Questions tagged [group-differences]
Group differences broadly refer to statistics which quantify the differences between two or more subpopulations.
677 questions
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How to retrieve main group effects from GEE in R (anova?)
I want to know if the outcome variable differs across three groups. As my data includes several family members, I use a Generalized estimating equations (GEE) model in R:
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Why is a pooled mean necessary in bootstrapping the difference in means?
Formulated Question
In a two-sample bootstrap procedure for testing the difference in means, why is it insufficient to subtract the group-specific mean from each bootstrapped observation (centering ...
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Unsure as to what tests, how, and potential in a research scenario
There are three classrooms of students of different grades. I want to analyze what variables of these influenced likelihood of scoring 0 on a test. The factors are: grade (8, 9 or 10) and stress level ...
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What are the advantages and disadvantages of using a one-way between subjects MANOVA versus a split-plot repeated measures ANOVA?
For example, I would like to analyse the difference in heart rate, breathing rate, height, weight, and number of hair between three species (cats, dogs, and rats). This is a nonsensical example of ...
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Modeling disease vs. microbiome: which should be the outcome?
I have a question related to microbiome research, an area where many researchers assess whether taxa abundances differ between disease and control groups. I often see statistical models where taxa ...
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2 Between-subjects, and 2 Within-subjects, and 2 DV
My data contains the following characteristics:
Between-subjects factor: Group (Intervention A vs. Intervention B)
Within-subjects factor: Time (Pre vs. Post)
Dependent variables: Anxiety (Scale A) ...
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Comparing correlations for two variables in different overlapping groups
I have a sample where I have applied five (wildly differing) diagnostic definitions for the same disease. For example, 50% of people who are disease cases under diagnostic definition 1 are not disease ...
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How to calculate and compare the apparent likelihood of an interaction between groups of different sizes
I need to compare variation in virus transmission within and between three differnt sized age groups: children (N= 20,000), adults (N= 60,000) and older people (N=20,000). So, within the population, ...
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Evaluation Metrics for Item-Focused Tree in Identification of Differential Item Functioning in a Real-World Data
I am working on a real-world data set comprising patient-reported outcome measures. I will apply LASSO and item-focused tree (IFT) (some machine-learning methods with Logistic regression underlying ...
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Test between model output over a binary variable
I have a set of features that includes a binary variable (called $B$) and some others ( binary or numerical variables, let's these covariates $X$).
I have a target variable that can be either binary ...
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How to compare two non linear model fits
I am working with two datasets containing leaf parameters (gas exchange, temperature, and humidity). Each dataset is from a sampling site. I have used an NLS model to fit the gas exchange using ...
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How to differentiate the grouping effect and the random effect when fitting GAM model?
according to the definition:
The Hierarchical Generalized Additive Model (HGAM) allows modeling of nonlinear functional relationships between covariates and outcomes where the shape of the function ...
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How do I test whether an independent variable influences variable A but not variable B, taking into account my stimulus replication?
I have a mixed design that includes a two-level between-subjects factor and a repeated measures variable with four levels. The repeated measures variable represents a stimulus replication, meaning I ...
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Testing whether mean sample difference between two groups is different in two different samples
Suppose in a medical study there are the following students recruited to the study:
300 Japanese males, 500 Japanese females
600 Australian males, 700 Australian females
The particular study is about ...
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How do we deal with confidence intervals containing values that are consistent with both the null and alternative hypothesis?
For instance, assume that when testing for a significant difference in means of some measure between a control and a treatment group, I observe a difference in means of 0.5, suggesting the treatment ...
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Does Bayesian ANOVA analyze variance?
Does Bayesian ANOVA involve any analysis of variance?
In classical/frequentist ANOVAs, two different unbiased (assuming the null hypothesis) estimators of the variance are compared. That's where the ...
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ANOVA with unreliable measure
I’m doing some literature review on sports science, in particular the effect of training on endurance.
There is no standard endurance tests. Some consist in intermittent contractions until exhaustion ...
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test for differences in empirical cumulative distribution functions between groups
What test could I use to test for differences in empirical cumulative distribution functions between two or more groups? Note that I am not looking for a test two compare two ecdf (Kolmogorov–Smirnov ...
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Measurement invariance across groups and time
I want to run a multi-group longitudinal model. Based on prior invariance testing, I can assume scalar invariance across groups and time. So is it appropriate to have both the same intercepts across ...
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How to find difference between two hazard ratios (ratio of hazard ratios)
I am reading a meta-analysis and in this paper the authors somehow compared HR from two groups with different treatments in each study. As I know, we can compare outcomes from two groups with ...
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What is the best t-test to compare two groups with a confounding factor and unequal sample size in each group?
I am working on my master thesis and came up with a problem. I want to validate if changing the raw material for a chemical reaction would give the same yield of my product of interest. First, I did ...
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Fitting multiple linear regression models to select molecules for which a feature of interest significantly alters concentration
I'm using data from a proteomics platform called Olink. In this case, the data comes from samples of 16 patients and 16 controls. The patients can be further classified into 2 subgroups. The assay ...
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How to properly compare a single diagnostic test in two subpopulations
Suppose I have a diagnostic test with a binary response. I have performed this test on some population.
Now, I split this population in two subgroups (e.g. male/female), and would like to check if ...
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gene total volume test
1, I want to compare the FGF gene total expression level (sum level from all the cells) in two groups of cells. Suppose group A has 500 cells and group B has 100 cells.
2, gene FGF level in the two ...
