Questions tagged [paired-data]

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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Correct approach for paired Wilcoxon test

I have a 5 Likert Scale rating for 30 stories and for 30 altered versions of those stories. I want to compare these, so I want to do a paired Wilcoxon test. My problem: I now have a different number ...
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Statistically compare two algorithm outputs

I want to test the efficiency of two different algorithms. I have two random samples from the same population. On one sample, I run Algorithm X; on another sample, I run Algorithm Y. There are 30 ...
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Regression with paired repeated measures design

I have the following data: ...
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How to adaptively select stimuli in paired comparison experiment?

I have 500 items of which I want to know how much they are liked by a specific expert. To find how much they are liked, I wish to use paired comparisons since this yields more accurate results than ...
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Mixed effects model for paired subjects in a complex design

I'm new to the mixed effects approach and I'm struggling to understand how to apply it to my relatively complicated experimental design given that all tutorials and articles I read are not directly ...
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Can I conduct an exploratory cross-over study on data originally collected in a clinical trial?

I need your opinion about this study. Originally it is a clinical trial comparing two treatment regimens (of IVF) on the chance of fertility. One (Treatment A) consists of ovarian stimulation during ...
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Is it always appropriate to convert paired data to unpaired data?

This is a general question, which I have encountered regularly, but as it is seemingly very basic, I can not seem to find an answer / explanation for it. Assume a situation in which we have paired ...
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What type of analysis to use for a pre-post test design with paired means and covariates (stata)

I am conducting a retrospective analysis of the efficacy of an intervention with "Therapy A." There is a baseline period and a treatment period, however, all the patients received the ...
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If the difference of scores is normally distributed, the sample distributions don't matter in a paired t-test, right?

I have a very straight-forward question: If the difference of scores is normally distributed, the sample distributions don't matter in a paired t-test, right? Therefore, If the samples are not ...
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I run a paired t test one tailed. Shapiro results not nornal. Rank test too.Also other non parametric test do not meet the critetia. What should i do

What should I do if my normal distribution do not meet the criteria and other non-parametric tests too? How can I report it? Also, should I still keep these variable which are not normally distributed ...
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How to apply the t-test to data with multiple observations per pair

Imagine I collect time series data from a group of people before and after treatment. Now if I want to compare the results before and after should I take the average of the time series and apply a ...
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is it statistically correct to combine paired and unpaired samples together and perform tests?

I have samples from left hand and right hand of same individuals (11 patients, 22 measurements) and left (4) and right (2) hand from different individuals (6 patients, 6 measurements). Is it possible ...
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Discrepancy between correlation coefficient and paired test result

Is it possible to be significant in paired t test for the pair with correlation coefficient of 0.96? total n = 350. correlation coefficient = 0.957, 95% CI 0.947-0.964, p.value = 1.48e-210 First ...
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Comparisons of two ordinal paired data in many subgroups, all of which are then compared to that from one reference subgroup

For a subgroup of age 18-50 (‘age’=1) and normal kidney function (‘egfr’=1), I would like to compare 2 diagnostic classifications of a heart disease (‘hd1’ and ‘hd2’) categorized into 3 stages (no-...
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What are the benefits of designing paired vs unpaired clinical experiments

I would like to know what additional information one can obtain from paired vs unpaired clinical data? Why one should prefer one design over the other one? My second question, imagine I run two ...
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How to reduce the number of observations (rows) by keeping the most unique (less redundant) ones

Although not a very common usecase, I need to select a subset of observations that withhold the maximum of the total variance of the dataset. In other words, I would like to remove rows that are "...
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how to compare percentages of intervention group before and after interventions? (repeated dependent variable are presented in categorical variables)

I am conducting a randomized controlled trial, and after intervention, the numbers of patients with some characteristics (for example, prediabetes or IGT) have changed. I want to compare the ...
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comparing paired data between two groups

I collected 30 cases of paired data which includes serum creatinine before&after taking specific medication. And the cases are divided into two groups A and B each of which has different medical ...
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Should I normalize returns when performing a paired t test?

I am trying to see what trading strategy is better with back testing. The data is The daily FX rates from the last 20 years. However, each of the 2 strategies generates different entry/exit signals, ...
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Paired, discrete hypothesis testing

I am facing the following situation. I asked my class of 19 students to rate their interest about a certain topic on a 1-5 (discrete) scale. I then spent some time teaching them about this topic for a ...
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Special scenario when the same participant acts as both the control group and the experimental group scenario, but at the same time

I would really appreciate any advice here on if there are any special parameters I need to use for this example. I am looking at the effect of an analgesic on pain level after ocular surgery. Both ...
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Rank Correlation for Paired Predictor to compate 2 GLM models: appropiate objects and p-value

Dear Professor Harrell and users, Thank you for this post: How to assess the incremental additive information of a new predictor in a Cox model using R?, it has been really helpful for my work. I am ...
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What statistic should I use when I have two devices measuring 20 different samples over three days?

I have two measuring devices that I use to measure 20 samples over the course of three days. Each device produce 3 measurements per day. As a result, I have nine values per device per sample. Please ...
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Get statistic about cancer after radiotherapy

I have 100 patients all with specific benign tumor. They have radiotherapy and removed tumor. Some of them have secondary cancer after more than 15 years. Our question is, what is a probablity, they ...
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Meta-analysis of paired count data

I have data from 70 studies reporting number of observed events in two time periods, one before Covid and one during the Covid pandemic. The duration of the timeperiods and the size of the population ...
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Repeated misures for 4 level outcome

What is the correct test to evaluate the difference between 3 RX readers of the same 50 patients? The rx outcome is a categorical value with 4 ordered levels. The 3 reader have read the RX at the same ...
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How to adjust a covariate in a paired Wilcoxon signed-rank test?

