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Questions tagged [chi-squared]

A test (typically of distribution, independence, or goodness of fit) or a family of distributions related to such a test.

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Are degrees-of-freedom corrections necessary or possible for the exact multinomial goodness-of-fit test?

As the title: I have a discrete distribution with a small number of categories. I want to test if it is compatible with a parameterized distribution. If I were to do a chi-squared or G-test, I ...
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Defining my number of multiple comparisons for a Bonferroni correction

I'm a grad student doing analysis on a survey. One of the things I want to note from this study is whether demographic factors of respondents are connected to the answers they gave (how do men or ...
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How to compute multiple Chi^2 P-values for each of a factor in a 3-way contingency table?

How were the p-values calculated using chi^2 (method cited in paper below) in the following table. Its a three way contingency table, tumor stage 1-4, race B/W and hospital city/university. They have ...
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Can I perform a McNemar's test with only proportion and denominator information?

I have the following count and denominator information. The 630 subjects are the same people over two different periods of time. Can I conduct a McNemar's test to compare the dependent proportion ...
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What i have to do after i'm Working with tf idf and chi square [on hold]

In text mining, i wanna ask what i have to do after I did a tf-idf and chi-square for every terms. Tf-idf is like a different file with chi-square. Right? Is it right if I did a tf-idf matrix ...
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+50

Describing Specialization

I am trying to formalize an observed trend. To simplify what I am trying to do, suppose a dataset of salesmen selling items A, B, C, D. In the year 1950, the proportion of each sold is (0.2, 0.2, 0.1, ...
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How IBM SPSS calculates exact p value for Pearson Chi-Square statistic?

Usually, I use Fisher's exact test p value when the sample size is small for Pearson chi-square test. Then I realized that IBM SPSS reports exact p values for all the tests (i.e. Pearson Chi-Square, ...
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Is the Chi-Square Test of Independence the best option for 3x2 contingency table?

I have some data which in the terms of a 3x2 contingency table look in the following way. ...
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Degree of freedom on Titanic Dataset

I am working on Titanic Dataset and I was trying to figure the relationship out between gender and surviving situation with Chi-Square Test. In a first glance, I said that there is four different ...
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How to Code & analyze multiple response questions in SPSS? [closed]

After exporting my data from Qualtrics to SPSS. The multiple answer options did not fit as assumed into the variable view. Instead of having (age) IV --> channel (DV) with several options, it ...
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Comparing the distributions of proportions in two groups

I'm comparing the total dog population in a region with the number of dogs in rehoming centres in that region. The data are below. The number of cases is the number of dogs that have been in rehoming ...
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Interpreting Pearson and Deviance residual graphs

Using a generalised linear model and predicted probabilities, I have been able to plot the Pearson residuals and Deviance residuals. I did this in order to have goodness of fit measures for the model. ...
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Test if generated image is considered as real image

I am planning my bachelor's thesis and I am going to write a new image generator. To evaluate it, I want to do an online questionnaire. I want to find out if people are able to differentiate between ...
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Score of importance from feature selection techniques

Can I get the score of importance for each feature in feature selection methos such as Chi2, Information Gain (IG), or Recursive Feature Elimination (RFE)? Or they just provide a list of important ...
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Goodness-of-fit glm: Pearson's residuals or deviance residuals?

I want to evaluate the goodness-of-fit (or badness-of-fit) of a negative binomial glm. However, even here within CV, I've seen multiple different approaches for doing so. Some use the the residual ...
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Can I test for inequality in H0 using chi square test?

Let's say I want to test whether an $n$-sided dice is not too unfair. In the standard chi-square test we test the zero-hypothesis $$ H_0\colon (p_1,\dots p_n) = (1/n,\dots,1/n) ,\quad\text{i.e.,}\quad ...
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Expected counts of Pearson's Chi-squared test for goodness of fit

Assume that I want to test whether two groups have the same proportion of success. Hence, my null hypothesis is $H_0: p_1 = p_2$. I collect data from $10$ individuals per group and I observe $1$ ...
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Goodness of Fit test for Logistic Regression Model

Data have been collected for 176 students. The response variable is 'Choice of Career' having 2 categories namely 'Academic' and 'Non-academic'. I have taken two explanatory variables namely 'Gender'(...
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Post hoc test for chi-squared with given (unequal) probabilities

I am conducting a chi-squared test to see whether the categories survey respondents mention match the distribution of categories in the population. This test is significant, but I am wondering how to ...
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Why is this chi-squared test negative?

I ran two models, one restricted and another unrestricted.The log-likelihood value of the unrestricted model is however unexpectedly smaller than the restricted one. Could anyone tell me what the ...
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1answer
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Calculating the probability that the standard deviation is above or below a certain value

I'm given $n$ samples from a random number generator that produces normally distributed values. Can I calculate the probability that the standard deviation that the RNG uses is $\sigma > \sigma_{...
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Should the reduced chi-sq of a fit to some points be the same as the reduced chi-sq of a fit through a weighted average of those points?

I have nine data points with three of them taken at x = 2, three taken at x = 4, and three more taken at x = 6. I came up with a straight-line fit for these points, and found the reduced chi-sq of ...
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chi squared to assess the effectiveness of a treatment?

this is probably a weird situation: I am an assistant in a course teaching research methodology, yet I can't quite come up with an answer that satisfies me... My students are drafting a mock research ...
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Categorical Data

I have categorical data tested by chi-square the data looks like: Feature: Software Design Notifications Positive Negative Positive Negative ...
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How to test the significant of multiply chi square tests

I know that if I have a model from which I have a very large sample, so that I can create a null distribution. And I also have an experimental sample, I can use the ChiSquare test (or FisherExact test)...
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How to find confidence interval for variance?

