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

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Does the birth date of professional boxers matter? Prove/disprove what an astrologer might predict

As a followup to my question about the birth month of boxers, I am posing the fundamental question along with my hypothesis (testing if there is any truth to a conclusion an astrologer might make): ...
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27 views

A reference for Pearson's chi-squared testing

I am wondering if there is a reference for the Pearson's chi-squared test suitable for technically-sophisticated audience that simply presents when the test (in its various forms) is appropriate and ...
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11 views

R function equal to excel CHIINV [migrated]

I'm looking for a function which do the same thing as excel's CHIINV. From Microsoft documentation, the definition of CHIINV is Returns the inverse of the right-tailed probability of the chi-squared ...
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16 views

How to combine clinical variables?

I am dealing with several clinically used variables that are not linked to each others. Those variables are correlated to worsened prognosis (some are numeral and asymmetric, therefore correlations ...
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23 views

Post-hoc Chi Square Test for Pairwise Comparison of 3 Groups

I am trying to do something that in my mind is probably simple and I'm probably just blanking on it. I am using Stata to compare 3 groups on a categorical variable. So, as an example, I would be ...
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15 views

MC to estimate coverage probability of bootstrap [on hold]

I am a novice at R-coding but I am trying to use Monte Carlo to estimate the coverage probability of standard normal bootstrap, basic bootstrap, and bootstrap percentile with bias correction. The MC ...
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47 views

Converting Chi Square Adjusted Residuals to p values

I am running a chi squared analysis in SPSS on a 5 x 2 contingency table. The overall chi square p value was < 0.0005, so I ran post hoc tests (adjusted standardized residuals on the individual ...
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19 views

Confidence intervals for chi square goodness of fit

I'm having trouble figuring this out. I know that you calculate the confidence interval same as you would for a proportion, $p_i= P \pm 1.96 \sqrt{(P(1-P))/N}$, but in my notes it says: ...
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24 views

How to interpret confidence interval with accuracy phrase

Upon reading a peer reviewed article, I found this: A Chi-square test shows that the demographic characteristics of the sample represent Toyota GB’s hybrid customers (data obtained from the New ...
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12 views

chi-squared test vs fisher's test vs … => highly unbalanced length frequency data

I would like to statistically verify if two distributions are identical. Basically, the first distribution is a length frequency distribution from a large population ("population"). The second is the ...
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44 views

Chisquared on categorical data or a Wilcoxon test on the counts hereof?

This question is related to a question I had in R on SO here The background of my question is fairly simple. I was given two "databases" in the form of data.frames ...
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45 views

Finding sampling distribution of normal MLE and likelihood

I'm reviewing old exams in preparation for a statistics final, and I'm stuck on a particular question: Suppose that you have n independent random variables $Y_i$, with each distributed normal with ...
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63 views

How to determine whether a variable is significant using Pr (>Chi) and Df?

I wonder how can I determine whether a variable is significant using Pr (>Chi) and Df? Take following ANOVA table as an example, I know variable type is ...
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29 views

the Chi-squared distribution and Mahalanobis

I'm doing some simulations in C++ and OpenGL (2D and 3D) for navigating a robot in unknown environment known as SLAM. I'm using Extended Kalman filter as an optimal estimator. In SLAM problem, once ...
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28 views

I cannot use Fisher or Chisq test. What now?

I am trying to understand if there is a variance in the counts regarding two categorical variables. Gender Profession Salary F Teacher 12 M Teacher ...
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2answers
26 views

Determining unusual binomial results from a sub-population

If I have a population of 1948 students with a success rate of .154 (301 successes) and I break the 1948 students into their respective majors, how to I determine if the sub-population success rate is ...
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57 views

How to evaluate similarity of datasets based on summary data?

I have summary data that I want to compare to my own data. For the summary data I do not have access to the underlying data, however, I know the percentiles as shown below (A). I also calculated ...
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16 views

Are my data normal? chi-squared for goodness of fit [duplicate]

I have been tasked with determining if my observed data follow a normal distribution. With 119 observations (continuous data from -4 to 4), I was able to create a histogram with 25 bins, and upon ...
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18 views

How to determine if these values are different?

I don't have much stats background (I am a programmer) but want to learn more. I have five long columns of numbers that represent conversion rates (ex. how many successes vs. how many attempts) for 5 ...
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75 views

Hypothesis testing using R

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27 views

Chi-squared Vs Mutual information

Is chi-squared feature selection better than Mutual information based feature selection mechanism?
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158 views

Choice of grouping in Chi-Squared test

Let's say I have a categorical variable. I try to test the null hypothesis that each category has the same count (of something) using a Pearson's Chi-Squared test. I may not be able to reject null ...
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135 views

Transformation Chi-squared to Normal distribution

The relationship between the standard normal and the chi-squared distributions is well known. I was wondering though, is there a transformation that can lead from a $\chi^2 (1)$ back to a standard ...
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397 views

p-value subtlety: greater-equal vs. greater

As I am reading Wassermann's book All of Statistics, I notice a fine subtlety in the definition of p-values, which I cannot make sense of. Informally, the Wassermann defines the p-value as [..] ...
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26 views

Does a well-fitting model have shallower chi-square minima than a poorly fitting one?

I am trying to fit some data with a range of models with some variable parameters, to determine which of the possible models best describes the data. I have noticed that if the model is a poor fit, ...
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power of chi squared test for two proportions with gsDesign package in r

I have problem with calculating power for two sided chi squared test for the following design: Study includes 200 patients (100 patients per group). The null hypothesis is that p1=p2=30% and ...
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28 views

Observed vs expected values for a dataset with repeated measures

I am hoping you all may be able to help me select the appropriate statistical analysis for a subset of my data. I have a population of monkeys that consists of 50 individuals in 3 groups. ...
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77 views

Why does a goodness of fit test use the chi square distribution rather than the hypothesised distribution?

