# Questions tagged [group-differences]

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

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52 views

### Assess statistical differences between groups

I have a list of percentages of words per group, something like: ...
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### Large sample - statistical significance with minimal differences [duplicate]

Small disclosure I am doing a course that requires learning statistics but it is not my field of expertise so I may make several mistakes, apologies in advance. Also, I will add some background as ...
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### Testing differences between samples vs. population

To my knowledge, established tests such as ANOVA are testing the differences between the "underlying population" of sample groups, implying the sample is a representative of something bigger....
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### How to decide between individual versus group level random effect

I have N participants each has inconsistent number of repeated measurements of an outcome Y. Each participant belongs to one of two groups. My hypothesis is that the levels of Y differ significantly ...
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### How would you test for a difference in mean group differences between scenarios?

Suppose I'm looking at gender differences across two scenarios (all respondents answered both scenarios) and I want to know whether the gap between men and women varies between scenarios. Suppose the &...
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### Which analysis to use for nominal (binary) dependent variable with multiple IVs of various types?

I have 1 dependent variable (DV) measured in binary (Exam, pass/fail), 3 independent variables (IV-1 is continuous (age, in years), IV-2 is binary (Country, Canada vs. US), and IV-3 is nominal, but ...
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### Which statistical model to choose in order to overcome the multiple testing problem in grouped data of two groups?

I have a data set with the following structure: Group_variable;Position1;Position2;Position3;etc Each Position column holds ...
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### Confidence interval not including the actual difference of the means

I have used statsmodel in python to compare the means between a control and test group. The difference of the means is 29 and I get a low p-value making my results statistically significant. The 95% ...
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### What is the best method to compare two populations within a bigger group?

I have a data frame with two columns: rows correspond to different people, one column is the country of the respondent. This is a categorical variable, the other column is the yes/no answer to the ...
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### Is this correct use of linear mixed model?

This is the current data I have I want to know if fixed factor A has any effect on C. That is, if A1 = A2 = ... = A5. I think I am trying to find a group difference, correct me if I am wrong. ...
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### Comparing n sample means

To preface, I'm a stat noob programmer, so sorry if this is a basic question. I have multiple (300+) exams that I had a variety of users take. The users could decide which exams to take. All the exams ...
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### What statistical test to use for comparing result between two treatment types

I want to study the difference in inflammatory response in subjects receiving the drug Pioglitazone versus placebo measured as plasma hsCRP level (a continuous value). I also want to adjust this with ...
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### Conjugate Bayes versus MCMC for comparison of two proportions

I want to compare the posterior risk distribution in two subgroups of the same dataset. I was wondering if compare samples from the conjugate posteriors built independently on the two groups would be ...
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### Statistical test to determine if a variable is significantly positive or significantly negative?

Is there is a single statistical test I could do that would allow me to determine if a variable is significantly positive or significantly negative? By significantly positive or negative, I mean that ...
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### Isolating causal effect

we are going to have kids working together. So for example, there could be 20 groups of 3 students each. What we would be interested in seeing is if the presence of particular students affects the ...
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### Treatment effect by regression slope in simulated A/A-test

Sometimes when doing A/B-test, I see a difference between control and test groups before experiment. I want to decide whether or not subtract this diff from the diff after the experiment (diff-in-diff)...
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### Clarification of methods for using non-parametric tests to compare groups- vegan package

I would like to validate my approach to comparing groups using non-parametric tests. data created below describes the structure of my data. Each ...
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### Multivariate time series vs panel data vs?

Apologies for the clunky question, I'm just looking for recommendations for the type of model I should be looking into. I can do the research from there, I just don't even know what to look up at the ...
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### Is there a meaningful way to combine relative and absolute difference?

I have two datasets for two different scenarios in the same study area. To clarify, it is the origin and destination of trips - split up in different zones. Therefore zone 1 has x-many origins and y-...
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### Standard error of difference in means: Adding variances vs. doubling the pooled variance

My question concerns the use of two different formulas to calculate the variance/standard error for a difference in means, as for example needed for a t-test. The textbook formula for the variance of ...
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### Which test to use? Independent data or not?

