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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Can the χ² test be used without a contingency table?

I thought that the chi squared (χ²) test is to be used when one has an r × c contingency matrix, i.e., when the dependent variables are nonnegative, span the same <...
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Statistical Analysis for Physics Research Project [closed]

Important concepts for Problem: $\chi^2$ test, $p$-value, $\sigma$ Significance I am an undergraduate Physics student working on a research project which involves a certain level of statistical ...
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1 answer
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Weird results from Chi Square test

I'm running a chi square test on some categorical values pertaining to race, and whether different racial groups participated in a clinic. As there's about a dozen different races in this data, I ...
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Does Fisher exact test impose restriction on sampling design? [duplicate]

It is known that Fisher exact test assumes that all 4 margins of 2 by 2 table are fixed. $\chi^2$ test does not impose restriction on sampling design beforehand in general where I mean $\chi^2\sim\sum ...
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1 vote
2 answers
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How many tests do I need to run?

My hypothesis is that the wording of a particular yes-no question affects whether people will answer "Yes" or "No", such that Wording 1 is more likely to be answered "Yes"...
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Appropriateness of Chi Square in finding correlations in data set [closed]

I'm trying to determine correlations between different rows of categorical data in my given set. Different columns include race, sex, language, insurance type, etc., whereas the target variable is if ...
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Interpretation of significant predictors in logistic regression

I am approaching an exercise about data analysis, but I have some doubts about interpreting my results. I have $p$ predictors, some categorical, others continuous (let's call them $X_1$, $X_2$, $\dots$...
1 vote
1 answer
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Chi-Square to P-Value - Basic Stats

In a review problem for a class, we were asked to perform a Chi-Square Test Statistic for a 2x2 Table without a continuity correction. In the answer key, my professor included the following: I ...
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2 votes
2 answers
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Statistical test recommendation for efficacy of three different drugs with categorical responses

I have a really small study sample of 70, in which they are being medicated with 3 different drugs (A,B,C). The study aimed to determine the efficacy of each drug in treating the disease and the ...
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1 answer
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Can I run multiple chi-square for each conditions?

HI supposed I have these conditions. ...
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Is this simple, univariate logistic regression valid?

I am working on a research project. We have roughly 300 study participants that have been categorised into 4 groups. Some of these participants had a recurrence of a disease, and the rest did not. I'm ...
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Confused about random variables and time series

I have this two practical (with R) exercises for my exam: Using $\chi^{2}$ to test (goodness-of-fit) if fluctuations in wind speed are Gaussian. Calculating Lagrangian time scale for wind speed. In ...
3 votes
2 answers
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Is there a Relationship Between Variance and Chi-Square?

I am an MBA Student that is taking courses in Statistics. Up until now, we had only encountered "Chi-Square" in the context of Contingency Tables. That is, how to find if the difference ...
1 vote
1 answer
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Why do we use the limiting distribution under the null hypothesis when computing power in Monte Carlo simulation?

I'm computing the power of a statistical test using Monte Carlo simulation. My test statistic is asymptotically $\chi^2$ under the null hypothesis. When I am computing the power for a given iteration ...
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Classifying multivariate data as gaussian, non-gaussian, or a mixture of gaussians?

It's for the following use case: I have a set of "detects" of a group of individual targets (mostly stationary) that I wish to cluster or segment such that each cluster (group of detects) ...
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What are the relevant null distributions to infer the results of a simulation that renders a multinomial distribution with three possible results?

I have simulated 10 000 occurrences of a soccer match, by generating random numbers from 0 to 1, and then passing these, and the adjusted expected goals by team for the match, through an inverse ...
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Analyzing frequency of events in R

I have data on fire incidences: structure(list(Season = c("Winter", "Winter", "Winter", "Winter", "Winter", "Winter", "Winter", &...
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1 vote
1 answer
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Determine if a categorical variable occurs at a frequency greater than chance with a boolean outcome

I am looking for the proper statistic to answer whether which categorical items (from a long list) occur at frequency greater than chance with each state of a boolean variable. More specifically, I ...
0 votes
1 answer
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Chi-squared for repeated measures for 2 by n

I have data on patients who have two gastric samples drawn to culture bacteria. I would like to see if gastric pH (categorized as acidic, neutral, or basic) has an influence on the dichotomous outcome ...
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Statistical test to detect a difference between treatment and placebo while taking into account a group effect

I want to see if there is a significant difference in various parameters between animals given a treatment vs. animals given a placebo. Around 100 animals from 5 different farms were involved in the ...
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1 answer
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Chi-square Test with Specification of Null-Hypothesis Interval

I have a large sample (N > 1.000.000) of a population. Each individual has a treatment associated with it and a class label. There are five actual treatments T1..T5 and there is a reference ...
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Which test do I use to compare if there is a significant difference in a binary outcome at two time points within the same group?

I have a fixed group of 60 samples, with their serology status (adequate vs inadequate) at 2016 and 2018. Typically we would do this yearly, but I am interested to find out whether missing out a year (...
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3 votes
1 answer
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Is the MLE variance estimator for the normal distribution asymptotically normal?

In textbooks, it is mentioned that the maximum likelihood estimators are asymptotically normal. I am having trouble with understanding how this can be true for the estimator of variance (for example, ...
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Hypothesis Testing Seasonality in Time Series

Is there any direct hypothesis test in Python that would test for seasonality in a time series without having to decompose the series and interpret the plot?
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chi-squared for experimentation analysis - how to adjust for prior difference?

