Questions tagged [group-differences]

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

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Compare slopes between two groups of equal size

I want to compare how does a dependent variable (total flow) changes with a covariate (total rain) between two groups (stream A & B). Usually, i would go with ANCOVA. But these groups have the ...
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53 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 ...
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110 views

Time series group comparison

I am currently analyzing a time-series experiment and I have some difficulties to come with a nice comparison of my groups. I was hoping someone could help me. The design is the following: Three ...
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101 views

Determine Chi Square Group Differences in multiple choice questionnaire

I'm trying to determine if there is a group difference in answering a multiple choice question. For example, I want to answer the question of, do "Change Instigators" (group A) answer "communication"...
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255 views

Intuition behind fixed effects

Im trying to explain the intuition behind fixed effects to a group of people with no background in (formal) regression analysis. Explaining the intuition behind Diff-in-Diff estimation of the impact ...
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32 views

Test for participant subgroups in gradual means shift

In an experiment with 44 participants I have measured the response time for a set of stimuli, where the response could be a or b. The means of the two responses do not differ significantly (783.3 vs ...
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4k views

Averaging z scores when doing a “group by”

I have a dataset where each row is an hourly measurement of certain fields (columns). For each column I then add another column that is its respective z score relative to the entire population. If I ...
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408 views

Using similarity matrix to measure diversity of a group

I wish to measure the "diversity" of a group of objects. Right now I'm using Euclidean distance to compute the similarity matrix between all the objects in the group. I'm searching for a measure of ...
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520 views

Two-sample bootstrap?

I have two independent samples of observations. From each sample I produce a statistic. Let's denote these as $\theta_1$ and $\theta_2$. I'd like to test the hypothesis that $H_0: \Theta_1=\Theta_2$, ...
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353 views

Heterogeneous Treatment Effects - How to test differences in the ATE?

I want to conduct a simple propensity score estimation where the treatment $D_i$ is a binary variable ($D_i=1$ individual $i$ participates in the labor market program, zero otherwise). I estimate the ...
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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 ...
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69 views

How do I test for a difference in the standard deviations of two groups?

I have two groups and I want to know if there is a difference in standard deviation (or variance if it's easier) for each parameter. Here is a table of descriptive statistics for my data: After ...
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1k 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 ...
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83 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 ...
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138 views

Generating predicted mean values and CIs across different groups in lme4

I’ve run a mixed-effects model with crossed random effects in glmer and ultimately want to show a bar graph depicting mean predicted values (and associated confidence intervals) across years within ...
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309 views

When/how should I bucket/recode/group certain categorical levels in an “others” level?

Imagine I have a dataset with a categorical variable with many levels, and I want to use this dataset for binary (positive/negative) supervised learning. In this categorical variable certain levels ...
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23 views

Find significantly different element

I have following data and want to know is there really significant difference between those five objects: I have 5 objects and 3 different tests and their results like this. So this is very few rows ...
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433 views

Comparing differences between overlapping groups

I am trying to analyse the differences between people who vote in the European Parliament (EP) elections and people who vote in national elections, based on the EES dataset (http://eeshomepage.net/). ...
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72 views

Determine how much and why a sample differs from its population

I'd like to be able to determine a) how much and b) why a non-random sample “differs” from the population (there's probably a better word than “differs”; I was tempted to use “does not represent” but ...
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2k views

First-differences vs. pooled OLS

Two-period panel regression model: $Y_{it}=\beta_0\delta_{t2} + \beta_1X_{it} +\alpha_i + \epsilon_{it}$ where $t=1, 2$ $i=1,...,n$ indexes the cross sectional units drawn via random sampling. $\...
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482 views

How does my questionnaire analysis plan sound?

I will soon have the results of a questionnaire that I have carried out, and I have made a plan on how I will analyse the data. I was hoping that someone could comment on my plan to advise me. About ...
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57 views

How to test difference between two groups of data in one line

Usually, we can test difference of two groups of data by adding the dummy variable. But my question is, if these two groups of data in the same line, but they concentrate at the different part of this ...
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74 views

Simulating groups different with respect to the orthogonal complement in R

In a paper of Journal of Chemometrics (Naes & Mevik 2001 : Understanding the collinearity problem in regression and discriminant analysis), the authors propose to make simulations by creating two ...
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335 views

If I compare conditions within two preexisting groups is that a quasi-experimental design?

I have two groups of participants, one group of psychosis patients and one group of controls. All of the participants complete a computer task that has three different conditions. So, I want to make ...
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82 views

Hypothesis test for population rather than for sample

I have a set of data for companies in a certain industry. The data set spans two consecutive years, 2000 and 2001. Let's say I have 100 unique companies in the dataset and I calculate average ...
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384 views

Performing comparisons after a cluster analysis

I have a data set of about 40 subjects, and 10 variables, some measuring performance on a task, and some measuring some characteristic. Each of the performance variables consists of the proportion of ...
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2k views

How to test group difference between nominal and ratio data with nonparametric tests?

