Statistical Analysis Stack Exchange
Statistical Analysis Stack Exchange

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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Given the power of computers these days, is there ever a reason to do a chi-squared test rather than Fisher's exact test?

Given that software can do the Fisher's exact test calculation so easily nowadays, is there any circumstance where, theoretically or practically, the chi-squared test is actually preferable to Fisher's exact test? Advantages of the Fisher's exact…
pmgjones
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What is the relationship between a chi squared test and test of equal proportions?

Suppose that I have three populations with four, mutually exclusive characteristics. I take random samples from each population and construct a crosstab or frequency table for the characteristics that I am measuring. Am I correct in saying…
hgcrpd
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Is chi-squared always a one-sided test?

A published article (pdf) contains these 2 sentences: Moreover, misreporting may be caused by the application of incorrect rules or by a lack of knowledge of the statistical test. For example, the total df in an ANOVA may be taken to be the error…
Joel W.
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Warning in R - Chi-squared approximation may be incorrect

I have data showing fire fighter entrance exam results. I am testing the hypothesis that exam results and ethnicity are not mutually independent. To test this, I ran a Pearson chi-square test in R. The results show what I expected, but it gave a…
ferrelwill
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A/B tests: z-test vs t-test vs chi square vs fisher exact test

I'm trying to understand the reasoning by choosing a specific test approach when dealing with a simple A/B test - (i.e. two variations/groups with a binary respone (converted or not). As an example I will be using the data below Version Visits …
L Xandor
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What is the difference between McNemar's test and the chi-squared test, and how do you know when to use each?

I have tried reading up on different sources, but I am still not clear what test would be the appropriate in my case. There are three different questions I am asking about my dataset: The subjects are tested for infections from X at different…
Anto
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Why is a likelihood-ratio test distributed chi-squared?

Why is the test statistic of a likelihood ratio test distributed chi-squared? $2(\ln \text{ L}_{\rm alt\ model} - \ln \text{ L}_{\rm null\ model} ) \sim \chi^{2}_{df_{\rm alt}-df_{\rm null}}$
Dr. Beeblebrox
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How can I test the fairness of a d20?

How can I test the fairness of a twenty sided die (d20)? Obviously I would be comparing the distribution of values against a uniform distribution. I vaguely remember using a Chi-square test in college. How can I apply this to see if a die is…
C. Ross
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How to calculate the p-value of parameters for ARIMA model in R?

When doing time series research in R, I found that arima provides only the coefficient values and their standard errors of fitted model. However, I also want to get the p-value of the coefficients. I did not find any function that provides the…
Lisa
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Is this an appropriate method to test for seasonal effects in suicide count data?

I have 17 years (1995 to 2011) of death certificate data related to suicide deaths for a state in the U.S. There is a lot of mythology out there about suicides and the months/seasons, much of it contradictory, and of the literature I've reviewed, I…
svannoy
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How exactly does Chi-square feature selection work?

I know that for each feature-class pair, the value of the chi-square statistic is computed and compared against a threshold. I am a little confused though. If there are $m$ features and $k$ classes, how does one build the contingency table? How…
user721975
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Comparing two histograms using Chi-Square distance

I want to compare two images of faces. I calculated their LBP-histograms. So now I need to compare these two histograms and get something that will tell how much these histograms are equal (0 - 100%). There are many ways of solving this task, but…
Anton Holovin
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How do I find values not given in (interpolate in) statistical tables?

Often people use programs to obtain p-values, but sometimes - for whatever reason - it may be necessary to obtain a critical value from a set of tables. Given a statistical table with a limited number of significance levels, and a limited number of…
Glen_b
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Pearson's residuals

A beginner's question about the Pearson's residual within the context of the chi-square test for goodness of fit: As well as the test statistic, R's chisq.test function reports the Pearson's residual: (obs - exp) / sqrt(exp) I understand why…
Iain Dillingham
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At What Level is a $\chi^2$ test Mathematically Identical to a $z$-test of Proportions?

BACKGROUND: Skip safely - it's here for reference, and to legitimize the question. The opening of this paper reads: "Karl Pearson’s famous chi-square contingency test is derived from another statistic, called the z statistic, based on the Normal…
Antoni Parellada
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