# Questions tagged [group-differences]

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

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### How to statistically treat my data?

Here's the situation. I have 3 set-ups: A, B, and C I want to measure 2 variables in all of them (pH and alcoholic content) over time I want to know if the pH level or alcoholic content in A is ...
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### How to compare the difference of two time points of two groups

Let's say I want to compare the height change of female students and male students between two time points. I want to know if there is any difference between males and females in terms of the height ...
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### Bootstrap-based robustness of a test checking. Is resampling from sample distribution a good procedure?

I aim to check the robustness of 2 groups t-test when samples come from lightly skewed distributions. To approach the problem I though about performing a Montecarlo based robustness analysis using ...
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### Can the chi-square statistic in Kruskal-Wallis test be compared to determine the most appropriate to distinguish the groups?

I have a dataframe in R which format is similar as follows: v1 v2 v3 group 1 3.5 100 a 3 5 200 a 10 5.5 150 b 8 7.5 210 b 4 4.5 300 c 9 2.5 200 c ... My ...
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### Logistic regression - One model trained on different groups

I have a logistic regression model that trains a set of binary independent variables (X) on a binary response variable (Y). The data was gathered from different individuals for who also e.g. socio-...
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1 vote
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### Calculate the difference and identify the type of change between levels of a factor

I have a data set with the following structure: ...
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### Statistical methods for different parts of a distribution

I have a distribution of discrete values (grades, from low to high) where I see that the certain groups have a higher frequency of observations in the higher ranges and less in the lower ranges than ...
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### How to compare subjects/groups with multiple variables which have multiple values?

I would like to get an opinion about comparing groups of subjects that have multiple variables multiple times. I have three groups (A,B,C) divided by their age. Each group has a different number of ...
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### R statistical test for two groups with three categorial variables [duplicate]

I have two groups, in which three possible outcomes appeared at different frequencies, and I wanna know, if there is a significant difference in-between the groups. For instance, I have two potatoe ...
1 vote
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### Two Samples Test for Discrete Variable and Different Size Groups?

Hello there and apologies for my English and lack of statistic skills! Two different groups of participants, one comprised of children and the other of adults, run once, at different times, the same ...
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### How to compare before and after evolutions of a binary variable between two groups of treatment

Here is what look like my data ...
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### Anosim vs Permanova: What are their suitability when computing differences between groups?

I am back with more questions, this time about multivariate analysis. As before I am new to this all so apologies in advance if the question is not well formulated. The problem We are trying to ...
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1 vote
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### What pre-/post-treatment cohorts should I include in a generalised diff-in-diff with treatment on cohort level?

I analyse an educational policy that shortened mandatory schooling. The rollout of the reform happened over 3 subsequent years in different states ($c=0$ is the last graduation cohort pre-reform, $c=3$...
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1 vote
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### Testing for difference in means between two groups for which each measurement has a unique associated uncertainty

I am wondering what type of statistical test would be appropriate to test for a difference in means between two groups for which each measurement has a different uncertainty. For example, I want to ...
32 views

### Hypothesis Testing of Absolute Difference

Is a one-tailed hypothesis test of $|S_1- S_2| = 0$ equivalent to a two-tailed hypothesis test of $S_1 = S_2$? ($S_1$ and $S_2$ obviously represent a certain statistic of two samples.) If not, where ...
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### I’m trying to find the association between 2 variables by conducting a statistical test

My two variables are sex (male/female) and body mass index (BMI). I have a data set of 194 participants. Sex - 107 males (55.15%) / 87 females (44.85%) BMI - 23.88 +/- 5.03 I have no idea which test ...
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### Test for multiple groups with cumulative data

I'm new in R and I'm doing research about the differences In germination rate between rare and common sister taxa. I planted the seeds counted each day how many of them germinated. I used the cox ...
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### Comparing for differences between groups of participants

I recruited participants from two different places as I was struggling to get enough people. The two groups are very similar in terms of background etc. However, I was told I should compare these two ...
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### How to decompose total slope into between-group and within-group contributions?

Consider the following data (I put the data as a table in the bottom of this question.) These data are in two groups, blue and orange. In each group there is a positive relationship, while pooling ...
1 vote
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### How to adjust for the baseline difference between groups for a histogram

I have data from an experiment that tested responses to stimuli in females and males. I measured baseline for both groups prior to presenting the stimuli. The baseline for males is higher than for ...
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### get CI bands on predicted fit from nls/nlme(r) models in R with subscripted parameters

I have a dataset with different groups (bacterial strains) with a continuous response variable result to which I want to fit a non linear model. Initially, the parameters of this model need to be ...
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### Unbalanced control and experiment group sample size

I am working on testing the significance of a training program for businesses. We offer the training to the experimental group and want to compare some metrics to the control group. Because it takes ...
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### Measuring within-group similarity for ranked list responses

Individuals are completing a task in which they rank 15 items (1-15 according to importance). These individuals will later be working in groups of 4, so I am interested in measuring the similarity of ...
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70 views

### Equal Variance vs. unequal Variance for comparing Groups

I am a little bit confused about equal and unequal variances. I understand the definition and mathematics behind it, yet I don't know, for the purpose of my research, how to appropriately test that. ...
1 vote
158 views

### test of significance for two groups of classification results

I will edit this question for more specific questions. I want to predict the presence of multiple, binary questionnaire items with a classifier, such as SVM. I do this via 10 fold nested cross ...
1 vote
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### Need the equivalent of a "paired T-test" for percentages (test-retest comparison between groups)

I have an observational study with a control group and a treatment group (n=25). All the subjects are given the same test (which consists of 9 questions, each of which has 4 multiple choice answers). ...
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### Comparing variance explained by regression model across different age groups

I'm interested in whether the variance explained by a regression model (i.e., R2) differs between age groups. I have run the same regression model in four groups of different ages and have obtained R2 ...
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### How to fit a mixed model with a skew normal distribution in python?

