Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [group-differences]

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

1
vote
0answers
16 views

How to compare 4 short time series in order to say if they are different?

I made a degradation test using 4 different chemical treatments as time function. How can I know if there are significative differences between the treatments considering that they are as a time ...
1
vote
1answer
35 views

t test alternative when participants can belong to multiple groups?

Newbie here, so please excuse any faux pas. I have participants who belong to different groups: A & B. However, a participant can also belong to both groups or to neither. Possibilities are A, B, ...
0
votes
0answers
13 views

Detect changes in dataset

I need at least a couple of keywords to get me started and read for my self. Suppose I have a number $M$ of populations. From each population, I draw $R$ replicas of a parameter vector $\vec x$ of $N$...
1
vote
1answer
31 views

What test to use to see if there is a difference before and after an intervention?

I have a data set constisting of gender and years (2010 representing before the improvement and 2012 representing after the improvement) and another table comparing age against the years: ...
2
votes
1answer
76 views

How many times should I difference a dataset?

Im currently reading The Foundation of Modern Time Series Analysis by Terrence C. Mills. In the fourth chapter he discusses the concept of difference data to remove secular trend and the history ...
1
vote
1answer
386 views

Power analysis of a permutation test

How could I perform a power analysis of a permutation (randomized) test? Also if you know some R package I would be greateful for any recommendation.
1
vote
0answers
42 views

Alternate form of null hypothesis for equality of group means (Helmert matrix?)

I have two sets of hypotheses in a multivariate setting that are said to be equivalent. I am wondering if someone can explain why they are as opposed to me just taking it to be true. Version 1: $...
0
votes
1answer
32 views

Can I use logistic analysis for two surveys that were conducted at two different time points

I have a two data sets - through two surveys that were conducted in the same organization at two different time points (couple of years apart). Both the surveys were to test if people experienced the ...
1
vote
0answers
33 views

Power calculations for difference in means of proportions

How would you conduct power analysis for comparing means of a response that goes from 0 to 1? -- e.g. comparing the mean test scores of two groups of students, where the score can range 0-100%? This ...
-1
votes
1answer
39 views

Evaluating Groups Based on Multiple Variables

I have what seems like a simple question, but I've been trying to find a solution all afternoon with no luck. My dataset that includes a number of continuous variables, and two different grouping ...
0
votes
1answer
42 views

What kind of statistical test should i use? Two before and after variables to eachother

I am performing an experiment using caffeine and testing the resting blood pressure before and after caffeine consumption as well as cognitive performance using the Stroop test. I've performed ...
0
votes
0answers
19 views

data analysis 4 participant groups from questionnaire data

all of my data is being collected from an online questionnaire. two of the questions will act as independent variables and will allow me to sort the respondents into groups for analysis. I will have 4 ...
1
vote
2answers
39 views

Calculating if there's a significant difference between the difference of two sets of groups

I measured the speeds snails fell off in a high-speed aquarium, where current was created by me opening a valve to different degrees, leading to the speeds that snails could fall-off at being set and ...
0
votes
0answers
101 views

How to test whether subgroup is influential in overall group mean? (whether removing a subgroup affects results/all-but-subgroup mean != overall mean)

This question is similar to this one but I want to test whether the all-but-subgroup mean differs from overall group including the subgroup. This is DIFFERENT FROM THAT QUESTION in that the question ...
0
votes
1answer
38 views

How can I determine if there's a statistically significant difference between distributions in 3 groups?

I have 10 sample zones. For each zone, I have data for about 1000 parcels reporting the %of grass, shrubs and trees within the parcel. My 10 zones belong to 3 broader categories. How can I test ...
1
vote
0answers
22 views

Test for Statistical Differences Among GLM Modeled Data

I have three independent data groups - the groups are comprised of census tracts. Each data point (tract) within each group has a modeled estimate of disease prevalence (% pop that is obese as an ...
2
votes
1answer
141 views

If one group's mean differs from zero but the other does not, can we conclude that the groups are different?

