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

learn more… | top users | synonyms

1
vote
0answers
5 views

Comparing Performance and Determining Scaling

My understanding of statistics is fairly basic, but I'll try to be precise here. Method X of doing something exists and can be timed with a particular method of ...
0
votes
1answer
26 views

Grouping usernames/emails in a data set

I have a column in a dataset that is the 'user'. Can look like this: tom green tgreen tomgreen@here.com sam blue samtha green How do i get this to group this so that the first three are grouped ...
0
votes
0answers
4 views

Compare related time-series count data before and after intervention

For a university library we did an intervention to create more free seating spots for students by introducing a way for students to temporarily give up their spot while away. They did this with an ...
0
votes
0answers
15 views

What statistical test should I use to compare the binary outcome of two groups (with pre- and post- test)?

I have two groups of people: experiment group and control group. People in each group accepted pre-test and post-test. The outcome of the tests is binary: "good" or "bad". In other words, each people ...
1
vote
1answer
24 views

ANOVA (assuming different distributions) vs Kruskall-Wallis and post-hoc tests

During stats courses on Uni I learnt (if I remember correctly and hopefully don't put my teachers to shame) that if you want to compare multiple groups with eachother you look at the residuals of an ...
0
votes
1answer
23 views

Estimate group averages

If I have 100 numbers from two separate groups $X$ and $Y$. How can I manually estimate or derive an algorithm to automatically estimate $AVG(X)$ and $AVG(Y)$? I know all the numbers, but I don't ...
0
votes
2answers
24 views

Cluster two feature samples with no knowledge of the number of clusters

Thanks in advance for the help I have around 13000 samples with two features each and I would like to cluster these samples into groups. A few caveats. One, I don't know how many groups there are ...
1
vote
1answer
9 views

Standard effect size for assuming equal means

I do a community survey on a website once each year, I have data from the past two years and this year I'd like to remove questions which are getting similar answers each year. The survey questions ...
3
votes
1answer
49 views

T-tests, manova or logistic regression - how to compare two groups?

I'd like to check whether women and men differ on those five variables, that can be correlated with each other. The groups are also not equal with 589 females and 293 males. The solutions that come ...
0
votes
0answers
41 views

Plotting many groups tested with many experiments

I have 1 control group and 9 treatment groups. The 10 groups are tested against 13 treatments (with each have 3 variations so a total of 39) and results are collected. How to plot the results in as ...
1
vote
1answer
22 views

Conditions for groups in independent samples test

I wish to conduct an experiment where I have a number of different groups, let's say four groups of X people each. Each person in each group partakes in a similar experiment, with each group testing a ...
3
votes
2answers
59 views

How to interpret Mann-Whitney's statistical significance if median is equal?

Testing the difference between the observations of two groups by using Mann-Whitney Test has given the following output (from minitab): ...
3
votes
1answer
42 views

Principal component analysis with group data

In my experiment I have used 30 different accessions of a species. One group is challenged drought and the other group is control. I have collected data on 6 different parameters. I want to know which ...
0
votes
0answers
13 views

How to assess difference between two groups

I am a newbie in analysis of transcriptomic data and I've encountered some problems. I have a data set, where are two groups of samples (7-8 samples in each group). I would like to define if there is ...
0
votes
0answers
13 views

How to analyze whether there are significant differences between 2 groups in samples (with 4 characteristics)?

I am stuck in analyzing my own data for my bachelor's tesis. I have 1 IV,1 DV, 1 mediating variable and 2 moderating variable (all items used Likert Scale), and 4 control variable which are Tenure, ...
1
vote
0answers
38 views

MANOVA or Mixed ANOVA? Several measures as dependent

I am trying to analyse data of 2 different groups (control vs experimental, brain damage) and their performance on 3 different cognitive tests (the results of which are not correlated) to determine ...
0
votes
0answers
6 views

Integral formula for differences in means between groups

BACKGROUND: I was fascinated by the discussion on this post discussing the issue of interpreting the meaning of confidence intervals versus credible intervals, as well as their calculations. In an ...
0
votes
1answer
45 views

Is it possible to normalize data by different group leaders separately?