I am not sure if this is the best place to ask this so if not, please let me know, however I am using StatsModels to create a mixed effects model that assesses the ...
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### Examining growth rates and sex differences

I'm trying to figure out the best statistical test to use to understand my data. I've searched but haven't found anything super applicable. I'm working with an endangered animal species and have a lot ...
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### Fitting two lines to convoluted data [duplicate]

Assume you are provided with data derived from two linear equations + noise, such as that below. How would you go about deconvoluting the lines, and obtaining their slopes/biases? Colab link for ...
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### Showng distinct clusters/groups in microbial community data and accounting for different number of replicates?

I have 16S data to look at the microbial communities of two types of hot springs; I've been working with this in R. Some of the data is from 2017-2019, but the bulk of the data is from last year. ...
1 vote
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### Testing difference of medians and stochastic ordering using paired samples

I have paired samples from skewed distributions with unequal variance (before and after treatment), and would like to test for difference of means difference of medians stochastic ordering of treated ...
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### Statistical test to test differences between 2 categorical variables

I have a data set outline preferences for 3 groups of subjects regarding payments and game features. The set looks like this: payment_source_preference favorite_feature Group GroupSize NoPreference ...
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### What are the steps for making comparisons by group?

I have a question about the need to combine data when making comparisons between groups/levels of different factors. My dataset contains columns associated with the time and location it was collected (...
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1 vote
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### Sample size for a comparison of means based on rates

In a clinical trial, I want to demonstrate an effect following an intervention between two groups. The outcome variable is the rate of improvement. That is, the patient may experience an improvement (...
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### group differences means and standard deviation

The mean and standard deviation of the mass of owls in group 1 is 3.124(3.806) kg. The mean and standard deviation of the mass of owls in group2 is 6.295(4.015) kg. Can I say that although the mean 6....
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### What is the best way to compare changes between two groups?

Given we have two equal-sized groups, each with a continuous pre and post-measure. E.g., in an RCT with a treatment and a placebo group and a pre and post-intervention outcome measure, and no drop-out....
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### Defining Timespan to Define Churn

I have this dataset containing list of customers and their last transaction date. I'm planning to group them based on recency data: how recent are their last transaction? I would like to have three ...
1 vote
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### Anova models: different parametrizations give different results

In class our teacher explained that there are different parametrization which can be used to make the design matrix called CornerPoint parametrization: the first coefficient represents the mean value ...
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### percentage of difference with estimated marginal means

I am calculating the difference between concentration of different metabolites according to the factor sex (male/female) and age group (<55 / >=55) from this linear model: ...
1 vote
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### How can I test if there are significant differences between four distributions?

Here is a graphical display of my data: The x-axis is categorical from 0-5 in terms of how many of a certain damage type are present on a leaf (with pink and blue bars representing the different ...
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### Testing difference in coefficients for two treatment conditions in separate models with shared control group

Subjects were randomized into treatment and control groups. Within the treatment group, subjects were randomized to receive the treatment under condition A or B (mutually exclusive groups). For all ...
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1 vote
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### How do you calculate a confidence interval for the difference between 2 dummy variables?

I think I understand how to calculate the confidence interval for the difference in means of 2 groups when there's one dummy variable. You just add or substract 1.96 x (the standard error of the dummy ...
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### effect size (group difference) with within-person and between-person distances

Is there an effect size measure to quantify the difference between within-person and between-person distances? Note that this is different than within-group / between-group designs, since there are ...
• 135
16 views

### Sample Group Mean Difference and Central Limit Theorem

Suppose that there is a binary treatment variable: $$D_i=\begin{cases}1 \qquad \textrm{if}\quad \textrm{an individual i takes a treatment} \\ 0 \qquad \textrm{otherwise}\end{cases}$$ Let $Y_i^1$ and \$...
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### Can you run a hypothesis test for difference between means when all you have is the mean and size of each group?

I know an ANOVA test can be used to test for difference between means given the sample, mean, and SD for each group. What if you're missing the standard deviation, though? Can any hypothesis testing ...
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### Determine if two groups differ for a series of binary variables - logistic regression

I am trying to determine how to analyze my dataset. I have two stimulus categories (Type 1 and Type 2) and then a series of variable observations that are binary (did respond/didn't respond, did ...
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### Comparing internal to external variability of clustered datasets

I have 1500 datasets, divided between three groups. These datasets are collections of pairs (data, weight) where both data and weights can take any positive real value. The number of elements each ...
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