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Paired data arise when an experimental or observational study design deliberately samples two units as a dyad to form a basis of comparison. Use this tag for any question about paired data or their analysis.

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Paired t-test of a non-normal data with sample size 66

I have a paired data with n=66. I understand that normality condition of differences data should be met to conduct a paired t-test. However, from the histogram, it doesn't appear so normal. The p-...
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Help with a study-design for comparing subjective assessments using different methods

First post, so please be kind... Not sure if the forum is correct, but it was the best fitting on Stack Exchange, so here goes! The following situation is to be examined/evaluated, and I am at a ...
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Proper statistical method for comparing two annual time series of different measurements on same area

Lets say I have two annual time series - one is in-situ measured Sulphur input to given watershed and the second one is some index (number) acquired via remote sensing (satellite images) over the same ...
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One-tailed test for comparing paired dichotomous responses

Given reference samples $R_i$, I have two dichotomous responses $X_i$ and $Y_i$ I wish to compare. Each dichotomous response (relevant vs. irrelevant to the reference $R_i$) is generated by an ...
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Follow up medical study with missing data

I am analyzing some patient data for a medical study that has a duration of several years. Once a year, the patients are expected to visit the doctor, where they get four treatments, say A, B, C, D. ...
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25 views

emmeans pairwise contrasts result in same output values for all?

First of all, I am a beginner at mixed models, so I beg your patience and advice if this post could be improved. The structure of the data: ...
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1answer
48 views

t-test or paired t-test to detect drift for suicide prediction

Context and data I am studying suicides among the military. I created a table that aggregates certain metrics (number of holidays, number of hours worked, etc...) for each officer, for each month ...
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31 views

Paired samples t test in Python

I'm trying to conduct a paired samples t-test in Python (statsmodels package), but I don't see a function for it in their documentation. The closest I can find is ttost_paired, but I don't think its ...
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37 views

Paired tests for one-to-many matched observations

I have a propensity score matched data after 1-to-2 matching. Each treatment case is matched to one or two control cases. May I use paired tests to compare the outcomes? The discussion https://www....
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40 views

Paired t-test or repeated measurement

I am designing RCT in the same patient (treatment on one side of the face and control on the contralateral side of the face) The RCT will be 1 month long with measurements happening at 2 and 4 week ...
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22 views

review language please?

Our biostastistician is on vacation and im pulling my hair out. Can someone help me with a few things? I am comparing means on paired samples , i have six variables to compare means on. - is the ...
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19 views

Which test to compare Vitamin D serum level between malignant and benign tissues

I have Vitamin D levels for both malignant and benign tumor types and I need to compare them. Which test should I use, unpaired t test ? Another question; I have also PSA level ( also continuous data ...
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Which statistical test to determine interaction effect?

I conducted an experiment to determine the effect of blood type on blood cell interactions with proteins of differing blood groups and want to determine if there is an interaction effect for the ...
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paired T test: how to plot it?

What is the best way to represent a paired T test comparison for a sample with N=200 and 5 variables (only one of which is important)? nonpaired T test is not significant. A before-after graph is too ...
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General Procrustes Analysis - Appropriate Statistical Test for Repeated Measures

I have a question regarding General Procrustes Analysis (GPA) and was wondering if anyone has any advice. I am trying to test whether my data collection method is replicable between researchers. I am ...
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testing for difference in means across N pairs of samples

I have N different populations. Within each population, I have an equally-sized pair of sub-populations: $(t_j, c_j)$ for $j=1,N$ For each pair in each population, I have the measurement of a mean. ...
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Non-parametric ANOVA alternative with 10 independent dichotomous variables

I am looking to pick an appropriate statistical model to generate an output similar to the ANOVA hourly wage example in https://en.wikipedia.org/wiki/Dummy_variable_(statistics). However, in my case: ...
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Kendalls u-coefficient to calculate overall consistency of pair comparison experiments

I have 8 conditions. In a pairwise experiment, I am comparing 28 pairs: condition1 vs condition2, condition3 vs. condition 4, condition1 vs condition3, condition4 vs, condition2, etc etc. Each ...
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What test should I use with a non-normal distribution?

I'm working in a small project but I've a problem trying to choose a statistical test to use. I want to contrast the fetal death rate (Total fetal deaths/Total pregnancies) between 4 regions of my ...
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Different (Welch's) ANOVA tests and post hoc contradict paired tests. Which one to accept?

This is a problem that I think nothing would help but sharing my data here. I have 3 groups (n=7) which are paired. They are concentrations of a chemical compound in different parts fish tissue. For ...
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98 views

How to simulate data for generalized estimating equations (GEE) with logistic link function?

I am working with a pre/post test structure, measuring dichotomous outcomes. I am using GEE to estimate the coefficient for time (also a binary variable, 0 representing pre and 1 representing post), ...
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43 views

Are the results of my paired tests false positive?

I am dealing with a strange situation which I hope you can come up with a solution. I have 3 pared group(n=7 for each) which I tried to see if they are significantly difference and if so, in which ...
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Which test should I use to compare two binomial variables measured in same subject?

