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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Understanding Chi Square Post hoc test results

I'm using R and comparing the proportion of Male and Female authors from various academic journals (well, I think I am). Here's a table with my raw data: The code for it: ...
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Generalized Likelihood Ratio Test with null hypothesis defined by union of sets

Suppose you have a model with likelihood $ \mathcal L(\theta;\boldsymbol X) $, where $\theta \in \Theta$ are parameters and $\boldsymbol X = (X_1, \ldots, X_n ) $ denotes i.i.d. data. Likelihood ratio ...
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Difference between Chi^2, Chi^2/dof and R^2

I have radioactive decay experiment (so the model is y = Ae^(-kt)) results and am (slowly) teaching myself mathematica to plot this. I want to output some measure for the goodness of fit, but am ...
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Can I use a Kruskal-Wallis test instead of the chi square test of association? [closed]

I need to use a statistical test to test the hypothesis that there is an association between registration categories (registered, not registered, and lapsed registration) and deprivation categories (4,...
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first order statistic of a chi-square? [closed]

I am trying to identify the distribution type of the first order statistic (Y1) of a chi-square sample of size 2 with 2 degrees of freedom.
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Significance of subcategories

My data includes a total sum of around 30 different subcategories. If I want to find if the subtotal of these subcategories is significantly different from previous quarters I can run a chi square ...
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Correction for multiple comparisons for Chi-Square Test of Association?

Mock data: df = pd.DataFrame({ 'Treatment': [1, 2, 3], 'Success': [25, 29, 25], 'Fail': [48, 118, 92] }) Where 'Treatment' represents three independent ...
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diff-in-diff for binary outcome? (i.e.: Comparing proportions of two groups over two time points in paired setting)

Let's say I have students randomly split into two groups (treatment and control). Each student is given a test and they either pass or fail. They then either take a course (the students in "...
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Chi-Square Value too small for df = 6, am I using the wrong number of df?

I'm not very good at statistics so I figured I could ask here to see if anyone could help me. I need to do a goodness of fit test for a table of 7 data points: Energy Observed Flux Expected Flux 0.3 ...
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How to Calculate Degrees of Freedom for a Polygon with Correlated Arcs?

I'm running a bit in circles on this, so hopefully someone has ideas. Problem: I am trying to calculate the degrees-of-freedom (DOF; for purposes of calculating AIC) for a polygon. I am fitting an ...
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What to do after Brown-Forsythe test?

I am comparing the variances of three distributions and am relying on the Brown-Forsythe test. Apparently, at least one of the three distributions appears to have a different variance from the others (...
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Goodness-of-fit for discrete distribution - tails issues

In general, I want to see if a set of values comes from a certain discrete distribution (in this case integers from Poisson, or maybe gamma-Poisson). Chi-squared consistently comes up as the best GOF ...
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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 ...
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Chisquare contingency under 5

I am working with a big data project, iterating over 30k features. There is a prt where I compare between several clusters (after kmeans), part of code: ...
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quasi-poisson / Neg.Bin / Chi-square for analysing annual count data?

I'm interested in looking at annual trends. The numbers represent the total number of a particular animal species that have been counted in that year. We see a decreasing trend, and I would like to ...
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A very big JB value in Jarque-Bera test [duplicate]

I have run the JB test for my data using two different commands. I am quite clueless about what conclusion I can make from the second picture which shows results of 0. This tells me that there is no ...
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Chi Squared Fit Statistic in Structural Equation Models

I am interested in structural equation modeling. I am trying to get to the bottom of how $\chi^2$ is calculated for a structural equation model. I understand that outside of structural equation ...
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Why doesn't it make sense to measure agreement with Chi square?

Why is it more useful to calculate Cohen's Kappa instead of the Pearson Chi Square test to measure the interrater agreement? Could someone please give me an example?
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Question on the chi-square test and Poisson distribution for significance testing

A quick question to check some reasoning: consider the chi-square test for a 2x2 table. For sake of argument, there's 500 patients in each group / category (male and female) and 10% of the total have ...
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Relationships in categorical data

200 study participants read a case scenario (lets make them hair-dressers, it might be less boring for you). Case scenario - male client with thinning hair - what intervention will you apply? Apply ...
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Understanding Pearson goodness of fit and deviation in R - using anova (test= Chisq)

I have run a Pearson goodness of fit and deviance to test the fit of the model but I don't quite understand how to interpret my output. I used an anova to run it: ...
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Finding relationships in categorical data

I have 200 health practitioners choosing one of six treatments after reading a case study. Then i ask them what info from the case study did they use to make their decision - info A, B, C, D or E (...
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Chi-Squared Test of Homogeneity

Consider the table below that gives the proportions of a sample from each of two populations that fall into one of three categories (table edited after @whuber comment). ...
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Hypotheses in bayesFactor for contingency tables

Lately, in a non-English forum, someone asked how she could test counts from two discrete distributions for equal distribution. Her example was (my translation): One study found 76 red, 167 blue and ...
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Post hoc analysis for 3x2 cross tab analysis?

Apologies if this is straight forward. Also please note that I am using SPSS and don’t know how to use R/code. I’m a physician doing clinical research. I’m doing an analysis regarding 3 different ...
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Very small Cramer's V and moderate Odds Ratio?

