# Questions tagged [group-differences]

Group differences broadly refer to statistics which quantify the differences between two or more subpopulations.

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### Detecting significant changes in groups of values over certain ranges of time-series

Below is an example of data output. It represents indicies [y-axis] calculated for 52 weeks in a range of 64 years. Group of 64 years is classified and several years are represented with blue, some ...
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### T-test for differentially expressed proteins in R?

I hope I am asking to the right place. I am currently analyzing some Mass Spectometry data of 2 mutant phenotypes and the WT with 5 biological replicates each. I have normalized the abundance values ...
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### Pair-wise ANOVA or non-parametric comparison

I'm doing an experiment with 7 groups (batches) of 12 measurements of a certain chemical, where one group (b0) is considered the baseline case. The research question is to find out which groups have ...
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### Statistics to show the differences in population of the sample and city and by sex

Hoping for some help. I am trying to run some statistics for demographics from the results of a survey. I have male/female percentages as a result of the survey (45.1/54.9) compared to male/female ...
370 views

### Comparing sum of values of two groups

I have a question about how to make a comparison between the aggregate values of two experimental groups. Say that in an experiment with a control group and a treatment I collect the number of times ...
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### Is this a matched pairs data set?

A review problem for one of my daughter's statistics classes: The arm span and height of 10 individuals is measured in order to test the hypothesis that arm-span equals height in humans. Perform an ...
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### How do you test if three means significantly differ from each other using an F test?

I know the means, sample sizes, and standard deviations of three samples drawn independently from three populations. I need to test whether they differ significantly from each other using an $F$ ...
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### Survey subgroup difference from entire survey or excluding the subgroup?

I have a survey with categorical (nominal) questions. I want to compare subgroups to see if any are noticeably different from each other. Suppose they are ranking their preferred three from ten ...
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### Comparing statistics over win/loss

I have data from a league over a season. The season was conducted as a round robin so everyone played each other. Each game was a best of 5 so at the least a game produced 3 matches and at the most ...
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### Porbability of an observation to belong to a specific group

I have a group with about 200 observations,and each observation has 2 variables (which are the first two components of PLS, if it matters). It looks like this: ...
125 views

### Find significantly differences between multi-variant groups

I have 11 groups, each consist of about 200 observations, and each observation has 2 variables (which are actually the first two PLS components if it makes any difference). Each group is a substance ...
41 views

### analyzing difference between two groups by other numeric factor with only (0-5) values

I want to analyze the difference between two groups by other factor. the factor is numeric with distribution (0-5) only. using Stata® what would be the best test to estimate the significance of ...
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### Weibull coefficients comparison [closed]

I´ve 838 sets of data that represents points distributed by height. Those that can be fitted by Weibull function. So, I normalized them and adjusted the corresponding distribution function, saving it´...
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### Differences between exponential distribution with very different n sizes

I need to test for the differences between three groups of observations (grouped along $x$-axis), which appear to follow an exponential distribution along the $y$-axis dimension (see example fig.). ...
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### Comparing the results of 2 different type but identical samples from 2 devices

I have 2 columns of of the concentration of fat in fish which is measured by 2 different labs. I need to know if the difference of the results from these 2 labs are statistically significant. The data ...
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### Sample size for 2 groups vs. one large group to measure spread?

I hope this question can simply be answered conceptually, without a specific dataset. I am planning a new study, for which I will be testing the effects of depression on a memory task. I'm currently ...
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### T-test with nested data

I want to test gender differences in an outcome variable called the willingness to pay. My data consists of records with following three fields: ...
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### Which test to use to detect difference in proportion between more than 2 groups? Logistic regression?

I have data that looks like this: there is a group of 27 subjects with one dichotomous variable y1 at 3 times points. The propbability of y1 is different between the 3 time points (100%, 85%, and 40% ...
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### Compare principal components/differences between two groups

I have four groups of individuals which have a certain illness and are part of a clinical trial: Taking drug, illness gets better Taking drug, illness is not getting better Taking placebo, illness ...
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### How to statistically model this group difference?