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Appropriate Research Design for Multiple Independent Variables and Dependent Variables
I need some advice on designing the quantitative aspect of my upcoming master's research project. My research design involves a convergent mixed methods study and aims to explore the factors that ...
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How to analyze between-group differences in within-group variances over time in a 3-level model?
The data I am using is collected within the physical fitness surveillance program in schools. In these schools, either no intervention, healthy lifestyle intervention, healthy schools network ...
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Standardization of summary statistic of group-linked values
Assume that you measure a summary statistic (e.g., arithmetic mean) in measurement windows of a fixed size along a long sequence of values and that these values are grouped into regions belonging to ...
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ANCOVA or MODERATION?
I'm struggling with the statistics for a question I'm collecting data to answer.
My paper is about whether different meditation types can increase happiness when controlling for meaning in life. There ...
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Group comparison with multiple group memberships
I want to statistically compare personality scores between different groups, but people can be in multiple groups. Is there anything problematic in just doing an ANOVA or a t-test since a respondent ...
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Transforming data with two groups for multiple regression analysis
I have a dataset includes 2 groups (HC, PT) and unfortunately, variables (8) are not normal. I'm trying to run a multiple regression to see if the relationship between the variable of interest ("...
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Variability of patients in different Hospitals
just to let you know that my statistical background is not very good. I made funnel graphs which shows the effect of polypharmacy against practice size.
In the funnel graphs, a dot presents a single ...
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What is the difference between a one sample t test of the difference between two groups versus a two sample t test comparing the two groups?
Let us say that we currently have two independent groups $G_1, G_2$ with equal sample numbers $n_{G_1} = n_{G_2}$ and may not have equal variances $ {\sigma_1}^2 \neq {\sigma_2}^2$. If the statistical ...
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How to compare frequencies of type of stress events with repeated measurements over time in a weekly diary study?
We hope you can help clarify whether a Chi-square test of equal frequencies (in SPSS) would be the correct choice.
Study participants have reported experienced stress events (text variable) in a ...
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Data analysis for school project
I have to create a hypothetical study focusing on the relationship between sBCMA (soluble B-cell maturation antigen in blood) and the expression of BCMA on bone marrow cells in patients with multiple ...
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Best statistical approach for determining a significant cutoff value?
Assume a study comparing fingernail length to incidence of fungal infection. Ultimately, the goal is to determine a maximum length to propose for use by animal care takers.
One proposed approach: 1st ...
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How to calculate bias having three groups?
Three groups of people each tried one of the three different applications and answered a questionnaire on a Likert scale from 0 to 4. Their age and experience in video games were also asked (on a ...
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Which test do I need for testing differences in two populations?
I would like to compare the different variables in a life table of two populations and check if the differences are significant. However, I am totally unsure which test is appropriate.
For example, I ...
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DiD with multiple overlapping windows
I would like to set up a difference in difference model with multiple overlapping windows. The treatment group are firms located in a county hit by a hurricane while the control group includes all ...
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Is there a meaningful way to 'quantify' a group representative partition of its network when subjects within group have their own unique partitions?
I currently have a dataset which can be split into two groups: disease vs control. Each group consists of $n_{disease}$ and $n_{control}$ subjects respectively. The dataset itself is a correlation ...
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Identifying an outlier nominal group different than the norm, based on an ordinal dependent variable
As part of my graduate thesis, I've measured the satisfaction levels of a couple hundred respondents across 7 districts of a city about a local public service, using a 4-point ordinal Likert scale (...
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What is a good measure of the effect size of group difference in a multigroup multilevel model?
Consider that you have a multilevel model measuring students' mathematics knowledge. The students are nested within classes, and classes are nested within schools. Additionally, we want to examine the ...
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Can I aggregate several continuous variables into percentages and then compare those percentages between groups?
I have a dataset with the concentrations of several lipids. I'm interested in finding lipids that are altered between two conditions, but the lipids are not indepentent from each other and the ...
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How do I interpret low subgroup interaction and high efficacy in only one group?
I have read several articles concerning subgroup interaction interpretation but none of them have the situation I am dealing with. Suppose we have an experiment with a control vs treatment influence ...
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Is it valid to use unsupervised clustering to assign patients into larger groups before comparing them to controls?
I have very high-dimensional data (lipidomics) with two categories: patient/control and genetic mutation. These mutations have similar phenotypes, but they are considered different diseases. Their ...
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what book should I read to learn inferential statistics? [closed]
I am not a statistics student so I have no clue about inferential statistics. All I learned was descriptive stats. I am currently conducting research to find if two groups are similar/not. I have ...
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How to code for a mulitgroup analysis concerning two catagorical variables
I have a question on syntax for Mplus.
I am running a multivariate latent growth curve with 7 repeated measures, variables X and Y (diagram attached). I also have two grouping variables, sex and ...
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Effective pairwise comparisons for group ranking?
Suppose I have a list of items(~3500 in number) and I want to do a group based ranking into 4-5 groups. I can get pairwise comparisons between the elements but I want to choose the items to compare in ...
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Which test would I use in this situation?
I have a sample of people, $n=300$. All $300$ should be offered both of two therapeutic treatments (Treatment A and B). I will be collecting data on how many people were offered A only, B only, and A ...
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Comparing the pattern of commensal of two drugs over time
I would naturally appreciate your advice on the following problem:
Following operations, patients can be started either Drug A or Drug B to prevent blood clots forming in patients calves. We surveyed $...
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One-way repeated measures ANOVA with skewed response
We have an experiment with 102 individuals in total. We have an outcome $Y$ (which is a variable related to the structure of a given bone), and we want to know whether this variable $Y$ differs ...
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