What I have is a cross section of a bone divided in 60 equal slices. These 60 slices form 4 groups of 15 slices each corresponding to the 4 anatomical orientations (anterior, lateral, posterior and ...
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### Sem with groups

My purpose is to test the same SEM model on two independent groups. However, some of the variables that participate in the model have significantly different values between the two groups (e.g. age is ...
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### Suitable panel data method for regression

I am working on a project where I want to predict the GPA of students in the $k$th semester based on their GPAs in the last $(k-1)$ semesters. I have a data of 200 students from 2 batches of a 6 ...
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### Measure degree of separation between two groups

I have a gene matrix with many columns and would like to measure the "degree of separation" between pre- and post-visits for each variable. I've been using log fold change but this method falls apart ...
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### Independent Samples Test with one Group Zero Variance

I am not sure which is the right test for my data: I want to compare two independent groups n=10 vs. 8, the data is absolute scale and not normally distributed. Normally I would use the wilcoxon test ...
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### A method to separate classes while taking variable dependence into account

I have posted a question related to this problem over a year ago and we still were not able to figure this out. We have two groups, A and B that we want to train on to separate them. Both have ...
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### Correct group definition and ANOVA test application

I have a dataset with multiple (n=140) repeats of simulations run under the same conditions, however, there is a source of variability in the model. I would like to ...
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### What's the standard error of a proportion where there are multiple groups?

If I have a sample with groups x, y, z, where there are 300 of x, 600 of y, and ...
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### Cohens d effect size calculations across 3 groups

Is it possible to calculate a single Cohens d effect size, across 3 groups? I have successfully used Cohens d to calculate the effect sizes between state 1 and 2 (as simple example given below) for ...
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### testing significance between more than 2 groups with Standard Error in values ( American Community Survey)

The American Community Survey (ACS) provides estimates for socio-economic variables across USA, with different spatial resolutions (County, Zip Code, Centus Tract...). For each variable and each ...
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### Is two way ANOVA with repetation the approach here?

I have a dataset from a survey. The survey consists of 20 people who were shown two versions of an advertisement on TV. After each version of viewing, the respondent was asked six questions about the ...
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### Performing t-test for coefficients using bootstrap

I am having some difficulties reconciling a test for the difference in means using a standard test and the bootstrap. It would be great if someone could tell me what is going wrong in the code. I run ...
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### Which test to use when comparing two variables of which one has multiple levels?

Here's some example data: ...
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### Difference between using an interaction term for categorical predictors vs. creating subgroups (linear regression)

In a linear regression with two categorical predictor variables: Let's say the most simple case (e.g. 0= male, 1=female; 0= no vegetarian, 1= vegetarian), so based on those two nominal variable a ...
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### is it possible to test the difference of the difference between means in a linear model with interactions?

Data I am working in R and I have continuous data identified by two factors: class and subclass ...
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### Statistical test for grouped results without individual data

I have a dataset containing grouped participant ratings for words. Several groups of participants rated the words, these groups differed in their age and sex. However, I do not have individual ratings,...
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### Group comparison for linear regression?

I am analysing data and was wondering which analysis to use. I have two groups of participants which received two different kind of treatments (trt1, trt2). There were two times of testing (time 1, ...
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### Compare medians between two groups without the raw data

I have to compare a couple of groups. I have the median, mean, 1st quartile, 3rd quartile and size of both samples, nothing less, nothing more, and no further info about the two groups. Is there a way ...
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### Degree of freedom/sample size of a combined quantity calculated from several individual estimates?

Say I have data for CO2, CH4 and N2O emission in my experiment (having different experimental treatments). Each treatment means of either CO2, CH4 & N2O are calculated from 4 replicates (4 pieces ...
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### Bootstrap hypothesis test for median of differences

I have not found any examples of bootstrap hypothesis tests for the median of differences. Hence, I'd like to suggest my approach. Question: Do you a agree that the reproducible example below would be ...
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### Hypothesis testing for difference in medians vs. median difference

I found this post saying that one should test for the median difference instead of the difference in medians, in particular if the data is skewed: http://onbiostatistics.blogspot.com/2015/12/median-of-...
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### How can I find the difference in features between two groups?

Assuming I have 2 data sets with 200 features each, and I can tell there is a difference between the groups in behavior. I want to identify the difference between these two groups (what features are ...
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### Using PCA output as part of further analysis through GLMM or t-tests

I have a data set with 11 columns: one column for ID, one for Sex and one for the number of test (1-4) with the rest of the variables being numeric. I ran my PCA's and was able to generate graphs to ...
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### Can we use permutation test everywhere to check difference when the null hypothesis is “there is no difference between two groups of data?”

What I am trying to do? Let's assume, I am working on a research problem where only one participant is present. I have a data set consisting that participant's respiration rate (The number of breaths ...
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### How to find the difference between two set of scores of a single participant?

What I am trying to do? I have a data set which consists of only one undergraduate student's all courses scores. Let's assume, he has completed about 70 courses where 40 courses are related to ...
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### Are my samples independent and therefore suitable for a Mann-Whitney U test?

My data has the following structure: ...
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### Propierty of reporting multiple types of effect size in one research

Right now I'm conducting a research based on two sample independent tests. I want to report effect sizes along with test's p-values. However I became hesitant as each effect size equation comes with ...