Questions tagged [group-differences]

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

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568 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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1answer
3k views

Comparing the result of a study which has unequal group sizes

I have conducted two user studies and in my studies I didn't have control over the group sizes. In each study users were put in groups and they were asked to perform some group activities. Here is the ...
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23 views

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 ...
3
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120 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 ...
3
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107 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"...
3
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1answer
389 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 (METs)...
3
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0answers
267 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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33 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 ...
3
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0answers
422 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 ...
3
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0answers
369 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 ...
3
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1answer
154 views

How to measure the effect of users' participation in forums?

My problem is how to measure the effect of a user's participation in forums. I calculate the user's participation as the number of discussions that user posted. My hypothesis that a users' ...
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250 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. ...
2
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1answer
79 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 ...
2
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0answers
92 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 ...
2
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1answer
55 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 ...
2
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1answer
577 views

Principal component analysis with non-independent observation

I have observations with 6 individual-level characteristics from 2000 units in 56 groups (villages). I know that within groups, characteristics are strongly related as individuals influence each other....
2
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0answers
80 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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0answers
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 ...
2
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0answers
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 ...
2
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0answers
146 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 ...
2
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373 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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471 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/). ...
2
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74 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 ...
2
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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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1answer
49 views

Are slopes of calibration experiment different?

I'm running a calibration experiment for an instrument that measures soil moisture content. I have 6 buckets filled with different soils that I weigh daily and at the same time take a measurement with ...
2
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0answers
483 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 ...
2
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0answers
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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0answers
75 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 ...
2
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338 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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0answers
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 ...
2
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0answers
404 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 ...
2
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0answers
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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0answers
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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0answers
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 ...
2
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0answers
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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2answers
21 views

Proportion test: one sample or two sample?

We introduced a new way of teaching children this summer. We then split the children (As randomly as possible) into 2 groups. Group 1 children were taught in the new style, Group 2 children were ...
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0answers
18 views

How to detect calendar effects for stock prices (day-of-week, month, etc.)

This is a python/pandas question just as much as it is a statistical one. How would I go about determining the typical delta for day-of-week and month effects of a given time series? Taking the day-...
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1answer
30 views

Comparing the difference between two mean differences (x1 - y1) vs. (x1 - y2)?

Could I get advice on what statistical test is most appropriate assuming the data conform to assumptions made when running parametric tests. I have conducted a study with 4 conditions (one control, ...
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0answers
28 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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0answers
12 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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0answers
14 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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0answers
18 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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0answers
145 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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0answers
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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0answers
81 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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0answers
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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1answer
232 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: ...