If using chi-squared test of independence to check if treatment group has affected the distribution of a binary outcome (e.g. click vs non-click), but there is also prior difference in click rate ...
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1 answer
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How can I find the strength of relationships between rows and columns in a non-mutually-exclusive contingency table?

I'm an English teacher doing some research, and need help finding the right statistical tool. Here's the basics: I have transcribed hours of student conversation from audio recordings as they played a ...
1 vote
3 answers
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Is it possible to perform post-hoc interaction contrasts within a chi-square test?

There are many questions on this wonderful site about post-hoc contrasts within chi-squares, however none of the posts I have seen have quite answered the questions I have about the procedure. I will ...
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1 answer
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what does it means if two variable with exactly the same Wald Chi-Square?

After I run the program, it shows two variables with exactly the same Wald Chi-Square, how can I interpret these statistics? Can I say that it is Quasi-complete separation that a single level of a ...
1 vote
1 answer
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Why does this test do not follow a chi-square distribution?

I am trying to run some simulations to implement a test that is supposed (according to the theory) to follow a chi-squared distribution with 1 degree of freedom. My setting is as follows: The data $...
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2 answers
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Why are ztest and chisquared test not returning equivalent sample size results?

I'm using the statistical software G*Power to find the minimum sample size needed to detect whether or not the difference in two proportions is statistically significant in an AB test I'm setting up. ...
1 vote
0 answers
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The right test to check whether the two tables are independent from each other [closed]

Table A Group Year 1 Year 2 1 0.4 0.45 2 0.3 0.33 3 0.2 0.6 4 0.1 0.12 5 0.07 0.11 6 0.03 0.06 7 0.01 0.02 Table B Group Year 1 Year 2 1 0.43 0.42 2 0.313 0.39 3 0.223 0.65 4 0.112 0.18 ...
5 votes
2 answers
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Goodness of fit for exponential model in lmfit

I'm having a dataset where I measured the growth of a given molecule over 7 timepoints. The growth can be described by the formula: $(P_{0} - plateau) * e^{-k t} + plateau$ , where k is the growth ...
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1 answer
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How are the confidence interval of Cramer's V and the Chi square statistic related?

I wondered about the relationship between a confidence interval for Cramer's V (I used the rcompanion package and the command cramerV(table, ci = TRUE)) and the result of the chi-squared test (I used ...
0 votes
1 answer
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SPSS, how to properly interpret adjusted residuals in crosstabs with chi-squares larger than 2x2?

I would greatly appreaciate an easy to understand answer. To my understanding if the adjusted residual is +/- 1.96 or more (or less if negative) then something is going on. What exactly does the ...
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1 answer
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chi square, greek or roman?

I would like to report a chi square statistic evaluated from an experimental population in a manuscript. Do I use (1) the lower case Greek letter ($\chi^2$), (2) the upper case Greek letter ($X^2$), ...
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Is it possible to do a contrast in a 2x2 (or more) contingency table or am I completely missing the point?

I have the following 2x2 contingency table of observed frequencies: ...
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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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1 answer
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What is the $\chi^2$ contingency test really showing?

I have a friend who used this function to compute a chi-squared contingency table in a paper they are writing, and I don't think I fully understand what the results of this test are. Function ...
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Statistic tests in "table 1" - which to choose?

I have made a table overall comparing two cohorts - a "table 1". The table includes gender, age and 2 different scores from the two cohorts. I would like to test if gender, age and the 2 ...
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Calculating Critical Value for Mixture of Two Chi-Square Distributions

Let's say I have a statistic X which is distributed as a mixture of two chi-square distributions; $$X \sim 0.5\chi^2_1 + 0.5\chi^2_2.$$ I'm wondering how I can calculate the critical value(and p-value)...
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2 answers
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Chi squared test with reasonable sample size results in R warning

I am trying to identify whether a specific sample is likely coming from a certain data population using the chi squared test. I use R to do the calculation and my ...
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Chi-Squared Goodness-of-Fit... with Probabilities?

For background, I am working on a sabermetrics project where I predict probabilities of events with Naive Bayes classifiers. I calculate the observed expected-value probability from the test-set ...
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1 answer
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Quantifying Dependency in Chi Squared Test

I am running a Chi Squared test on nominal values and this is the contingency table. ...
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Chi squared min / max (as in best / worst possible fit) values

Naturally the answer to the former would be 0 in case of a perfect fit. But how would one go about finding out the value of the worst possible fit? Background: Doing a simple experiment to crack ...
2 votes
0 answers
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how to compare percentages of intervention group before and after interventions? (repeated dependent variable are presented in categorical variables)

I am conducting a randomized controlled trial, and after intervention, the numbers of patients with some characteristics (for example, prediabetes or IGT) have changed. I want to compare the ...
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2 votes
0 answers
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Chi square statistics (chen & thissen, 1997) for local dependence testing in IRT models

I have recently computed the test for local dependence based on X2 statistics (Chen & Thissen, 1997) in RStudio with the mirt package like this: residuals(fit.SKIDDETdisc, type = "LD", ...
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1 vote
1 answer
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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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How to compare observed versus expected ratio data between two independent, unpaired groups with different sample sizes?

so I'm comparing the expected fitness of double mutant animals (based on independent, additive effects of each corresponding single mutant) to the observed fitness of the double mutant. The data is ...

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