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

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How do you do a log-linear analysis in r?

I can't seem to find anything on log-linear analysis. Does anybody know how to do them in r? I have two variables: one a dependant one (yes or no recoded as 1 or 0) and an independant one with 5 ...
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1answer
20 views

Pearson's Chi Square test (Goodness of fit)

I have two arrays that I would like to do a Pearson's Chi Square test (goodness of fit). I want to test whether or not there is a significant difference between the expected and observed results. ...
1
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0answers
8 views

How to calculate non centrality parameter?

Suppose $Y\sim N_p(\mu,\sigma^2I_p)$. Let $A$ be a symmetric idempotent matrix. I want to show $Y^{T}AY$ follows a chi-sq distribution with some non centrality parameter. Suppose ...
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15 views
2
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2answers
43 views

$\chi^2 $ of multidimensional data

I want to test if two observations of nominal data accord to the same distribution. I am using the chi squared statistics to perform a chi squared homogeneity test and normalize the result with ...
3
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1answer
41 views

How to to find and evaluate optimal discretization for continuous variable with $\chi^2$ criterion?

I have a data set with continuous variable and a binary target variable (0 and 1). I need to discretize the continuous variables (for logistic regression) with respect to the target variable and ...
3
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1answer
34 views

How to interpret the residual colors on a mosaic plot?

This is a mosaic plot of contingency table dataset HairEyeColor described here. How do I interpret the colors representing residuals? What is the difference ...
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33 views

What test is appropriate for my data set?

So my data is on feedback students receive during their 4 years at university. I sent out a questionnaire and there are 23 questions in total, each question is looking at the perception and value of ...
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0answers
21 views

Chi square P value

I have got 1.000 Exact Sig. (2-sided) by using Chi Square. Just wondering is that significant? as I am not good in SPSS and related stuff.
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15 views

How is p-value performing as a measure of association?

It's known that Cramér's V (Chisq adjusted for table dimension and sample size) is a good measure of strength association. But what about the p-value? P-value (as a probability of the numbers we have ...
3
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1answer
42 views

Determining $\chi^2 $ for Cramer's $\phi $

I intend to determine Cramer's $\phi$ for two contingency tables of the following form: ...
0
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1answer
19 views

Distribution of sum of mean squared errors - weighted sum of chi squared distributed variables

Suppose $X,Y$ are independent chi-squared distributed random variables with $m,n$ degrees of freedom, $X \sim \chi^2(m)$ and $Y \sim \chi^2(n)$. What is the distribution of $$ Z = \frac{1}{m} X + ...
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19 views

Phi correlation for multiple cells

I have this table for chi-square in R: x <- matrix(c(23,22,10,14,11,12),ncol=3) phi(x) this is a 3 by 2 table and thus phi correlation won't work here, can ...
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34 views

Correlation, probabilities and alternative grading system in high school problem [closed]

For strictly educational purposes, our fictitious high school utilizes a GPA grading system represented by ordinal variable ranging from 0 to 4 (5 potential inputs) and the board test submitted for ...
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0answers
13 views

Differences in variables constructed by counting.

I have constructed a frequency variable from counting events of certain magnitude (e.g, 1,2,3...) from a time dependent experiment with animals. I have two groups (Trained vs Control) and two phases ...
0
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0answers
28 views

Mahalanobis Distances Critical Values (Chi-Squared?)

Say I work out the mahalanobis distance 'D' to measure the separation between two objects (which aren't normally distributed). Say I now want to use 'D' against some critical values to decide if it's ...
0
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2answers
55 views

Chi-square: naïve compensation for low frequencies

As far as I understood it, chi-square provides a measure for determining the similarity of the expected and observed (empirical and theoretical) distributions of nominal variables. It can be employed, ...
2
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0answers
17 views

Show Pearson Chi-Square Statistic is Score Statistic for Multinomial Data

I've read in many textbooks that the Pearson Chi-Square statistic is a score statistic in the multinomial setting (as well as others). I thought it would be a good exercise to derive this, but I am ...
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16 views

R: weighting with two variables while boostrapping

I have two variables that I'd like to analyze with a 2x2 table, which is easy enough. datatable=table(data$Q1data1, data$Q1data2) summary(datatable) However, I ...
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1answer
31 views

Is this the correct way to calculate the mean and variance of $(X-n)/(2n)$ where $X$ follows a Chi-squared distribution with $n$ degrees of freedom?

