed proportion equal to a given expected proportion I provide. Because the counts between observed and expected are very different, I am interested in ...
0answers
22 views

### Comparing multiple sample proportions between two groups where one group is a subset of the other

I have 2 populations which I want to test if the proportions between group A and B are the same for each location or not by using hypothesis testing. It's very much as this problem described here: ...
0answers
144 views

### p-value from fisher.test() does not match phyper() in R?

My question was inspired by this topic, but is a bit different: phyher() in R and Fisher exact test p-value I try to understand how does it work? The question is as follows: knowing that 50 people out ...
0answers
7 views

### Getting similar p values from test on count data, even when case control imbalance is large

I am testing association between a gene version (allele) and a group status (group 1 or group 2). If I run fisher exact test (FET) with not too imbalanced groups, I get P=0 ...
1answer
24 views

### How to use permutation test to find significant outcomes from many fisher exact tests

I am reading from this where they mention running 500K fisher exact test to find significant associations between different DNA changes and a phenotype. They also mention that Bonferroni, Benjamini, ...
2answers
37 views

### Chi Square Test on small sample size

I have the following dataset and I am trying to run a Chi-square test between the control and pilot. The only issue is that, for a Chi-Square test to return proper results, the sample size need to be ...
1answer
10 views

### Establish confidence / error for multiple contingency tables with dynamic outcomes

In a task, a participant sees two types of prompts, 1 and 2. The participant might answer A or B. The participant might give an answer that cannot be coded as A or B, we treat these as missing data. ...
1answer
34 views

### Use of Chi-Square test of independence / Fisher Exact Test?

One of my research hypotheses is that individuals from Southeast Asia who are ethnically Chinese are more likely to experience racially motivated hate crimes than their counterparts from other ethnic ...
0answers
20 views

### Interpreting post hoc multiple comparisons test?

I have a conducted a Fisher's exact test with Monte Carlo simulation which resulted in a significant p value. My row variable, which is the # of people, has 4 levels (0, 1-50, 51-100, 101-150) and my ...
1answer
86 views

### Post hoc test for Fisher's exact test (larger than 2x2)?

I have 2 categorical variables: Var1 - 3 levels, Var2- 5 levels (i.e., table is bigger than 2x2). I'm using SAS, and since I have multiple cells <5, I have run a Fisher's exact test with Monte ...
1answer
34 views

### Sample size for binary outcome with rare events

I want to compute the sample size to compare two groups for a binary outcome where we expect rare events. I will do an example with R. Assume the following expected probabilities of observing an event ...
1answer
97 views

### Comparing multiple sample proportions between two groups

Hi all and thanks for taking the time to read this question. I'll try to be as clear as possible! The data: I have one sample of patients which was divided in two groups based on a binary variable for ...
1answer
70 views

### Can the Fisher exact test be used to get a confidence interval for the efficiency of a vaccine (risk ratio or relative risk)?

Consider the Pfizer vaccine for COVID-19. The data from the phase 3 trials shows that they had 21720 people in the vaccinated group and 21728 people in the control group: ...
0answers
8 views

### How to compare patient groups in cohorts containing different distributions and subtypes?

I have performed targeted sequencing on a panel of genes resulting in variant data for a cohort consisting of patients with different cancer diagnoses. These same genes have been analyzed in other ...
1answer
22 views

### Are the sum values 'No' and 'Not informed' in the Odds Ratio analysis correct? See the example

In a hypothetical study I am trying to assess whether the presence of allergy is a risk factor for the presence of any virus. For this purpose, a questionnaire was applied on which many individuals ...
0answers
5 views

### Are the data grouped by different drug doses graded data or disordered data?

I have a set of data, the structure is as follows: 5mg 10mg 15mg 20mg Survive 15 22 18 24 death 3 2 3 2 I divided the patients into 4 ...
1answer
49 views

### For the confidence interval of median using the binomial distribution why is it called exact and how does it differ from the naive loop-based method?

When I searched across documentation of various statistical packages, I noticed that the confidence interval for median based on either the binomial or beta distribution is called exact. For example: <...
0answers
19 views

### Algorithm to compute p-value of Fisher's exact test based Monte Carlo (bootstrap) simulation

I am looking for code to compute the 1- and 2-sided p-value for Fisher's Exact test for 2x2 tables based on Monte Carlo (bootstrap simulations). For larger 2x2 crosstabulation tables, the exact p-...
1answer
31 views

### Fisher's Exact Test for many 2x2 data sets

I'm trying to find an appropriate test or method to determine if the presence of a binary condition causes a separate binary result, given lots of situations (data points) of the 2x2 input/output ...
1answer
53 views

### Is Pearson's chi-squared test of independence conditional on marginal distributions?

The Wikipedia page on Pearson's chi-squared test states that a difference to Fisher's exact test is that the latter makes the "assumption of fixed marginal distributions". I assume that ...
1answer
25 views

