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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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SPSS Paired Samples T-Test outcome interpretation

Hypothesis: -Blood pressure will decrease after intervention Results (blood pressure): Systolic bp before mean: 102.00 Systolic bp after mean: 97.10 Diastolic bp before mean: 70.80 ...
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What SPSS test should I use for blood pressure pre- and post-intervention for comparison?

I have 10 participants who consumed an intervention for 3 weeks. I would like to look at any significance between pre-intervention and post-intervention readings. What SPSS test should I use? I ...
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Paired samples with various ordering in observations, signed rank test?

I have a small number (10) of samples to analyze The idea is to measure the impact of two surgical procedures, A and B. In my population, I have people who did first A, and then B, and other people ...
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paired t test to compare means of proportions

I have 12 subjects. One Indipendent variable: word learning (2 levels: learned/not_learned) One Dependent variable: proportion of sound exemplars in the language heard by subjects (proportion ...
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Wilcoxon Test gives W=0

I am running the Wilcoxon Test on my data, however, I get a W value =0. My questions are two: 1): Why is the case such a test gives 0? ii): How to interpret such results?
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Wilcoxon signed-rank test for paired and repeated measures data

I have a dataset with 45 participants, each with 1-7 datapoints/observations (126 total observations). Each of these observations represents a window of time in which two different methods attempt to ...
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48 views

How to run paired t-test when number of control and treated experiments aren't the same?

I'm working in a biology lab and I treat some cells with a drug (treatment) or untreated (control), then transplant them into mice. Each experiment starts with the same cells (being exposed to the ...
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29 views

Pursuing meaningful questions about pre- post- intervention outcome measures in single condition treatment

If you are not fortunate enough to have a control group and have a single condition only, what meaningful questions can you ask about the change in pre to post intervention scores? If ANOVA or ANCOVA ...
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Paired $t$-test with multiple values

With the following data, I believe the difference in performance between two athletes can be measured with a (one- or two-sided) paired $t$-test: ...
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Paired Wilcoxon signed rank test-compare median

I have been comparing driving behavior before and after a technological intervention for a specific group of people. My data is far from normal hence I have used paired Wilcoxon signed rank test. If ...
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57 views

Can a Wilcoxon signed rank test be applied on dated data?

I have data for military male and female orders for types of clothing purchased from 2012 to 2018 (below is a very simple example - most of the data is one item purchases). If I look at one type of ...
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Does it make sense to include a *time-invariant* covariate in a simple pre-post analysis?

Background All participants were subjected to a single intervention and a questionnaire was issued before and after the intervention. This is a simple pre-post design. Question I can analyse these ...
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Permutation tests for paired data with several variables

I am trying to answer my own previous question, with a permutation method. I have a reference method $M_{ref}$ that I would like to compare with other methods $M_1$, $M_2$, $M_3$ when taking ...
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Paired variables?

In our research on apprenticeships in early modern times, we have a series of observations (cases), each with several variables. Each observation is unique because of its combination of the variables "...
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Are there any statistical tests or measures for paired data with more than two groups?

Are there any statistical tests or measures for paired data with more than two groups? My dependent variable is pretty flexible, but I'd really like to have five independent variables compared ...
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How many pairwise combinations is possible?

I have a dataset regarding a natural language problem that am tackling with machine learning. My goal here is the generate training samples for one of the classes. I do this by doing pairwise ...
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how to combine Paried t test and multilevel regression in R

I want to compare the difference between two conditions (fed or fasting) for 15 participants, but I have two runs for each participant. I can average the two runs for each participant and do a paired ...
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Algebraic Manipulations in Mann-Whitney-Wilcoxon Test Statistics

Given Let $\Delta > 0 $ be positive real number. Consider the Wilcoxon-Mann-Whitney upper tail test $H_0: \Delta \leq 0 \,\,\, \text{vs} \,\,\, H_a: \Delta > 0$ aimed at testing the difference ...
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Trying to do a paired t-test but one variable is not normally distributed, log transformation did not work

I am trying to do a paired t-test but one of the variables is not normally distributed (vegetarian enhanced), as you can see from the boxplot. I tried to do a log transformation but it made the p ...
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How do you perform Wilcoxon matched-pair sign-rank test in Stata using a grouping variable? [closed]

I'm performing a diagnostic method comparison study in which I have 2 groups; one assessed using the experimental method, and one assessed using the standard method. These groups are matched, with 3 ...
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1answer
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Help with calculating number of animals for a fetal surgery experiment

Rather odd question. I'm a surgical resident who is currently a research fellow in a lab studying fetal surgery. Our plan is to test a glue which we believe will help seal a uterus after we open it to ...
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51 views

Proof that the pooled sample variance is biased when paired comparison is not used when it should be

Given the model for what is meant to be a paired comparison design: $y_{ij} = \mu_i + \beta_j + \epsilon_{ij}$ $i = 1,2; j= 1, 2, ..., 10$ Eg. An experiment comparing the different in mean hardness ...
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Comparing 3 groups at 2 time periods