Let $X_n$ follow a Chi-squared distribution with $n$ degrees of freedom. I would like to study the variance and mean of $$\lim\limits_{n \rightarrow \infty} Y_n := \frac{(X_n-n)}{(2n)}$$ I would also ...
2
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1answer
31 views

How to run Chisq independence test using monte carlo method

I've been investigating exact tests and during that I find monte carlo method very useful. I can write my own code for randomization and permutation tests but I cannot figure out how R function ...
4
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2answers
89 views

Testing for similarity on count data

Is there a statistical test tat can test for similarity between two data sets on a count data? The only test I can think of doing on a count data is chi squared test and fisher exact test and both ...
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0answers
21 views

wald test and score test, normal or chi square?

I learnt from section 10.3 of statistical inference that both Wald test statistic $\frac{W_n-\theta_0}{S_n}\approx\frac{W_n-\theta_0}{\sqrt{\hat I_n(W_n)}}$ and score test statistic ...
2
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1answer
84 views

p-value in odds ratio and regression

I have a few questions about the p-value. Firstly: Let's say we have a p-value of 0.52 in a contingency table analysis with a sample size of 60. If the sample size would be 90 with the same sample ...
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0answers
25 views

Mixing chi-squared and fisher's exact tests

I'm trying to look across a dozen or so groups of cases with respect to a condition they may have or not. I have a predetermined expected frequency for each condition status (c1 & c2, let's assume ...
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25 views

Additivity and linear combination of chi-squared distributed variables

I am trying to get a better understanding of the Satterthwaite pooled degrees of freedom estimation, which led to understanding the general problem of pooling variances. My confusion, in short, is ...
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16 views

Does consolidating groups in chi-squared change the df?

I'm running chi-squared goodness-of-fit tests on answers to a series of questions. I originally had 5 options (Strongly Agree, Agree, Neither Agree nor Disagree, Disagree, Strongly Disagree) but I ...
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22 views

What is the best way to find the strength of the relationship between two factors?

I am not a statistician, so forgive me for not being accurate with my question - if you have advice on how better to rephrase the question I am open to it. I am trying to compare two rating systems to ...
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1answer
36 views

3 categorical IV and 1 categorical DV — what test to use?

Here's my setup: Independent Variables (IV): (A) Task -- values 0 - 6 (order doesn't matter) (B) Viewpoint -- values 0 - 26 (order doesn't matter) (C) Input-device -- values {touchscreen, mouse, ...
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0answers
8 views

Permutation test for 3 variates

I have 3 covariates, which are merely count data. They have 3 different means. How can I get a unique p-value or how can I compare them? The aim of my study is to know if those populations are ...
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0answers
26 views

Advice for test on categorical variables

I am working with two variables - variable 'A' is an independent categorical variable and has three levels 'a' 'b' and 'c'; variable 'B' is continuous response variable data I have classified into ...
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0answers
16 views

Stata: Test if fixed effects are needed

In Stata, what is the command I should use to test if fixed effects are needed in my panel data regression? The output to test for redundant fixed effects should be Cross-section F-Test ...
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1answer
56 views

How to find nearest neighbours to a dataset?

