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

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Differences between Distributions [closed]

I have three samples with different values about same random variables. I want to test the difference between the three distributions (position, shape, etc...) You can suggest a list of tests to do ...
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59 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 ...
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24 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 ...
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24 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 ...
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21 views

Comparison between groups with one group normally distributed, and the other skewed

I want to compare continuous numerical variables between two groups. Sample size is small (27 for one group and 43 for the other). I use Shapiro-Wilk test to check for normality of distribution of ...
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1answer
27 views

Comparison of ratios between multiple groups

I need to perform statistical analysis whether there is any difference in the usage of each gene version between disease groups. I have 3 groups, in each group there is a different no. of patients. ...
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1answer
15 views

Overview of concepts of the methods that this Single-Cell Differential Expression (SCDE) tool uses?

I'm unsure about how this tool works, but as I understand it, it tries to use Bayesian probability in order to differentiate the two different groups from each other as well as some other methods. ...
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27 views

Independence between sibling groups?

I am a novice at statistics and I would sincerely appreciate your help with my question: I am working with a control group and 2 sibling groups and have a mixed design (i.e., one withing group ...
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24 views

Okay to use oneway ANOVA to compare these 3 group proportions from aggregated dataset?

My situation: I am assessing outcomes of a university course redesign. One of the goals of the redesign project was to increase successful course completion, as measured by a decrease in the course ...
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30 views

What is the relationship between differential analysis and hierarchial clustering?

I'm currently in an internship for R bioinformatics, where I'm writing software for single-cell RNA sequencing analysis. We're looking for differentially expressed genes between groups, but I don't ...
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26 views

Figuring out which test to use

It's been a while since I've taken a stat's class and I came across a problem I need to solve. I was hoping someone could point me in the right direction. I know a question similar to this has ...
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1answer
22 views

How to quantify whether the difference between two groups is relevant?

I'm sorry that I am not at all an expert in statistics, so my question may sound vague, or very easy. I have a group of people that I divide into two categories, $A$ and $B$, depending on some ...
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1answer
29 views

Why does randomising the order of measurements remove time as a confounding variable?

Say we're interested in the difference in x between Group1 and Group2. We might measure 50 samples from Group1 then 50 samples from Group2. If the accuracy or precision of our measurements change over ...
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13 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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1answer
36 views

How to quantify the similarity/difference between groups of selected features?

Since I have a imbalanced data to deal with, I randomly down-sample the negative data to reach balanced data for following feature selection and classification. To test feature's robustness to ...
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20 views

Measure for comparing serial measurements of multiple variables in treatment vs control group?

Can anyone suggest whether I am going about the statistics in an appropriate way? I have two groups of populations which have similar characteristics. In each member of both groups, serial ...
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29 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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1answer
94 views

Comparing failure rates between 2 products with different number of deployed equipment

I have the following scenario, which I am trying to better understand. There are 2 different brands or groups of devices performing the same functionality as such: - Product/Brand 1 has 4,323 devices ...
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27 views

Pretest-posttest comparing two treatment modalities

I am not a mathematician, and have not studied statistics in 8 years. Medically trained conducting experiment for University, sorry for my ignorance. I am using an identical pretest / posttest, ...
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39 views

Difference between treatments with binary outcome & sample size estimation - Stata

I have 20 binary outcome variables that I want to test for association with a nominal 'treatment' variable with 6 categories (a,b,c,d,e,f). For the outcome that is significantly associated with ...
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50 views

ANOVA not significant but t-test significant

I have survey responses from people from 10 countries (sample range from 10 to 71 response per country) and I am trying to see if there are significant differences between the people of each country ...
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6 views

Using interaction terms to exclude sample members who do not meet certain conditions?

I believe this might be a specific application of the non-compliance problem in experimental design and estimating treatment effects, but I could be wrong. I want to model the impact of certain ...
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1answer
34 views

Is difference in proportions due to sample size?

I am currently working for a project team that is trying to reduce the number of defective parts produced in a factory. Without going into too much detail, the plant has a safety procedure where they ...
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39 views

Normalize data with kurtosis > 1 for one group

I want to model my variable using mixed linear modeling, but the problem is that target variable has a very high kurtosis for one group. The distribution is totally normal for other group. ...
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18 views

Comparing differences in pairs of ratings using a bootstrapping like approach

I'm pretty new to bootstrapping like approaches. So I do apologize for any inconvenience. I have two independent samples, snow (n=120) and nonsnow (n=608), consisting of pairs of ratings on a ...
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33 views

Power calculation for non-significant pilot study?

