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# Questions tagged [chi-squared-test]

A test (typically of distribution, independence, or goodness of fit), for the family of distributions use [chi-squared-distribution].

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16 views

### How use chi-squared test to assess differences betweens two years

I administered a questionnaire to assess employee knowledge levels in math and English for the years 2020 and 2021. The question asked were presented as follows: ...
1 vote
31 views

### Why shows a two variable $\chi^2$-test a significant p-value while a log linear analysis on the same data does not?

I did an experiment to look at the influence of two categorial variables onto a categorial output. The input variables were T and ...
10 views

### What test to do when comparing multiple proportions? If Chi-squared, how do I see where differences lie?

I have a sample of data in R looking at vendors and I would like to compare the % of vendors which sell a product for each vendor type, as in the table below: I have further data for which I want to ...
6 views

### Goodness of fit test, variable dice faces and count [closed]

In a roll-playing board game, there are various kinds of dice. Dice may have 4, 6, 8, 10 or 12 sides. On any throw, we may toss 1-5 dice of the same kind. Dice are fair. Given a sample of 100 throws, ...
1 vote
38 views

### Test of good fitting on a sigmoid [closed]

as you can see on the figure i linked i am currently fitting my data (which looks like a sigmoid) using a function i defined with 5 parameters. ...
22 views

### How to perform a proportion test comparing noise proportions in different groups?

I have a dataset containing observations of wave lengths in milliseconds and the corresponding durations of noise in milliseconds. Each observation is labeled with a group (A or B) and a subject. I ...
11 views

### Issues with generating Odds ratio in R [closed]

why am I getting the error message that my R could not find the function odd ratio? although I have used them recently.
1k views

### References on how to interpret significant but dubious results (i.e. small numbers, plus borderline p-value)

I'm comparing two groups of people on a binary variable. The number of successes is really small for the two groups (which wasn't expected, due to a lack of previous quantitative research on the ...
273 views

### Obtaining the chi-squared test statistic via geometry

I’m trying to informally derive the chi-squared test statistic using a combination of basic geometry and algebra. I’m successfully able to obtain a system of equations that contain Karl Pearson’s chi-...
27 views

### Chi2 or Kruskal Wallis?

I have 3 different groups based on their level of resilience : low (n=60), moderate (n=35), high (n=10). After a qualitative thematic analysis of their responses, different subjects emerged, like &...
9 views

### Contrast for hourly counts between 4 groups

I am studying the incidence of different types of stroke in a hospital. I have the information about the time of arrival of each patient and the type of stroke. I divided the whole day into 6 time ...
34 views

### Question about using the chi-square test on an astronaut dataset to determine if over 1000 hours in space and early mortality are related

I am analyzing an astronaut dataset to try and determine if a high number of hours flown in space (>1000) by an astronaut is related to premature death (which I defined as dying before the age of ...
9 views

### Survival, Descriptive, and Group Comparisons (>2 groups)

I am performing a survival analysis with three cohorts. In the descriptive analysis, I have used Fisher and chi-squared tests to compare the categorical variables (such as sex), and the Kruskal-Wallis ...
16 views

### Chi-square: correlation or comparison test?

I find some references and discussion state that Chi-square test used for comparison analysis, but some said for correlation also. I am confused, so Chi-square is test for correlation or comparison? ...
11 views

### Comparing cells from two crosstabs / chi-squared goodness of fit test?

I have two crosstabs that I'd like to compare for each cell for significance. Both crosstabs have the same variables and the same amount of total observations, but the frequency distribution is ...
16 views

### Comparing success of group 2 and failure of group 1 (cross-tabulation comparison in contingency table)

I'm studying the endowment effect through the exchange paradigm. Participants received an object A or B. Then the experimenter asks the participants if they accept to trade their object with the ...
1 vote
28 views

### I'm having trouble understanding how to perform a very basic chi squared test

I conducted a survey: I asked 50 participants a question about a device they were using "is this device helpful". 30 said "Yes", 20 said "No". How do I proceed with input ...
1 vote
15 views

### Comparing the percentage changes of two Crosstabs (Chi-square test of independence/association)

I'm looking for an association between 2 variables before and after manipulation. I ran 2 separate crosstabs and I'm able to see for which cells there's an association. Additionally, I want to see ...
9 views

### The distribution of a score test statistic in a special case

Suppose that we want to test a restriction $\alpha=0$. Unfortunately, we cannot directly estimate the parameter of interest $\alpha$. Instead, we can calculate the log-likelihood functions with and ...
22 views

### Which statistical test is more suitable?

In an exam question I was asked to consider the following data related to education loan taken or not for pursuing higher education and formulate a suitable hypothesis and validate it by using an ...
12 views

### multiple chi-squared tests for concluding divergence over representation in a group

I try to distinguish under which group a specific instance is over-represented, if any. My data has 3 groups (columns), and 150+ instances (rows), and the values are counts each instance is present in ...
10 views

### How to work out confidence intervals for the following two scenarios? (please see description below)

I've got a linear regression sas output. So, I know the standard error from there. I need to work out the 95% confidence interval for the change in y as x increase by 1, which is basically the ...
17 views

### Test to find expected outcome

I have a list of genes and I tested if these genes are associated with a disease by using the genome-wide association summary statistics dataset. Chi-square statistics was used and after performing ...
10 views

### Chi-square in genetics with fruit flies. Getting 0 observed when the expected was more than 0, and got an unexpected phenotype. How to handle?