I am trying to study the difference in a biomarker (ANG7) levels pre and post bariatric surgery (a weight-loss surgery). I am using paired Wilcoxon signed-rank test ...
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paired t-test for data with large variance

I'm making a research plan, but I don't know how to solve the following problems because I don't have enough statistical knowledge. Can I get some help? Assumption: let's assume that the red line in ...
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Is a paired samples t-test suitable in this case?

I have 3 tasks and want to find out which one is more effective (that is, to find which task people performed better in). Just over 30 people have participated in all 3 tasks, and their performance ...
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Paired sampling in Machine Learning?

In hypothesis testing, it is sometimes beneficial, if possible, to perform paired sampling - where pairs of observations come from the same source, say before and after some intervention. As I ...
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Remove the effect of an unwanted independent variable (binary) on a dependent variable (continuous) in a paired test

Is there a way to remove the effect of an unwanted independent variable (binary) on a dependent variable (continuous) in a paired test? I have 40 subjects, each one performing the same task with two ...
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Change paired t test to LMM: while the content tested before and after treatment is different

I'm new to linear mixed model. I'm not sure how to use it if the contents of pre and post test are different. It's a within-participant design, including two sessions (with treatment and without ...
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How to compare variables with data from multiple experiments?

I have an experiment in which i compare the amount of attached bacteria in three different conditions. I have repeated this experimented three times, so now i have three datasets with the same data (...
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Are my data paired or not paired for a t-test?

I am analyzing data where my experimental design is as follows: DNA and RNA samples were taken from 3 mesocosms at seven time points across the duration of the study to see DNA and RNA decay across ...
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Kruskal-Wallis versus Friedman - Paired data, but not repeated measures/blocks?

I'm trying to compare the difference in behaviour of an animal with no enrichment to the same animal with two (or more) types of enrichment. (Total active behaviours before/total active behaviours ...
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Identifying statistical significance of improvement due to treatment

Consider an experimental setting where the universe of elements (eg. webpages) to measure $U$ are split randomly into two equal sized groups, a control group $C$, and an experimental treatment group $...
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Which test can I use for comparing two reaction times taken from the same group that are not normally distributed? Instead of paired sample t-test?

I will conduct a study in which I compare the reaction times (acceptability judgement) to two different types of sentence. I am assuming that scores will be normally distributed and I will use paired ...
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Compare Paired Data from 2 Timeframes of Different Lengths

I need to compare dependent samples (matched-pairs) from the same group in 2 time frames, simply a hypothesis test to determine if there is any statistically significant difference pre and post an ...
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How to form the hypothesis and which statistical test to use when we have before-after data of two individual groups?

So basically I have medical data where the data is collected from two different treatment groups and various variables are measured for individuals in the two groups. Data was measured before, during, ...
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Account for different amount of observations per participants without using a regression approach?

I am trying to figure out the statistics of a study where I have 60 participants with varying amounts of observations per participant. I am measuring facial muscle activity after a button press over a ...
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Jonckheere-Terpstra test for DEPENDENT samples with an ordered alternative hypothesis

I have a question about the tests that consider an a priori ordering (the alternative hypothesis is ordered - testing the hypothesis u1 ≤ u2 ≤ ... ≤ un). We want to compare a variable in the same ...
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Paired t-test vs two-sample t-test - animal populations

From my understanding, a paired t-test is used when samples are dependent of each other. I'm having trouble deciding whether a paired t-test should be used when comparing the average population of a ...
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2x2 contingency table with some data-points paired and some independent

There are two items in a task (item A, item B). On each of the two items participant can score success (1), failure (0), or not provide a meaningful answer (NA). Participants with NA on both item are ...
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3 Paired Datasets Hypothesis testing

n = 72 subjects were randomised to 3 treatment groups: A, B, C, such that n = 26 for Group A, n = 29 for Group B, n = 17 for Group C. Measurements were taken before and after treatmentThe differences ...
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hypothesis testing depending on the distribution of the data

I have a paired dataset where the before-treatment observations are non-normally distributed (Shapiro-Wilk test p-value = 0.007) and the after-treatment observations are normally distributed (Shapiro-...
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What statistical test / analysis should I use?

I have conducted a RCT with two arm treatment. I would like to compare the difference on an 8 question pain scale between groups. Data has been completed at baseline and every week for 5 or 6 weeks ...
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Should paired data correlate when using paired samples t test?

I have repeated measurements from a usability study on 2 different interfaces (n=23). Since the difference between the measurements seems to be normally distributed I used paired samples t-test to ...
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Meta-analysing impact of Covid pandemic on risk for perforated appendicitis

I am analyzing the impact of the change in the management of appendicitis during the covid pandemic. I have paired data from 31 reports comparing the number of operations for perforated and ...
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Compare paired before and after composition proportions

I have some data on the composition of purchases by households, before and after an intervention. This composition is known at the number of items or amount spent level within 7 categories, and can be ...
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Wilcoxon Signed Ranks Test for relative differences

Is it correct to use the Wilcoxon signed ranks test for relative differences $\frac{Wx-Wy}{Wy}$, instead of absolute differences $Wx-Wy$? In some cases the relative difference is more relevant, for ...
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