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Questions tagged [statistical-test]

A statistical test provides a mechanism for making quantitative decisions about a process or processes.

Statistical Tests

A statistical test provides a mechanism for making quantitative decisions about a process or processes. The intent is to determine whether there is enough evidence to reject a conjecture or hypothesis about the process. The conjecture is called the null hypothesis. Not rejecting may be a good result if we want to continue to act as if we believe the null hypothesis is true. Or it may be a disappointing result, possibly indicating we may not yet have enough data to prove something by rejecting the null hypothesis.

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ANOVA: Error in `contrasts<-`(`*tmp*`, value = contr.funs[1 + isOF[nn]]) : contrasts can be applied only to factors with 2 or more levels

I want to perform a 1-factor ANOVA with 4 levels, ie is.ctl, II, III, and IV. # Tissue grades is.ctl <- grepl("^NB", names(dat)) II <- grepl("^II", names(dat)) III <- grepl("^III", names(dat)) IV <- grepl("^IV", names(dat)) #1-factor ANOVA with 4…
melil
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How to apply statististical tests (functions) on pandas dataframe on combination of subsets of data

I have dataframe which is similar to this one. import pandas as pd import string import random def generate_example_dataframe()-> pd.DataFrame: """ This simple function will generate simple dataframe in long format """ num = 20 #…
Daniel Borek
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How to check two results are comparable or not using K-S test?

I have used two algorithms(methods) on few datasets and obtained some results. Now I want to check whether the obtained results are comparable or not? I have used two sampled K-S test and got the following result, now how to interpret the test…
abc xyz
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How to run the Kruskal-Wallis or Mann-Whitney Test in R?

Can anyone give me a hint on how to run the Kruskal-Wallis Test below? My objective : Is there any significance of the growth (agg_rel_abund) of bacteria between Forest and Urban for each family. The code I have tried in R : kruskal.test(Habitat ~…
Gambit
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Different result of durbinWatsonTest

I know function durbinWatsonTest in package car use bootstrap method to calculate p-value, then the results are different when i rerun this code. Can someone know how to set seed this function? Many tks. df <- structure(list(y = c(-2.59, -3.42,…
Kevin_Nguyen
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Two Tailed and One Tailed T Test in R

Histogram Dataset Boxplot Above is the data and some overview of how it looks. I want to use a t test to find if the mean width between 2 samples from the same population are different (2 Tailed). More specifically, I am interested if the mean width…
Boss Boyd
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Generate batches of random numbers that each are zero-sum and for which mean of the absolute values is uniformly distributed over specified interval

In the context of polls of voting results, I want to generate random numbers with specific properties to sample the possibilities within the margin of error of the poll. For example, suppose I have polling results: Party A: 34% Party B: 25% Party…
thomvil
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What to do when Wilcoxon test returns some 0 p-values?

I'm performing the Wilcoxon test with R in a large List (containing 86 data frames with a variable number of rows and values). I don't understand why after p-values < 10^-307 it returns some p-values = 0 and then it returns with "normal"…
Salvatore D
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my Rainfall Dataset has no Seasonality and is stationary?

I have a dataset (timeseries from 2010 to 2019 rainfall data from various districts near vellore). When I ran the ADF(Augmented Dickey-Fuller Test) i got my dataset to be Stationary! meaning no seasonality! My question is that am I doing something…
om purohit
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Is there Hurdle model function for GAMM on R?

I am working with a dataset that is zero inflated and I found a function that allows me to do a GLMM with the glmmadmb function. But, I realized that my data are not linearly related with the environmental variables I want to test, this is why I am…
Marie Pedaccini
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Statistical testing in R: fisher test and logical variables as binary

I should choose and use right statistical testing between the variable “linolenic being greater than 0.33” and the variable “region being equal to Sardinia”. These are two binary variables, so I'm trying to use fisher.test, but how these could be…
stack mek
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How to look at individual values from a variable in a statistical test

I have this solution which allows me to look at values of my type column individually in a fisher test. (can also swap out fisher for chisq.test) But i tried to apply this to an anova test and had errors. This is my original version # fisher test…
i_love_whiteboards
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Paired t-test for non-normal variable distributed R programming

I want to conduct Paired t-test for 2 variables that one is normal distributed and the other is not (N = 56) I've used the Shapiro-Wilk in order to check normality of the variables and these are the results: Shapiro-Wilk normality test data: …
Ido
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Testing for event clustering with recurring event data, preferably in R

Thanks for all the help you've been over the years. Basically I have a set of data where about 200 individuals were tracked for a number of years and I know when an event occurred during that period. The event can occur more than once for the same…
Christopher Clukay
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Use of Chi-Square Test of Independence

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 groups. Respondents were recruited via…
Amélie V
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