I have performed a pilot study comparing the means of two groups and I've yielded non-significant results. I wish to determine whether increasing the sample size would have produced a significant ...
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51 views

Strategy for geometric die guessing game

The first day of statistics class, we played a betting game to visualize the basics of probability distributions. It worked like this: The teacher begins by rolling a die repeatedly until the number ...
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61 views

At what point do significantly different groups start to differ?

I have two groups: a control group (N = 91), and a treatment group (N = 54). I did a t-test in SPSS that suggests that there are significant differences between the two groups in terms of the variable ...
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14 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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1answer
83 views

What test(s) should I use to compare 2, non-normally distributed populations with unequal variances? (IV is 2 categories; DV is ordinal)

I'm a bit stumped as to what test(s) is/are most appropriate for the following scenario. I found a couple of similar questions but wasn't sure if the answers applied. For a report I am working on for ...
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14 views

What's the best stats to use for pre/post data?

I have 107 participants and had them do 2 lessons. Before lesson one, I asked 5 knowledge questions with true/false response for each. After the second lesson, I administered the same survey ...
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1answer
41 views

Testing if subpopulation group is different from population group

Say I have data about the distribution of age groups in a country: 0-10 y : 20% of pop (or 3,000,000 people out of 15,000,000 total) 10-20 y : 30% of pop etc. ...
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78 views

conditional difference between 2 uniform random variables. Surely Breiman can't be wrong?

I've already searched and don't find this particular case in XValidated. Statement: "Electricity is turned on uniform-randomly at a given time of day (in 24 hour window). Once it has been turned on, ...
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6 views

Moderation with the outcome variable

I'd like to know how one can do moderation in the following scenario: Randomized experiment for a group-level intervention. HLM has already shown impacts of the intervention on individuals. The ...
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39 views

Searching for signal in a somewhat noisy landscape

I'm trying to implement a system to identify regions of high signal content in the presence of a noisy landscape. By high signal content, I simply mean intensity values significantly above background ...
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393 views
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16 views

Iterative Differential Expression Analysis for Multiple Categories

I have a dataset which consists of one categorical variable and many numerical variables. This is how my data is formatted: ...
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1answer
63 views

How to calculate the average age of a subgroup

Just to confirm my findings to a group of data scientists... I have a data set with patients visits and among others the death age of deceased patients. If I then look up all diagnoses the patients ...
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1answer
30 views

Sample size for group comparison

I am collecting data from 3 different population groups (islands) and within each, comparing children from class 1 from 10-14 schools between two groups - those who completed kindergarten, those who ...
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118 views

Can the difference between the means of two groups lie outside the confidence interval for the difference?

I received this question from a colleague which left me with a desire to find out a bit more about it. If you have two groups A and B with means--for example, 7.9 and 5.8--is it possible that the ...
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48 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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22 views

Testing if two population means are equal

In the situation where I have two estimated population means, and I want to see if they are equal, I compute $\frac{ \bar{y_1} - \bar{y_2} }{ se(\bar{y_1} - \bar{y_2}) }$ and compare to the ...
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2answers
136 views

Creating groups using two continuous variables without using median-splitting?

I have two continuous variables, one of individuals' retrospective childhood anxiety and another regarding their current level of anxiety. Research has demonstrated that during a snapshot of ...
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20 views

What are the conditions for Pooling Samples

I am trying to understand when it is ok to pool samples. The problem i have is that with more then two samples, it is possible that pairwise comparison of the samples could lead to the following ...
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1answer
34 views

Significance of differences between two scenarios

CAPTCHAs are used to distinguish legitimate human users from computerized programs that are trying to abuse online services. There is a way to bypass the security by relaying CAPTCHA challenges to ...
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16 views

Significance of effect on several variables

There is data about a supply chain model available. Below, you can see means of the calculated performance measures cycle time, return of investment, and service level for different forecast errors. ...
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1answer
49 views

Find whether one mean is very different from all others in multiple measurements

I have many data frames like the one reproduced below in R. I am trying to find cases where one group only is very different from the other groups (I have a variable number of groups for the different ...
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46 views

Comparing Frequency Distributions with non-categorical data

Rather than try and contrive things, I'll just give you the data as is. This similar to the ideas found here. I have two population from a control group and a disease infected group. I want to ...
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55 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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85 views

Difference in proportion: Pre-post intervention-control study design

I am conducting a meta-analysis where I want to compare the proportion of samples pre- vs post- intervention. To do this, I have been calculating the difference in proportion (Post - Pre) as the ...