I have a dataset that contains different states of a country. In every state there are different companies and one company in every state is manager of other companies in that state (other companies ...
16
votes
5answers
1k views

What is effect size… and why is it even useful?

I have an introductory-graduate-level statistics background (assume I know mathematical statistics and probability at an undergraduate level (e.g., Wackerly et al., Ross' Probability), and have some ...
0
votes
1answer
38 views

Compare t-test of difference in means of 3 samples

I am comparing the statistical significance of the difference in means (say average age) using three samples (say classes) a, b, and c. The results of t-test show that there is no significant ...
1
vote
0answers
69 views

how do I compare percentages and show they are significantly different?

Here is my data: I have two groups (experimental group and control group)voting for 6 different actions, listed as A, B, C, D, E, F. The sample size of the 2 groups are different. Therefore, I am ...
0
votes
0answers
11 views

Within-Group differences, small sample size

Let´s assume that I have 10 groups with 10 participants each. Each participant had to rate a couple of different topics on a likert scale. I have the hypothesis, that the participants within each ...
1
vote
0answers
70 views

Statistical differences between two hourly patterns

I have 2 groups of subjects, namely: Subjects that are younger than 67 Subjects that are older than 67 Each subject of each group wears a sensor that estimate the metabolic equivalent of tasks ...
0
votes
1answer
18 views

Testing for significant differences in populations from one sample

I have a data set with population information for 6 age groups. In theory, I wish to know if a specific two of these age groups are different from each other. My first question is: Can I subset the ...
0
votes
0answers
31 views

Which statistical model/method should I use?

I have a data collected in New Jersey, and the units are individuals nested in four cities. Within four cities, there are also three types of neighborhoods defined by someone. I am trying to see if ...
0
votes
1answer
19 views

Repeated-measures while comparing groups

I've been reading up on related posts, however I'm still confused as to how to choose the appropriate test to analyse a repeated measures variable, while also comparing two groups. The situation is ...
2
votes
1answer
54 views

Mann-Whitney with many zeros

I'm running a basic Mann-Whithney U test in R between two groups; each group represents the abundance values of a particular bacteria within an animal. Therefore a 0 means that bacteria is not ...
0
votes
1answer
22 views

correct statistic method

I would like to ask about correct statistic method. We did an observation of wild population animals in a specific place. We observed that species tend to group differently. We created a 5 size ...
0
votes
1answer
23 views

determining effect of disinfectants on microbes at varied pH levels

I did an lab experiment to determine effect of 2 disinfectants(chlorine,prep) on 3 test organisms(albicans, salmonela, s.aureus) in view of time the organisms take to be killed. the disinfectants are ...
4
votes
1answer
163 views

Approaches to compare differences in means with differences in proportions?

I have summaries of hundreds of variables for two populations. Most of these variables are counts, but some are continuous. For example, if I had population sizes $N_0 = 20000$ people and $N_1 = ...
2
votes
0answers
59 views

Comparing unbalanced groups (One group has only 1 observation)

I would like to compare a continuous variable across 5 health status groups, but one of the groups has only 1 observation. Would an ANOVA/Kruskal-Wallis be valid? What can I do about the group with ...
0
votes
0answers
23 views

How do I estimate sensitivity of two outcomes variables from a difference-in-differences setup?

Say I estimate the following multi-period DID equations separately: $\frac{Y^1_{it}}{A_{it}} = \alpha^1_i + \alpha^1_t + \tau^1 D_i\times Post + \beta^1C_{it} + \epsilon^1_{it}$ ...
0
votes
0answers
5 views

What value should I assign for cases in which the attribute is not calculable?