I am studying if men and women consumers differ in how attractive they find product advertisements written differently. I am specifically looking at positive and negative sentiments as two ...
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### Test if mean of one group is significantly different from means of several other groups [closed]

In my experiment I have a number of clusters of cells from an unsupervised clustering. Each cluster represents a cell type, and can be seen as random samples from a large pool of possible cell types ...
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### Running analyses with uneven group sizes [duplicate]

I was trying to run a study with 100 people per condition for 4 conditions. When I looked at the results, the group sizes were skewed - some had 80, some had 120. If I'm planning on running a series ...
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### Test of difference maximum likelihood parameters SEM R

I have a structural equation model implemented in R 3.4.4 using lavaan 0.6-1 and estimated on two different subgroups using a robust maximum likelihood estimator. Now I want to compare the parameters ...
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### Comparing observed and expected diets of two different species

My data consists of dietary data from two species (C1 and C2) and expected diets for each species (E1, E2) generated from a combination of variables, but is based on their foraging behavior. What I ...
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### Is log based transform comparable across groups with different minimum values?

I have data for different groups that includes positive, negative, and zero values. Here is an example: group1: c(-503583,-395833,0.1,3835,19,-0.001,0,48400883) group2: c(-39,-8340,-10,0,0.1,2889,93,...
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### Difference in distribution of multinomial distributions

I have some questions regarding how to analyse catagorical data, summarised as percentages on an individual level. In the data in question, for each individual we know the fraction of biological ...
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### Combining intra and inter cohort comparison using panel-data

After reading numerous posts, I still haven't found a conclusive answer to my question. I have panel data for the whole population(multiple years, interlinked by personal identification numbers), ...
480 views

### Jonckheere-Terpstra test: two-sided and one-sided, directed and undirected hypotheses

I need to perform a Jonckheere-Terpstra test, but I am not sure how to do it and how to interpret the results. I have following data: Three groups doctors1, doctors2, doctors3 And how often they ask ...
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### Conclusion on which groups differ without doing post-hoc test

If you do a statistical test that compares groups and find a significant difference between groups, can you then conclude that there is a difference between the "lowest" group and the "highest" group, ...
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### Comparison of unbalanced groups of values

I know there are several questions (here and on other websites) regarding the comparison of values, but I am still lost with the data I have and the analyses I should conduct. I have just 18 values (...
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### Comparing groups for hypothesis testing

I have the following analysis to do: what is the relationship of age to blood pressure on overall data. Then, examine the relationship in each subgroup. I have blood pressure readings, continues ...
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### How and when to use multiple comparison tests

There seems to be some variability in WHEN multiple comparison tests such as Bonferroni or FDR might be implemented. Type 1: One might carry out multiple one-way ANOVA's to see whether or not there ...
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### Testing difference in proportions with bootstrap

Summary: I want to perform a bootstrap test on the difference of proportions. I think this is equivalent to testing the difference between means using bootstrap, but I wanted to clarify some details. ...
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### Comparing multinomial logistic coefficients across groups

I have a multinomial logistic regression model - 1 DV with 3 categories and 5 IVs (4 continuous and 1 categorical). I would like to test whether my effects differ between different ethnic groups. Is ...
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### Test for significant differences between groups (in R)

I want to assess whether the differences I find for different groups (of a factor variable) are significantly different from each other. Let's keep it hypothetical and assume a data structure like ...
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### Correlation between different variables and among the group

I'm not a statistician, just a learner and facing problem in my research. I performed experiment on 25 subjects and collected data from 3 different locations (muscles, say A, B, C). The experiment ...
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### What statistics to use and How for “difference in differences”

There may be similar questions posted earlier but I am a novice for statistics and cannot discern them from mine, so I am posting my question as it is. What statistics can I use and how to use it (...
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### Creating better groups

I have a number of groups from which I need to select next groups with same number of members. Each member has a certain number of features (metrics). New groups should be selected so that one of the ...
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### Correlational Meta-analysis

I conducted a correlational meta-analysis. There were three groups of behaviours and one aggregate effect size for the correlation between each behaviour group and a continuous measure. We used ...
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### How to reduce sample data to a smaller scale?

In statistics let's say for a specific city (call it "City A") 1000 people die of driving related accidents annually. The city has a population of 2.7 million people. In another city, "City B" 3000 ...
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### Statistical test for differences in counts between groups

Goal: Test if there is a statistical difference between Tue and the rest of days of the week. Background: I wanted to use ...
240 views

### Difference in means statistical test for non-normal, heteroscedastic data?

Suppose I have a data set with three or more groups. After some exploratory data analysis, I find that The groups do not come from a normal distribution the variances within the groups are not equal,...
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### Simple question about difference of two proportions testing

It is usually explained in biostatistics textbooks that to do a z-test for the difference of two proportions, it is necessary that p*n and (1-p)*n are both equal to or above five for both samples. ...
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### Testing for statistically significant difference between two groups

I have data of 8 temperature points inside and 8 temperature points outside a city. What is the correct way to test whether there is a significant difference between the two groups of data? ...