This is a homework(-like) question. I know the answer but don't understand it. If we were to answer the question "Are 5 different groups of mammals equally common?", what test would you perform? ...
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71 views

Compare differences in dependent frequencies

I would like to compare two error rates (proportion of incorrect answers in questions with dichotomous response-format) for two different items, and I am looking for some advice on how to do that. ...
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35 views

Chi square and zscore - chose which one?

I'm newbie in machine learning. Recently I tried to learn something on this and got following concern: I have products classed by categories. Also I have users with gender and device model ...
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24 views

Frequency significantly different from zero

I've got a few frequencies, and I'm trying to work out if each of the frequencies is significantly different from zero. Most of the frequencies I can eyeball, but I wanted to have some for of ...
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19 views

McNemar or chi-square - test for group differences paired and unpaired data

I understand that the difference between a chi-square test of homogeneity and the McNemar test is that the chi square is used for unpaired data and the McNemar is used for paire data. Here's my ...
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12 views

dependent and independent categorical variable across eight trials

Study: significantly selected color for a particular letter. My sample size is 30 and the study is within subject. Independent variable -> letters (total 8)... Dependent variable -> colors ( total ...
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14 views

The chi-square statistics reported above are based on only 2 of 51 units that had sufficient data for computation

So, we are doing a project for HLM class and we realized that for our final estimation for variance components and reliability estimates have this little note under the table. "The chi-square ...
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81 views

In a two-way ANOVA, how can the F-statistic for one factor have a central distribution if the null is false for the other factor?

Consider the two factor additive ANOVA model $$\begin{align} X_{ij} &=\mu_{ij}+e_{ij} \\ \mu_{ij}&=\mu+\alpha_i+\beta_j \end{align}$$ where as usual $\sum_{i=1}^a \alpha_i=0$ and ...
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19 views

Distribution of Standard Deviation of 2 Variable Linear Regression

Assuming we have a fit: $\hat Y= \alpha + \beta (X-\bar X)$ Such that: $Y_i=\alpha+\beta(X_i-\bar X)+\varepsilon$ The standard deviation of $\varepsilon$ is $\sigma$. Estimated in an unbiased way ...
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29 views

How do I convert Cramer's V to Cohen's d?

Say I have a chi-squared test that compares 3 different groups: $\chi^2_2 = 9.81$, $p=.012$, Cramer's $V=.33$ How would I go about converting this to a $d$-statistic? Is the proper approach in ...
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30 views

Chi-squared two sample test for unbinned discrete data

I am wandering through the net but I cannot get a precise description of how to solve this simple task. Two sets of datas ...
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90 views

Is there any correlation or causation here?

I have the following data, where 2 properties (P1 and P2) can be either True or False ...
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29 views

How to perform Friedman's test with covariates

I have 500 participants who each completed 30 trials. In each trial they need to choose the correct image out of three (a three-alternative forced-choice task). Of these thirty trials, 10 trials ...
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47 views

Weird pdf of a quadratic function of a N(0,1) variable: miscoding or big rounding error?

I would like to calculate the pdf of a random variable y defined by : y=c+b*x+a*x^2 The pdf is a non-central chi-squared distribution. For a>0, it should be equal ...
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31 views

What is the distribution of the difference between two Gamma's? [duplicate]

Suppose $X$ is $\text{Gamma} \sim (2,.5)$ and $Y$ is $\text{Gamma} \sim (2,.5)$ and $X$ and $Y$ are independent. Let $Z = 1/8(X-Y)$ what is the distribution of $Z$? I know $X+Y \sim (2+2,.5)$ what if ...
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51 views

Significance testing of categorical variables - is chi squared as good as it gets?

I am testing categorical variables for significant relationships, 5 age groups and 3 answer options (yes/no/don't know). Is there a test which will specifically tell me if e.g. age group 1 is ...
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23 views

Does N-1 correction for Pearson's Chi-Square apply to r x c tables generally?

Campbell (2007) recommended what he called the "N-1" correction for chi-square tests performed on two-by-two contingency tables. He described the correction as: "the K. Pearson chi-squared test ...
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What are the alternatives of a chi square test in testing for changes in categorial data?

I have done a survey trying to understand the waste disposal habits of people. One question is "What proportion of waste paper do you recycle". Another question is "Given a new local policy is ...
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56 views

Why can't the chi squared test be calculated with a row of zeros?

I have some trouble to calculate chi squared statistic with R. My data and code are: ...
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1answer
69 views

weighing the maximum likelihood

I would like to define a log-likelihood (starting with a gaussian distribution) for an observed value of a quantity ($x_i$), compared to the measured value based on a given model ($\hat{x_i}$) and ...
3
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1answer
76 views

Interpreting results of chi-squared

Situation: A/B test of a single website change on a landing page. Alternating visitors to the landing page are shown a variation. The goal is to convert more visitors into customers. With data that ...
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Why is the sampling distribution of variance a chi-squared distribution?

The statement The sampling distribution of the sample variance is a chi-squared distribution with degree of freedom equals to $n-1$, where $n$ is the sample size (given that the random variable of ...
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sample size to estimate variance

I am trying to follow a thread Calculating required sample size, precision of variance estimate? and am facing difficulty understanding a step in the answer, specifically the step given below $ (n-1) ...