We crossed fruit flies in genetics class and I ended up with very different results than the expected values. For some values, I had 0 observed when the expected was more than 0. Would I go through ...
13 views

### Chi-Squared Test of Association Equivalent for 3 Categorical Variables and Observed Frequency [duplicate]

Originally asked on StackOverflow and now brought over here upon recommendation from another commenter. I'm an undergrad writing a very simple lab report in which I'm analysing some data on observed ...
43 views

### How do I use a chi squared test for homogeneity/other statistical method for this situation?

I am performing analysis on data of ~8,000 patients who have COVID. This is my scenario. I have information of each patient being classified as either severe or non-severe in how COVID-19 affected ...
18 views

### Using estimates for chi-square test for sample size estimation for logrank test

Is it possible to use estimates for chi-square test to estimate sample size for logrank test? I remember that I have seen papers that do it that way. The problem is that, when you have to estimate ...
35 views

### Conflicting Chi Squared and Cramers V result

I'm trying to test whether ski skill level has an impact on an athlete's motivation to visit a resort. I have three skill-level categories and three motivation categories. I have calculated my chi-...
25 views

### Why does sklearn's Chi2 test return different results when a feature is present or absent?

I am doing text classifcation and using SciKit Learn's Chi-square test to select features. Reading about the Chi-square test, a word being present in a text should be just as predictive of a class as ...
40 views

### Weighted chi square gives significant p value but Poisson regression doesn't

I have a problem which never happened to me before. I am testing for a binary outcome (yes/no) treated vs non treated. I have performed a weighted chi square test using ...
1 vote
26 views

### Box-Cox parameter confidence interval clarification

In their original publication, Box and Cox state ...we can obtain an approximate $100(1 - \alpha)$ per cent confidence region [around $\hat{\lambda}$] from  L_\text{max} (\hat{\lambda}) - L_\text{...
146 views

### How does one calculate the p value for a two tailed chi square test with degree freedom of 1?

How does one calculate the p value for a two tailed chi square test with degree freedom of 1? ...
71 views

### Compare chi-squared goodness of fit results for Poisson and Negative binomial

Steps followed for testing : Derive parameter estimates using fitdistr() function in MASS package for the dataset, dt ...
39 views

### ZINB vs binomial model goodness of fit testing

I have read that the Vuong test is no longer considered appropriate for testing whether a ZINB fits better than a negative binomial test because it is not strictly non-nested nor partially non-nested. ...
1 vote
15 views

### Informative priors for Bayesian chi-squared test

A colleague recently presented results from a chi-squared test that used a Bayesian method for estimation. The results seemed promising, but when I looked up the main function ...
559 views

### Chi squared for goodnes of fit test always rejects my fits

I am using lmfit to fit a function in Python. This is my fit: Log scale: Lin scale: where the histogram is my data and the dashed line the fit. The error bars are ...
8 views

### Combining multiple observations across quadrats to estimate relative frequency: how do I account for "unobserved" species?

I am trying to figure out if/how I can understand if animals are choosing particular plant species for foraging or just using them based on their availability. To do this, I need to characterize the ...
14 views

### Effect size for comparing two models using anova(test="Chisq") function in R

How do I get the effect size (e.g., Cohen's w) for a comparison of two models using anova(lm.1,lm.2,test="Chisq") function in ...
39 views

### Can I use the chi squared test to check a sample is representative of my population across multiple categories?

I was wondering if I could use the chi square test to see if my sample % split size is representative of all the splits. I know I need to use integers and not %. So, could I multiply my split % by my ...
1 vote
22 views

### Could someone please help me understand how to choose a method for testing goodness of fit (model compared to measured data)?

I calculate models that describe measured data. Most people in the field don't attempt anything statistical (the models have many potential sources of uncertainty). However, I want to do a better ...
38 views

### What statistical tests should I use?

I am comparing the association between BRCA1 gene mutations and the prevalence of ovarian cancer by ethnicity (5 ethnic groups). I collected data on the number of patients who develop ovarian cancer ...
20 views

### I don’t know if chi-squared is appropriate

I collected data among individuals- I took noted screening results they had within the last year, collected a baseline screening, and another follow up 3 week screening. I’m comparing the 3 screenings ...
107 views

### Calculate effect size Cohen's w (omega) for a chi-square test in model comparison

I have two logistic mixed-effects models, nested within each other and differing in only one fixed variable: ...
12 views

### Does the limiting Chi-Squared distribution for the Deviance statistic hold for Poisson Regression models?

It is a well known result for Logistic regression that the Deviance statistic approaches a Chi-Squared distribution if two assumptions hold: the number of observations aproaches infinity the number ...
45 views

### svychisq with statistic="Chisq" vs. statistic="adjWald"

I'd like to run analyses using Rao-Scott Chi-squared test using svychisq to account for survey weights. It seems that statistic="Chisq" gives the Rao-Scott version, however, now that I'm ...
1 vote
15 views

### Which test to use to compare multiple choice answers for two groups of survey questions

I have a situation where there are 200 scenarios presented in group A, and 200 scenarios presented in group B, and I have a small panel of 4 domain "experts" choose between 3 options for ...
1 vote
29 views

### Chi square reporting df for 2x1

I conducted a 2x1 chi square and need to report it in APA. There are 280 in the sample. Do I deduct the df from the sample size? e.g. X2 (1, N=279) Thank you
1 vote
13 views

### Are there special sample size calculations involved for the analysis of residuals in a contingency table?

This is a purely theoretical question (for the moment at least), so not a lot of details to share. If I plan an analysis of residuals following a chi-squared test of independence, I was wondering if I ...
From this post, Confidence regions on bivariate normal distributions using $\hat{\Sigma}_{MLE}$ or $\mathbf{S}$, the equation \$(\mathbf{x} - \boldsymbol{\mu})^{T} \mathbf{\Sigma}^{-1} (\mathbf{x} - \...