I have a dataset of positive and negative examples for a certain class and I would like to know whether or not the positive examples of this class are significantly better (or worse) in one of the ...
0
votes
0answers
34 views

mixed model vs repeated measures oneway anova : different FDR

I need to understand why, in this simple simulation, does repeated measures anova's false discovery rate is kept at 5% when that of mixed model is about 10 % ? I simulated 1000 sampling and ...
0
votes
0answers
22 views

Model selection for differences in outcome (binary) across groups?

The problem: A group of agencies (n ~ 20) performance varies significantly on a binary outcome from 0% to 100% (both with small n, more commonly from 20% to 60% for larger n agencies). Is this an ...
0
votes
0answers
62 views

Friedman test for a repeated measures experiment with replicates

(Please see example with reproducible data at the end) I have a data file with the results of an exercise performed 16 times with each of 2 control devices by 3 subjects. I measured the task ...
2
votes
0answers
71 views

Group wise imputations allowed?

What is the correct way of imputing missing values? We are trying to predict the label of persons belonging to group A or B. The alternative hypothesis is that there are differences in parameters for ...
8
votes
0answers
97 views

10 % false positives from nonlinear mixed effect models : Why?

I've run a simulation study in order to estimate type I error rate of the test of group effect in a nonlinear mixed effects model, using nlmer from lme4 package. The results show there is 8-10 % ...
1
vote
0answers
30 views

Measure how different are two groups in their answering on 25 ordinal variables

The research context: I'm interested in usage frequency of special interest websites and its predictors. I asked individuals (n=1000) for the usage of 25 different websites in 25 items in a survey ...
1
vote
0answers
74 views

How to detect different social groups in a small questionnaire dataset?

I work with a very small questionnaire dataset, in which perception of 10 respondents to the size of, say, an unseen population is quantified: The population is divided into eight sub-populations, and ...
0
votes
0answers
6 views

Separate-Sample versus Pooled-Sample Estimation of Interactive Effects

I have a question regards pros and cons for Separate-Sample versus Pooled-Sample Estimation of Interactive Effects, when alayzing group differences. For instance, I am interested in the effect of a ...
1
vote
0answers
220 views

What statistical analysis should I use for this (attached) dataset?

I have a dataset of 815 positive examples and 9492 negative examples for a certain class. Each example is represented by 12 features and a target label (i.e. TRUE/FALSE). The dataset is in a CSV file ...
0
votes
0answers
29 views

Test for group differences in a piecewise OLS

I have a piecewise regression and need to test for group differences. I want to test whether the two groups (a categorical predictor) differ with respect to a continuous, independent variable's (IV) ...
0
votes
0answers
31 views

compare groups taking into account confounding factors

I have data from human participants in a study and I am using MATLAB to analyse it. The participants are divided in 4 groups according to their disease severity. The demographic characteristics of the ...
0
votes
1answer
55 views

Difference between regression between groups vs across all subjects (continuum)?

I'd like to understand this better in terms of drawbacks and suitability. For example, if my data includes investigating differences between 2 patient groups and a control group (3 groups in total), ...
0
votes
0answers
10 views

Testing groups with categorical observable for significant difference

I am looking for a suitable statistical procedure to find groups of variables that are not statistically significantly between them when I have several dependent variables. I have a table containing N ...
0
votes
0answers
10 views

Which variables characterizes the separation of speakers into two known groups

I have 40 patients for which 12 summary measures have been computed. Some of the measures are somewhat correlated in the data, but measure quantitatively different things, so I would like to keep ...
1
vote
1answer
67 views

Linear trend for correlations

I am evaluating three independent samples (1-3). For each sample I have calculated a correlation of variables A and B. I am now interested if there is a linear trend in the development of the ...
0
votes
0answers
32 views

Two groups, 29 Likert scale questions - differences between the groups?

I've two groups of individuals, Group A (13) and Group B (30). Both groups got the same series of 29 questions that can be asked as "unimportant - slightly important - moderately important - very ...
2
votes
1answer
52 views

test for difference between two differences (proportions)

I have 4 independent samples. Two groups A and B measured on time1 and two groups A and B measured on time2. For every group I calculate a proportion. I would like to compare the difference between ...