I have many pairs of measurements. A paired-samples t-test on these produces a 2-tailed p > .1 (so non-significant by typical alpha values). When I run two separate one-sample t-tests comparing ...
3
votes
0answers
52 views

Doing the equivalent of a dependent t-test on a sample of correlation coefficients

I’m doing an analogy of the following study. I take participants etc. and show them a picture of man 1 and have them rate his attractiveness and rate his intelligence just from his picture. I then ...
1
vote
1answer
66 views

Trying to get the relative difference between two groups with negative values

I have two groups A and B which have few duplicating values. So the overall data point is less than the summation data points from group A and B It's because group A and B data are simply taken out ...
0
votes
1answer
25 views

How to research very unbalanced groups

I have a data set for a PhD paper in which I need to look for differences between 3 groups of observations. The issue is that ~95% are in one group and the rest are in the other two. The data table is ...
0
votes
0answers
278 views

Finding statistical significant difference between multiple linear regressions (in R)? [duplicate]

I have a faceted graph, and I want to be able to test whether or not the slope of one regression line in one of the division is significantly different from both a) the other lines within its facet, ...
1
vote
2answers
89 views

Is a mixed model appropriate to compare (continous) outcomes between (categorical) groups, with no other parameters?

Design I have hierarchical data with three categorical levels: group, person, and cell. In group A, B and C I have some unequal number of people. For each person a to zzz I have some unequal number ...
0
votes
1answer
28 views

qualifying sample similarity / difference using population standard deviation

I have a set of students with mean height of 100cm with standard deviation of 10cm. I want to be able to qualify a student based on his/her height relative to the mean height for the group. Would it ...
9
votes
2answers
181 views

Investigating differences between populations

Say we have a sample from two populations: A and B. Let's assume these populations are made of individuals and we choose to ...
0
votes
0answers
58 views

Calculating average gender diversity at companies of various sizes

We have a dataset that lists employers in a fairly unique industry, the number of employees they have and the breakdown of employees as male or female. The size range of the companies in this ...
1
vote
0answers
45 views

Determining standardised difference between two data vectors with negative values

I am using Matlab to determine the standardised difference between a treated group, A, and a control (untreated) group, B, to eliminate the effect of size of baseline (B) value and to therefore ...
2
votes
0answers
87 views

Can I fit a linear mixed effects model to these grouped data?

Data and Objective The data are about lane change maneuvers. I want to predict the lane change duration of a driver of certain age and gender. Following is a very small subset of observations and ...
1
vote
0answers
30 views

may i use multiple t-tests to examine group differences?

I've got a critical comment on my recent manuscript on cultural comparisons. There were two different samples depending on collection method (classroom vs. online) in both culture A and culture B. So ...
1
vote
1answer
674 views

Mixed effects model for group differences in R

I'm trying to run a mixed-effects analysis on some data that I have, but cannot determine if I am using the correct model. First, I am trying to determine if there are between-group difference in 5 ...
1
vote
1answer
821 views

Exact Negative Binomial Test with edgeR

I have to select genes differentialy expressed by using the library edgeR of R. My problem is that the function ExactTest tests for differential expression between two groups of count libraries. It ...
1
vote
0answers
40 views

How to compare two cumulative distributions if the number of observations per individual are different?

Problem Description I have simulated the movement of cars in a lane. The simulation model was first calibrated based on an observed car traffic. Now, I have vectors of speeds (collected every 0.1 ...
0
votes
1answer
28 views

Statistic for a set intersect

I have two set $A$ and $B$ with $C = A \cap B$. Given are the sizes (finite) $|A|,|B|$ but not $|C|$. I have random sample from $A \cup B$ where for every $x \in A \cup B$ I know whether is in $A, B$ ...
3
votes
1answer
749 views

testing the difference between two meta-analytic effect-sizes

I would like to know if it is possible to statistically test for difference between effect sizes (Hedges g in this case) For example, let's say I have run a random effects meta-analysis on $20$ ...
1
vote
0answers
20 views

Compare grades of cohorts

I want to compare the grades of two cohorts A and B (of unequal size). I have the grades for a certain course 1. The grades are not normally distributed. I used the following code (in R) to compare: <...
0
votes
1answer
255 views

How is independent T-Test valid for unequal samples?

