# Questions tagged [exact-test]

Statistical tests where the sampling distribution is necessarily exactly correct & not an approximation based on assumptions &/or large sample theory.

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11 views

### Levene Test for fat-tailed distributions

I am trying to perform Levene's Test on two arrays of values representing the frequency distribution of empirical data. I use the scipy.stats.levene package and ...
70 views

### How does Normal approximation work when ties exist for Wilcoxon Signed rank test?

I ran wilcox.test() in R (outcome variable was a test score and the data was paired samples) and got a warning message saying that it cannot generate a p-value for tied values. I saw the R document ...
30 views

### How to perform an exact test of Chi-square for a single-dimension data in R?

I have a data frame like this: > fr.t.r A B C D E Freq 13 3 0 0 0 and I would like to do a Chi-square test to find out if the ...
79 views

### 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, ...
28 views

### when an exact binomial confidence interval should be used?

Is exact binomial confidence interval only appropriate for extremely rare events or extremely frequent events? If so, what are the rule of thumb for the definitions of extremely rare (<0.01?) And ...
165 views

### Exact MCMC Logistic Regression Output

I am having trouble interpreting the output of an MCMC Logistic Regression run using R from the MCMCpack. Unfortunately I have had very little luck in finding sources on the web. I am assuming that ...
55 views

### LRT and $\text{Uniform}(0, \theta)$

We have one observation of variable $X$ that is distributed uniformly on $[0, \theta]$. Null hypothesis is $H_0 \colon \theta = 1$ and alternative hypothesis is $H_1 \colon \theta = 2$. What is the ...
143 views

### Drawing conclusions of several inferences with the same data in one study

In a sample size of 100, we identified the existence of two attributes A and B. Our goal is to assess whether there is any ...
953 views

### One-sided McNemar's test

In R, the function mcnemar.test has the following example: ...
62 views

### Barnard's exact tests - papers?

I am currently writing some essay for the university in which I should give a quick overview over exact methods for independence testing on contingency tables, after writing down the stuff for Fisher'...
151 views

### Boschloo's exact test

I have following data in R: d1 <- matrix(c(24,2,63,11),2,2, dimnames=list(X=c("present", "absent"),Y=c("present", "absent"))) I want to test ...
659 views

### z-test for one population proportion hypothesis with a small sample size

I have asked a "yes/no" question to a small group of people (n = 22). From the 22, 14 answered "yes" and 8 answered "no". I'd like to find out, with 90% confidence, if the majority of my population (> ...
269 views

### Sample size determination for comparing two independent samples with regards to several continuous variables

I am interested in calculating the required sample size to perform several statistical tests on the same sample. More precisely, this is the situation: There are two groups of individuals, A and B, ...
138 views

### Exact Null Distribution with Ties

I am interested in deriving exact null distributions for small-sample test statistics with non-trivial ties. Not fundamentally continuous variables that happen to have a few repeated values, but ...
450 views

### pre-post testing: paired nominal data with more than 2 categories

I have two groups of students who answered a question on the pre-survey about their savings behavior, i.e. choose one answer a/b/c/e/d/f: (a) Save the same amount each week, (b) Save varied amount ...
161 views

### how we do student T-Test?

In my data water is control and gibberellin is positive control. We want do find the activity of steviol against water and gibberellin. How we do student T-Test?. My data of height of plant in cm is ...
116 views

### Covariates in a case control study

I am doing a retrospective analysis on a study has has cases and controls. I am looking to see if there is an association with death, using exact logistic regression. I am confused on whether I need ...
3k views

### Threshold for and Variations of Exact logistic regression

According to this UCLA tutorial exact logistic regression (elrm::elrm in R) should be prefered to the logistic regression ...
380 views

### Exact multinomial goodness-of-fit test as a normality test

We have a practical real-life problem in an open source Linux related project. And I would like to hear an expert review/opinion about the way we are trying to solve this problem. It's been more than ...
2k views

### How do you know if your confidence interval is exact or approximate?

I would like to know the rules between the two, and know how you know the differences.
803 views

### What is the minimum sample size for an exact binomial test of goodness of fit (two-tailed)?

I am doing a two tailed exact binomial goodness of fit test, see, e.g., here. I am looking for something similar as for Chi-square tests, which, as a rule of thumb, require a frequency of 5 for each ...
723 views

### Exact test for m x n contingency table conditional (i.e. fixed by design) on one margin

I have a $m \times n$ contingency table (with $m, n > 2)$ . The experiment yields ~15% cells with expected frequencies lower 5 and also zero counts in the empirical data. The prerequisite for the ...
69 views

### Test of strict difference in independent binomial probabilities

Suppose $X,Y$ are two independent binomial random variables with parameters $n_1,p_1$ and $n_2,p_2$ respectively. Suppose one wanted to test the hypothesis $p_1>p_2$. Conditional on $X+Y=s$, ...
331 views

### Non-parametric, repeated measures two-sample test with small sample size

My data consists in two samples relative to the expression of a given gene, with 4 replications in both samples. I am interested in testing whether the two samples come from the same population, ...
168 views

23 views

### exact test on proportion: confidence intervals vs p value [duplicate]

I have the following 2x2 table NO YES 9690 5 LOW 26354 39 HIGH I want to plot the proportions and ...