I'm analysing a dataset and comparing three zones at two points in time. The data in question is: Hourly sightings of wild fish (CPUE) In one of three adjacent zones (A, B, and C) During the ...
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Applying Cliff's delta to paired data

Wikipedia provides a few ways of calculating Cliff's delta - an effect size quantifying distributional shift. However it only talks about having 2 samples that are unpaired. While one can apply the ...
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Comparing changes in pre-post count results for two cohorts

Thanks in advance! I have a pre-post analysis Of cases and controls. The outcome variables of interest are emergency room visits and hospitalization visits - both rare occurrences with median = 0 ...
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Clustering for pair-wise data

I have been looking for algorithms in Python to create clusters from pairs of data. The data structure is similar to the stackoverflow post: An algorithm to create clusters from data pairs in python, ...
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Should I use a paired sample t-test to compare two methods of measuring absorption lines?

Background I'm doing a research project in astronomy and measuring equivalent widths of absorption lines using Gaussian fits from a star's spectrum in order to determine the star's chemical ...
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Comparing survival rates

The question I have is focused on comparing remission rates at a fixed point in time. For example, I have cancer type A and cancer type B (the two are not mutually exclusive groups) and all patients ...
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44 views

Which statistical test to use? Not really paired, not entirely unpaired

I am setting up an experiment where I would like to determine whether there exists a difference between the participants' average self reported mental effort in some condition A and condition B. The ...
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Regression on a change between a variable before and after?

In my dissertation I am using a paired sample t test to see if there is a statistically significant difference between consumers' intention to purchase from and attitudes towards purchasing from a ...
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Power of the test

How can I calculate the power of paired t-test if the null hypothesis mean is equal to 0. With a standard deviation 0.0373, sample size n=12 and alpha 0.05.?
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123 views

Is this an appropriate use of a paired t-test?

I want to compare multivariate gene expression data (1000s of genes) from two different conditions. I have three samples from each condition and the samples were collected in pairs on three different ...
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21 views

How to derive SD from difference in means in paired data?

I am doing a meta analysis, so I am collecting data from manuscripts. I need to obtain the mean and standard deviation for timepoint 1 and timepoint 2 for a variable called mpg but the paper only ...
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1answer
65 views

Paired t-test following main effect of mixed model with missing data

I am analyzing data for a repeated measures study with missing data. For example here is a 3 X 3 experimental design with three conditions and 3-time measures: I am using a mixed model for the main ...
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Comparing the subgroup to the group

I would like to compare the demographics of a total cohort of patients to a specific subgroup to see if there are differences. Since the subgroup of patients is included within the total cohort - what ...
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106 views

Mixed model applied to transformed data, or paired t-test applied to subject-medians of untransformed (skewed) data?

I am attempting to find the most appropriate way of analysing a set of skewed data, and I'm torn between two different approaches (each approach appears to offer its own advantages and disadvantages). ...
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1answer
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Use paired t-test to compare mean scores of 2 interventions, if 1 group got only 1 and another got both?

Let's say there was an intervention delivered using method A and method B. There was a post test asking participants about satisfaction on a Likert scale immediately after each method was delivered. ...
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Wilcoxon Signed Rank Test in Python (Reporting Siegel's T vs W?)

While using the Wilcoxon signed rank test in scypy over a subset of populations, I noticed that my test score was reported as zero for an array of differences whose distribution of medians is heavily ...
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Correction for different number of sampling days with individual samples for paired t-test

I have pre and post-fire data from GPS collars. Unfortunately, not all animals were collared at the same time and none of the animals were collared any more than 25 days before the fire. For each ...
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Alternative test to paired t-test? [duplicate]

I need to compare data from paired groups, but my distributions are non-normal, and my sample size is small. Are there any tests I could apply? I've been looking into non-parametric alternatives like ...
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12 samples, split into 2, 68 variables measured; 68 paired T-tests?

I collected blood samples from 12 patients. Each sample was split into two different storage vessel (24 total aliquots). All 24 aliquots were analyzed for 68 elements. Since the patients are selected ...
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merit of t-test vs repeated measures

In a cohort study, patients have been enrolled for a new method of treatment of a condition. The measurement of interest, for example, tumour size is taken at baseline (BL) ie before treatment, the ...
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26 views

Kolmogorov Smirnoff test result vs paired t-test result

I have a set of medical data which contains two samples taken in different time periods. Although the samples do not strictly contain the same people in each group, a large proportion in each group ...
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Before and After mean difference with positive and negative changes

I have a table of data. Column 1 Before Column 2 After In some cases the After values are larger than the Before and vice versa. If I calculate the difference between each Before/After pair some ...
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1answer
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Comparing the results of 2 different type but identical samples from 2 devices

I have 2 columns of of the concentration of fat in fish which is measured by 2 different labs. I need to know if the difference of the results from these 2 labs are statistically significant. The data ...
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1answer
220 views

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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45 views

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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1answer
54 views

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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604 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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Dependent variable as MEAN of proportions- treat as continuous?

I have two dependent variables, one is a mean percentage and the second is a mean duration. I understand that if your dependent variable is a proportion, you cannot treat it as continuous, for example....