I came across a (maybe simple) problem. Consider I have an "observation" vector of 12 values, called $O=[o_1,o_2,...,o_{12}]$. What would be the best way to compare $O$ to a "theoretical" database of ...
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489 views

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 ...
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11 views

Squared Normal RVs Divided by Sum of Squared Normal RVs

Suppose we have $d$ random variables $X_1, X_2, \cdots, X_d$ sampled from the standard Gaussian N(0, 1) i.i.d. What's the distribution of the following identity? $$\frac{X_1^2}{X_1^2 + X_2^2 + ...
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0answers
13 views

Relation between chi-squared statistic scores and classification accuracy

I am evaluating the utility of two distinct sets of features for solving a given supervised classification problem with two classes. I am using the chi-squared statistic as a feature selection ...
4
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1answer
16 views

Two rate chi squared tests infection rate

We would just like to display a crude statistic to compare infection rate pre/post intervention. Based on a paper I read the statistical test I need to apply is a 2 rate chi squared test. I've been ...
3
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1answer
84 views

Chi-squared-like test with absolute instead of squared differences for calculating test statistic

I am looking for a test which works exactly like the chi-squared test but instead of calculating the test statistic as the sum of squared differences of observed and expected values divided by ...
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1answer
12 views

Which statistical test for statistical significance of positive result in 5 categories of samples

I have 5 categories rock samples and I am trying to understand how their fossil preservation differs and whether the difference is statistically significant. I determined the presence or absence of ...
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12 views

A chi-squared test for a matrix of data

Given a observable vector $v=[v_1,v_2,\ldots,v_n]$ and a model $m=[m_1, m_2,\ldots, m_n]$ when $\sum_i v_i=\sum_i m_i$, I can use chi-squared to determine the likelihood that $m$ is a good model for ...
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18 views

How can I test for changes in the distribution of categorical data over time?

Each week at my organization, we receive X number of type A messages, Y number of type B messages, Z number of type C messages...etc. I want to be able to test if the distribution of these message ...
1
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1answer
44 views

Using contingency tables for testing multiple dependencies

I know that I can determine the correlation / association / dependency between two variables (X= smoker, and Y=cancer) using chi-squared with a 2x2 contingency table: ...
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1answer
23 views

Determining whether a successive instances are conditional or independent

I hope I can appropriately describe the problem. I have an example data set with 610 individuals with made up analogy (it's not really about cars). I want to determine the number of people have x ...
0
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1answer
28 views

Any reason to report a Chi Square Test of Independence on a 2×2 table when I'm already reporting a 95% CI on the odds ratio?

I'm analyzing a 2×2 contingency table, and am going to a report a 95% CI on the Odds Ratio. Is there any point in prefacing this with a Chi Square Test of Independence? I understand that if the Odds ...
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0answers
16 views

min ChiSquare to fit dipole axis

I am trying to fit a dipole. As I am not sure about some aspects (and not sure whether I understand it at all) I would like to ask this question here. Basically I have a distribution of $n$ sample ...
0
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0answers
27 views

Best statistical analysis method for frequency data

I'm designing a between subjects experiment with 1 dependent variable with 2 levels (manipulation & Control) and 4 dependent variables which are all categorical (Yes/No). I would like to see the ...
1
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1answer
43 views

Test if two gamma distributed populations are different

I have data from two populations of different sizes. Both have Gamma distributions with different shapes and scales (as estimated in r): fitdistr(x/10000, "gamma") #186 members shape 0.586219900 ...
5
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1answer
56 views

Finding quality of fit for two discrete variables with low statistics

I have data from an experiment which I am trying to explain using a model. I do not have an analytic formula for the prediction of the model but instead I got its prediction through a simulation. The ...
0
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0answers
17 views

Comparing the expected and observed values of each item in a dataset separately

I have a set of points and for each point I have both observed and expected values. How can I compare the difference between the observed and expected values are significant for each data point. Note ...
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46 views

Approximate normality of distribution of counts in contigency table

I seem to be struggling with lack of basic understanding of some important concepts. This is a question to the answer of @Glen_b in this post: Warning in R - Chi-squared approximation may be ...