I'm running a Chi Sq test with 2 binary variables. The data are large (>1 million rows) and not balanced (rare event). The test is statistically significant (p < .0001) and the Cramer's V is ...
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Accuracy estimator for scan sample of categorical time series

Suppose we are tracking the behavior of some agent over time, and this agent can only exist in two states (+, -). This agent is only active for 20 timesteps, but we are only able to observe the agent ...
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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 ...
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Why are baseline rates often excluded from statistical power considerations?

The following (slightly edited) except comes from Georgi Georgiev - one of the most reliable sources on AB testing on the internet. Let’s say you have 300 000 users a month visiting an e-commerce ...
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Which of two parameters was chosen for a sample?

Problem: $X$ is chosen to be $\text{Geom}(p_1)$ with probability $\frac{1}{2}$ and is otherwise chosen to be $\text{Geom}(p_2)$. Given a sample of size $n$ from $X$, guess whether $p_1$ or $p_2$ was ...
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How to demonstrate a significant difference in a proportion

I want to show that if you don't take enough biopsies from the oesophagus for certain patients then you are more likely to not detect an illness . The counts in the table are the number of ...
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Significane versus null hypothesis for small number of data

I have a model that correctly identifies something seven times out of the finite number of 8 data points as true. I was wondering how can I calculate a significance statistics given the very low ...
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Having difficulty understanding a concept about the chi-squared test of independence

I do not understand why chi-squared tests merely indicate the degree of evidence against the null hypothesis of statistical independence and do not give information about the strength of association ...
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Find effect size of chi-squared data

I have data that looks like the following: A <- c(2,20,2,7) I want to do a post-hoc power analysis to check if my sample size is sufficient, but to do a power-...
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Multiple, One Category Chi Square tests vs Single, multiple category Chi Square test [duplicate]

my statistical skills are rather basic so was hoping I could get some insight. Let's say I'm analyzing the demographics of two population groups for variables such as 1. tobacco use, 2. alcohol use, ...
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Both Z-test and chi-squared apply in testing if a pill makes any difference in avoiding the flu?

I want to test if a certain pill would make any difference in avoiding the flu. I give the pill to group A and a placebo to group B. Then I count how many individuals got the flu in each group, and ...
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Chi-square value

I am getting a chi-square value of 1600 for a data, is it possible to get this big value for a chi-square? for 5% risk acceptable risk and 5 degree of freedom the critical value should be 11.070 and I ...
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Which test should I use for Multiple test groups with categorical values?

Here is an example contingency table using R ...
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statistical testing of proportions to include multiple experiments

I am struggling with understanding what is the correct statistical method to use to determine the statistical difference in proportions for multiple experiments. Let me explain my scenario. I have run ...
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Multicollinearity in Logistic Regression - chi-sq tests vs correlation matrix (corrb in SAS)

I have categorical variables (some 0/1, some nominal and some ordinal) and I'm getting different answers when using the two different approaches for deciding if there's multicollinearity. To get the ...
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What am i doing wrong in this Chi-square expectation problem?

Let $X_{1},X_{2},..,X_{10}$ be 10 standard normal variates. Let us Define $T = X_{1}^{2}+X_{2}^{2}+..+X_{10}^{2}$. It is required to compute $E(\frac{1}{T})$. Now, We know that T (sum of squares of ...
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Why does the Pearson chi-square test require to reject the hypothesis?

I generate $100000$ independent random numbers with equal probabilities $\frac{1}{35}$: $\log_2(1),\log_2(2),...,\log_2(35)$. Then I summarize $25$ neighboring values: $S_1=k_1+k_2+...+k_{25}$ $S_2=...
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Understanding the Chi Squared test for Significance Analysis of Unobserved Components in SAS' Proc UCM

Proc UCM in SAS does a Chi Squared test to test the significance of the components found by fitting a UCM model. I want to understand what exactly this test is and how to interpret it. As in, what is ...
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What statistical test can I use to compare proportions across two different groups containing multiple populations?

I am trying to answer a research question about whether the presence of a certain pathogen affects the age structure of frog populations. Study set up: Samples were taken from frogs at multiple study ...
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How to analyze contingency table results? Help with wording to describe observations

I'm learning about contingency tables and proportions. Need help interpreting this table of students interested in one of three subjects by gender. Male Female Science 20 (30.8%) 20 (30.8%) Math 30 ...
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Distribution of probabilities from multiple statistical tests

I’ve been trying to analyze a data set comprised of a small number of human skeletons from 4 archaeological sites in the 800 B.C. to A.D. 1200 time period. Since little is known of the peoples from ...
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Is there an association between the work status of the college students and the challenges facing them?

So I am supposed to do a study about the online learning obstacles. now the research question is as stated as follows:"Is there an association between the work status of the college students and ...
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Is Chi Square test statistic too large to draw conclusions?

I collected some data regarding purchase behaviour (purchasing a black or white car), before and after updating the background color of an e-commerce website. I would like to know if the change was ...
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Chi-squared peak analysis

For a homework assignment I've been asked to play with the titanic data in R. We need to show if class had an effect on survival. A quick visual inspection of the data will show that obviously I ...
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chi square or t-test for this case?

I have collected data on the performance of two different website versions. Both pages have been shown on randomly (but not maybe equally) to different people. So my contingency table is as shown ...

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