For example, let's imagine I measured two binary variable in my subject: 1) SUV or not SUV, 2) Speeding or not speeding (similar to a 2x2 contingency table). Let's say I hypothesized that SUV are less ...
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Paired t-test with weights

I have $n$ pairs of observations $(x_1,y_1), (x_2,y_2)...(x_n,y_n)$ where each observation is itself the average over an underlying population: $x_1 = 1/N_{x_1} \sum_k x_{1k}$ $y_1 = 1/N_{y_1} \...
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77 views

Paired sample t test normality violation

I would like to conduct a paired sample t test and thus, I'm checking for the assumptions of normality. Upon conducting normality testing, each group scores were found to be normally distributed ...
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Testing the difference of means of varying indirect measurements

I want to find out whether the means of $log(A)$ and $log(B)$ differ. However, instead of sampling $A$ and $B$ directly, I could only measure $c_1A$ and $c_1B$ in one experiment and $c_2A$ and $c_2B$ ...
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What is the appropiate Non-parametric test for study with 3 conditions?

The IV has 3 separate conditions & the DV measures Pre & post scores (ultimately to see what condition has the biggest effect on the scores - if there is any). The data is non-parametric- ...
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Mixed effect model for data with paired/unpaired data

I have tested individuals on the number of parasites (ranging from 1 till 3) they have. For each parasite I described the severity of infection (ranging from 0.5 till 3). As an example, here a part of ...
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16 views

How do I compare two growth rates in a meaningful statistical way?

I have two growth rates (and also their corresponding levels) of two different groups for the same time period. I would like to show that: 1.) the growth rates were about the same for a specific month ...
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41 views

When to use raw (not relative) change vs. absolute change in a T-Test?

Suppose I have students 1 through 100 predict their test scores prior to taking a test. After the test, I record their actual scores, so that the head of my data table looks like this: ...
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24 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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1answer
19 views

Comparison parameters in panel data regression

I have two panel data. The first data is on cities on the period 1990-2000. The second data is observations on the same cities, but from 2001 to 2010. I want to estimate a model like this for each ...
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Would you consider this for paired analysis?

I've been having some heated discussions about whether this scenario using a cell line (passaged over and over) constitutes a paired analysis or not. By this point, I thought it was wise to ask the ...
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51 views

Regularized regression with dependent data/cases

I want to estimate a regularized lasso regression model using nested cross validation to determine the best lambda and to get an estimate of internal validity. Specifically I have a binary outcome (...
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210 views

How to deal with ties when conducting Wilcoxon signed rank test?

I have a paired data with a small sample size of 21 and I'd like to conduct Wilcoxon signed rank test using R. wilcox.test from the base stat package gives results ...
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Independence test informs paired difference test in matched pre/post settings?

I have a, perhaps faulty, intuition that if a paired difference test (e.g., Wilcoxon rank sum, t-test) for a pre/post item looks significant, one should use caution in interpreting this fact if an ...
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Should I calculate RSS using regression of identity line instead of Estimated values?

I have two paired datasets, one of them has linearly increasing ground-truth fat values (let's call it Ftrue) and the other has fat estimation values trying to guess the first ones (call it Fest), ...
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Paired t-test or Wilcoxon signed sum rank test for a slightly skewed data with a small sample size of 21? [duplicate]

I have a paired sample data with n=21. The two values V1 and V2 are from two different time points for the same group. I want to see if there is any improvement/reduction in values at time 2(V2). Of ...
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Comparing multiple independent distributions from two data sets

I am trying to find the best way to quatitatively compare two data sets. I would like to compare the width as well as the centroid of the distributions from the two data sets. Since there is many ...
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147 views

How to interpret pairs plot in R?

I am a beginner in plotting/graphing. Kindly explain how to interpret the pairwise scatter plots generated using pairs() function in R. The data contains 323 columns of different indicators of a ...
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Is there a way to estimate the minimal number of pairwise comparisons required to place complete ordering over a set of items?

I have 200 items that I need users to compare. If there are 2 items, A and B, then the comparison is A before B or B before A. ...
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Can the dependent samples t test be used for this problem?

Short story: I have 2 sets of data: Set 1: Daily data of stock market returns (eg. [1%, 1.2%, -2%]) Set 2: Those same stock market returns, multiplied by a number (eg. [2%, 0.6%, -1%] which equals ...
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Paired data comparison: regression or paired t-test?

Question I always used a paired t-test or a wilcoxon signed rank test (of course depending on the dataset) to check whether two methods (on average) yielded the same results. After learning more about ...
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Need more understanding on Paired T test result

There is a sample of people on which a medicine has been applied to treat mental illness. An attendance sheet was maintained everyday to see which patient is coming to the hospital. After few weeks ...
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1answer
57 views

Comparing repeated-measures means with unequal number of datapoints per condition

I have data from a study in which subjects were listening to a musical piece and asked to press a key at certain moments. The time axis has been segmented into adjacent epochs of time (of varying ...
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1answer
143 views

Testing for significant difference between coefficients from 2 different IV regressions (Stata or in general)

I'm running two different IV models in Stata that share the same DV and controls but have different instruments for the independent variable of interest. ...
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Why the degree of freedom is NA ? And why the p value is calculated when the df is NA?

I used R to do the statistical analysis. After running a glm model, I used Anova function to look at the p value for each explanatory variable. So far, everything was normal. However, when I used ...
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Paired sample t-test equivalent for intensive longitudinal assessments

I am a bit new to multilevel and mixed-effects modeling. I have a dataset, where I have sensor measurements throughout the day for 4 weeks on N participants. I have some prompts on their smartphones ...
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Assessing correlation between paired count data

We are attempting to compare paired animal count data from video and field observations. The video was collected at the same time as the visual field counts. We have three observers: ObsA: ...
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Meaning of this scatter plot

I have two types of treatment, a and b, and I want to know if one is more painful than the other. I can apply both treatments to each patient, and ask for the pain experienced with each on a scale 0-...