Well, I'm taking a statistics class online, and the problem goes like this: Drug concentrations​ (measured as a​ percentage) for 25 randomly selected tablets are shown in the accompanying table. For ...
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Create simulation to see whether Chi Squared is suitable

I'm wondering about the following The threshold is that the chi-squared distribution should be a good approximation to the chi-squared statistic under the null hypothesis. As the number of ...
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If I have less than 5 elements in a cell is there a way to use Chi Squared? [duplicate]

I have some data which has less than 5 elements in a cell, which would usually lead to fishers test being used instead. However, I'm unable to use fishers as there's not enough memory for it. chi ...
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Paired variables?

In our research on apprenticeships in early modern times, we have a series of observations (cases), each with several variables. Each observation is unique because of its combination of the variables "...
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Association between an ordinal Likert variable and a nominal variable

I have responses from a 7 point Likert semantic differential scale -let's say from 'Completely Agree' at one end to 'Completely Disagree' to the other- and a nominal/semi-ordinal age groups variable ...
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Largest connected group of identically distributed nodes in d.r.v sample graph

I have come across an unfamiliar and somewhat interesting problem while attempting to write an algorithm for an image processing application and was wondering if any of you had any ideas that might be ...
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statistical significance of A B test if some observation are removed due to errors

I have ran an A/B test and using chi-square test of independence, results shows that group A improves on group B by less than 5% (statistically significant) YAY!!! Unfortunately, after few checks I ...
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Is it ever okay to ignore a low Cramer's V value?

I conducted a survey on college students to assess what demographic variables affected their views of and knowledge towards climate change. There are 11 variables total: Gender Religion Political ...
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chi square distribution as a function of other variables

I'm minimizing $\chi^2$ between some data and a function. The expression $\chi^2 = \sum\frac{1}{\sigma_i^2}(y_i-f(A,B))^2$ happens to be analytically solvable, so I have a value for the minimum $\chi^...
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Evaluating measurement invariance with lavaan and ordered data

I am running a measurement invariance in lavaan in R. I am comparing a measure of sociocultural appearance pressures across White and Black women. Because this is a 5-point scale, I am treating the ...
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Sum of exponential distribution with parameter 1 and chi-square distribution

As the title suggests, why is sum of n exponential distribution with parameter 1 following chi-square distribution with degree of freedom 2n?
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How to understand Chi-squared goodness-of-fit for linear regression?

I am trying to understand a claim from a paper*: The slopes were calculated using least-squares linear regression to fit the level versus X functions. The goodness of fit of these linear ...
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Asking opinion about random forests, chi squared and data permutation

I have a set of data of counts of hares in summer and in winter, which is very unbalanced: winter was too cold, and samplings were taken only in some 20 occasions, while during the pleasant summer the ...
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Finding the correlation between customers' percentage change of amount of money spent to return to store

I could really use your help. I have a data from a local store. The data consists of 79 customers who visited the store at 2 different times and spent different amounts of money each visit. I ...
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How to use RSSI (Received Signal Strength) data to find out a wireless channel model?

I am trying to obtain the distribution of RSSI measurements collected from 802.15.4 devices like Zolertia Re-Motes. These devices provide RSSI values in dBm units with +/-1 dBm error in measurements. ...
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1answer
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Using chi square on unequal groups with unequal repeated trials

My dataset includes four groups (A, B, C, D) of unequal numbers of individuals. Each individual engages in an activity that results in one of three categorical outcomes (X, Y, Z). The individuals ...
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Relationship between customers' percentage change of amount of money spent to return to store

I could really use your help. I have a data from a local store. The data consists of 79 customers who visited the store at 2 different times and spent different amounts of money each visit. I ...
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1answer
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The probability density function of half-chi-square distribution

Let $X$ be a random variable from a chi-square distribution with 1 degree of freedom. The probability density function (pdf) of $X$ is $f(x) = \frac{\exp{(-x/2)}}{\sqrt{2\pi x}}$, $x>0$. In the ...
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Caret: Feature selection with Chi2 / f_classif

I try to classify texts which I have converted to term-document matrices before. I would like to perform feature selection to reduce the number of predictors. In Python, you can do this by means of ...
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In a bivariate normal sample, why is the squared sample correlation Beta distributed?

If $(X_i,Y_i), i = 1, \dots, n$ are independently bivariate normal distributed, with mean $(\mu_x , \mu_y)$ and variances $(\sigma_x^2, \sigma^2_y)$ and correlation coefficient $\rho = 0$. Denote $T =...
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A question about selection of appropriate test procedure in Testing of Hypothesis

Q. Let (X, Y) be a paired response measured in continuous scale and obtained by administering a a certain drug on a patient. Let 'm1' and 'm2' denote the expected responses. Under suitable assumptions,...
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Showing a Normal and a Chi square are independent

Student's t distribution is defined as the ratio of a standard normally distributed random variable and the square root of a Chi-square distributed random variable divided by its degrees of freedom, ...
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Stats for habitat preferences

I have what I think is a three level contingency table, with time spent in three habitats for two species, and whether their 'condition' was in the presence of a competitor species or not. example ...
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confidence limits on model parameters : Monte carlo vs chi-square

I performed a non-linear fitting on experimental datas to determine model parameters using least square methods ($\sigma$ is the same for all the experimental datas). And now, I want to determine ...
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chisq.test in R with a single vector

(Note: This is a question from a colleague, but I am posting it myself and answering it for posterity, since others might have a similar question.) Usually when you use the ...