I have two groups that I wish to assess for statistically significant differences (n1=1520 / n2=115). I'm actually using T-Test for independent samples. As far as I know, there isn't a problem here ...
3
votes
1answer
114 views

Test for difference between time-series measurements

I have an experiment where the response to a treatment is measured over time. I now want to test for if the response profile differ between the treated group and the control group. There are ...
-1
votes
1answer
53 views

grouping of groups (ANOVA)

Background: One of my hypothesis' is that several (more than 2) groups (hereafter sub-groups) can be grouped, based on an interval-scaled variable, into two groups that, based on the same interval-...
0
votes
0answers
16 views

Which method can we use to test the quality of the final ranking of a group?

Suppose we have 10 people give their ranking on 4 items. Then we use a method to get the final ranking. Which statistical methods should we apply to test the correctness of the result? Can we use ...
1
vote
0answers
45 views

Comparing variances of variables derived from samples of different sizes

I have a data frame, which I group by some variable v. Then I: subgroup the variable further by month for each month, I compute log loss and ROC AUC for points in a given group (level 1 grouping) and ...
2
votes
1answer
52 views

Comparing means between several groups

I am asking for your help. I have 3 variables that are divided into 4 groups (Quantitative variables). I intend to check if there is any difference between the groups for each variable. My ...
1
vote
1answer
65 views

What method / technique I should use to compare two groups of people when the data is non-normally distributed data?

I am going to compare means of two groups (Male, Female) from my complex stratified sample. I have scores of 3 subjects of more then 3000 respondent for each subject. I checked for normality and get ...
1
vote
1answer
20 views

How can correlational analysis be used to create groups

The goal is to have groups emerge bottom-up from the data. I have a number of measures (variables A, B, C, D), each with a value 1-10, for a large number of subjects. Now, knowing that there will be ...
1
vote
0answers
13 views

Is it logical to find difference between same question, same people yes/no answers but different time?

I have 22 patients with certain symptom (have(yes)/don't have(no)) before and after treatment. Is it logical to find difference between having or not having the same symptom after treatment? For ...
0
votes
1answer
381 views

Comparing multiple likert items across two groups - is the MANOVA appropriate?

I would love to compare 9 multinomial (4 point likert) and 2 binomial (yes/no) measures across two independent groups but I am not sure what test is most appropriate. Treating the group as the ...
0
votes
0answers
580 views

Non-parametric mean comparison with 2 unequal samples?

As an spanish speaker, I apologize if my technical english isn't 100% accurate. This may be a simple question, but I haven't found a clear answer. I have two independent groups: Group A: n=1520 / ...
1
vote
0answers
59 views

Which is best method and interpretation for a single-group pre-post model with interactions?

I have some one-group pre-post data where the outcome is a score and an IV of interest is the whether or not the subject has performed the task in the past. I am looking at this in a few ways and am ...
1
vote
1answer
196 views

How to find groups in data divided by difference in one variable?

I`ve got a question concerning Student Alcohol Consumption dataset. http://archive.ics.uci.edu/ml/datasets/STUDENT%20ALCOHOL%20CONSUMPTION Please, help me to realize which methods\models (python and ...
2
votes
2answers
60 views

Combination/Permutation Dilemma

This is probably quite a straight forward one - but still struggling to get my head around it. To explain my problem: In my work, I'm trying to put subjects into groups of 4 for a second round of an ...
1
vote
1answer
118 views

How do I test which of two algorithm is perceived better?

I am trying to evaluate which of two algorithms is preferred by people. The algorithms generate images and I've shown the generated images to different people and asked them to vote on whether they ...
2
votes
1answer
6k views

How do I report and interpret the output from linear mixed models with interaction terms?

So, we are doing a linear mixed effects model for analyzing some results of our study. In short, we have performed two different meal tests (i.e., two groups), and measured the response in various ...