In my data the dependent variable ‘vocabulary uptake’ is measured as scores ranging from 0-10 and the independent variable is yielded from a ‘reading intervention’ with 4 different reading conditions (...
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39 views

What test(s) for my data?

I'm trying to analyse data for my psych undergrad dissertation but struggling with which tests to use because my project is unlike anything I've had experience with previously (and also I don't have a ...
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163 views

How to test whether two means of categorisation generate significantly different results

If I have the following contingency table in which Novel.Cat is a new means of classifying some thing. Ref.Cat is the gold ...
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38 views

How to symmetrically adjust data by removing certain value

Say I have a data set in the following format: {a:200, b: 100; c:400} The sum of a, b and c equals 700. Now, I have another value which is supposed to be the actual total say 500. How do I adjust ...
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27 views

Group comparison for extreme value data: which method is suitable?

I have measured Gaussian curvature data of 3D objects from two different groups, A and B. I would like to find out whether the objects differ in curvature. The distribution of data values for each ...
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11 views

What can I use to compute a similarity (or diversity) index for a sample with “multidimensional” attributes?

Current problem: We have a batch of $n$ items for which we capture their details with $m$ attributes. It could look something like this: The goal is to compute an "index" that says how "similar" this ...
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13 views

Appropriate method to assess scatter or variation in groups with dramatically different means

I am working on a product fabrication process, and I want to demonstrate the consistency of my product. To do this, I am trying to measure the variation in the extent to which a biological material is ...
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17 views

How to define the cut off point?

I have population of 218 people operated on after a certain event. They are operated on from day 30 to day 911 after the event . Some of them were OK (0) and some got a complication (1). I would like ...
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98 views

Find significantly differences between multi-variant groups

I have 11 groups, each consist of about 200 observations, and each observation has 2 variables (which are actually the first two PLS components if it makes any difference). Each group is a substance ...
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52 views

Comparing the means of two groups when a large number of data points have the same value

I have data on the profitability of wagers made according to two different strategies. One strategy was to bet $1 on the underdogs in each of a sequence of sporting matches. They have data like this: ...
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62 views

Time Series sampled at varying frequency - Employ Linear Mixed Model to compare trends?

I hope that this question has not be asked like this elsewhere, if so I could not find it during my google research.. I have the following problem: I have data sampled from different sensors("ID") ...
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20 views

Randomized Treatment within treated group

I don't know if this situation has a particular name. I'll just give the example and my question. Suppose we have two naturally concurring groups, $A$ and $B$. By that, I mean there is a naturalistic ...
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146 views

T-test with nested data

I want to test gender differences in an outcome variable called the willingness to pay. My data consists of records with following three fields: ...
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32 views

Comparing observed and expected diets of two different species

My data consists of dietary data from two species (C1 and C2) and expected diets for each species (E1, E2) generated from a combination of variables, but is based on their foraging behavior. What I ...
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47 views

Is log based transform comparable across groups with different minimum values?

I have data for different groups that includes positive, negative, and zero values. Here is an example: group1: c(-503583,-395833,0.1,3835,19,-0.001,0,48400883) group2: c(-39,-8340,-10,0,0.1,2889,93,...
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53 views

Difference in distribution of multinomial distributions

I have some questions regarding how to analyse catagorical data, summarised as percentages on an individual level. In the data in question, for each individual we know the fraction of biological ...
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37 views

Combining intra and inter cohort comparison using panel-data

After reading numerous posts, I still haven't found a conclusive answer to my question. I have panel data for the whole population(multiple years, interlinked by personal identification numbers), ...
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74 views

How and when to use multiple comparison tests

There seems to be some variability in WHEN multiple comparison tests such as Bonferroni or FDR might be implemented. Type 1: One might carry out multiple one-way ANOVA's to see whether or not there ...
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188 views

Testing difference in proportions with bootstrap

Summary: I want to perform a bootstrap test on the difference of proportions. I think this is equivalent to testing the difference between means using bootstrap, but I wanted to clarify some details. ...
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19 views

Correlational Meta-analysis

I conducted a correlational meta-analysis. There were three groups of behaviours and one aggregate effect size for the correlation between each behaviour group and a continuous measure. We used ...
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27 views

Binomial task data: proper statistical test to use for comparing treatment to control groups?

I have fairly simple task data that involves either correct/incorrect responses (binomial?). In the control data, there are 50 trials per subject, in condition 1 there are 50 trials per subject, and ...
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20 views

Determining two groups when only associations are known

DNA tests for genealogy provide the user with lists of people who match them on specific segments of their DNA. When 3 or more people all match each other on a segment, they form a Triangulation Group ...
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17 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 ...
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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: $...