### How to interpret significant likelihood ratio and insignificant Chi-square tests?

To analyze frequencies in a 2x2 table, I ran a statistical test procedure using SPSS. It returned a p less than .05 for the likelihood Ratio but greater than .05 for Chi-Square and Fisher Exact Test (...
0answers
13 views

### Statistical test for comparison of counts for 2 groups where requirements for Chi-Square test are not met

I would like to compare overall codon counts in the yeast genome with codon counts from an individual sequence. The totals for the 2 groups are not the same. I cannot use a chi-square test, since when ...
3answers
835 views

### Analysis of Danish mask study data by Nassim Nicholas Taleb (binomial GLM with complete separation)

Recently, Nassim Nicholas Taleb made this post about the recent Danish mask study, a randomized controlled trial which concluded that the proportions of newly diagnosed coronavirus infections was not ...
0answers
28 views

### Comparing win loss records or test results for statistical difference

I was reviewing some game statistics of wins and losses and was wondering what is the best approach to differentiate between how likely a person or team who had come in first is statistically that ...
1answer
108 views

### Test if two averages of two binomial distributions are statistically significant to one another

First, this may be a duplicate of: statistical significance I'm unsure if that post covers my exact situation. If so, just mark this as a duplicate. Let's say I have a list of 100k potential clients ...
0answers
12 views

### Fisher's exact test on Frequency of Occurrence data

I am working with diet data of chicks from a single colony from multiple seasons. The data consists of actual counts and frequency of occurrence (%) of 4 prey groups from 8 seasons extracted from diet ...
0answers
313 views

### Help with a 2x3 contingency table significance test

MD here completely new to doing my own statistics In a study I'm currently working on, I have three groups that I am assessing for a various categorical Yes/No Variables, for example: Without ...
1answer
160 views

### Why is my Fisher's test “significant” but odds ratio overlaps 1?

Given a contingency table of the following rare event, why does my Fisher's exact test produce a "significant value" (i.e., < 0.05) but also show that the OR overlaps 1? My understanding ...
0answers
22 views

### outage frequency analysis

I have several outage data points. Each outage has a time category (TP1 - TP3 - one could argue this is an ordinal variable) and week day. The rolled up (artificial) frequencies data looks as follows: ...
0answers
53 views

### Random distribution which statistical method

After K-means, I am iterating over many files consists of tables, mostly are 3X3. Some of them with "0" elements inside cells but most of them aren't. I read that chi2_contingencycouldn't be ...
0answers
11 views

### Choice of covariate under Independent Hypothesis Weighting (IHW)

After reading this survey of methods for controlling FDR and considering my problem at hand (https://genomebiology.biomedcentral.com/articles/10.1186/s13059-019-1716-1), IHW seems like a good choice. ...
1answer
46 views

### Best method to analyse multiple 2x2 contingency tables of a small sample?

I already looked around quite a bit but didn't find answers (I understood), so I apologise if this question should be a duplicate. I'm analysing a small cohort (n=15) of people with some observed ...
1answer
117 views

### Connection between Bayesian A/B testing and Fisher's exact test (specific example on Hydroxychloroquine trials)

I understand that there are multiple comparisons floating around between Fisher's Exact Test and Bayesian A/B Testing, here's an example. While I do understand these are fundamentally making different ...
0answers
9 views

### how to perform Beta binomial distribution for the count category in R language

Dear friends I have a data-frame looking like this ...
0answers
58 views

### Power of Fisher test vs chi squared

Consider an $m \times n$ contingency table and test of independence. Suppose the expected counts are such that chi-squared test is not recommended (close to zero in some cells), as it becomes pretty ...
1answer
20 views

### Which test fits the best here? (oncogenic signalling pathways)

I have a list of patients in rows and oncogenic signalling pathways in columns of two independent matrices One for responders to a drug one for non-responders to the same drugs If a patient gets ...
0answers
52 views

### Chi squared test questions

As part of a small study, I've have put together a table with results from a population of individuals stratified by age. For each line, I would like to perform a comparison between a variable and the ...
1answer
193 views

### Why am I getting p=1 in Fisher's exact test?

I have 8 IV and 1 DV, they are all dichotomous and categorical data, so I am using Cross-tabulation Chi-square test. So 8 tests conducted. All test have at least one expected count less than 5. So I ...
2answers
360 views

### Comparing multiple distinct proportions between two groups

I have two groups (group 1: $n=100$, and group 2: $n=200$), and multiple proportions for each group (where the number represents the proportion of individuals in the group with each disease). Example: ...
1answer
73 views

### Does it have any meaning to compute the $\chi^2$ and the exact Fisher test on big contingency tables

I have several datasets containing integers. I want to perform a bivariate analysis between a specific subset of variables. However, some of them have a lot of modalities. Is computing a $\chi^2$ ...
1answer
34 views

### How to deal with zero cells in 2 x 2 tables, using R

I am trying to look at the relationship between two nominal variables, using R. However, I am not certain how to deal with cases where a 2 x 2 contingency table has one or more zero cells, as shown ...