# Tagged Questions

Paired data arise when the same subjects are measured in two different conditions, so that for each individual subject there is a pair of measurements. A paired t-test is a widespread example of a hypothesis test for paired data.

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### Can an independent t-test be used on paired data when the pairing is unknown?

Suppose the effectiveness of a training course is examined, and performance of each individual in a group is taken both before and after, and the differences are compared in a paired $t$-test. Would ...
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### Paired independent sample t-test?

I have two methods of processing certain data, where one is a more advanced version of the other. After processing the data, the output is scored from -1 to 1. I have a set of 7 distinct data points ...
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### Weighted, Paired-Sample T-test? in R [closed]

In R you can run a paired t-test (e.g. t.test(x, y, paired=TRUE)) as well as a weighted t-test (e.g. ...
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### Paired or non-paired data? comparing two sets of scores from same individuals

I have data from four companies, W, X, Y and Z. For each company, three groups of 5 individuals (15 individuals total) take part in a test. Every individual takes two tests, test A and test B, with A ...
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### How to show that one series of observations are faster that another series for them same task statisitcally

Hi I have a dataset consisting of two series of observations (times to reach a goal) of users performing a task. Each observation is paired with another one in the other set representing exactly the ...
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### Correlation of two categorical variables

I have a list of N people, with two equivalent test performed (A and B), which can have as outcome 0 or 1 (cancer positive or negative). Test A is the accepted gold standard. Is there any way to find ...
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### Comparing mean test scores (different tests, same group)

I have the following problem: There is 1 group of students (student 1, student 2, ..., student n) This group of students takes several tests (math, French, Biology) - all scored as percentages ...
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### What statistical test is appropriate for paired data where the same subjects are tested at multiple times?

In the test in question, we have data [measurements of discomfort] for the same subjects with different virtual reality experiences. We took multiple measurements of discomfort over the course of the ...
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### Pair t-test or Welch's t-test on a non-normal data series?

I have rainfall time series of 85 points from 1901-2013. I want to check whether the mean rainfall during 1901-1970 is significantly different than that of the mean rainfall during 1971-2013. Here, ...
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### Difference between paired t-test and repeated measures ANOVA with two level of repeated measures

Would paired t-test and repeated measures ANOVA with two level of repeated measures on the same data give the same results? I ran a few tests and realized that their p values are the same. Does mean ...
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### compare two 2D-datasets

I have measured 7 analytes (chemicals found in blood) from a patient, before and after treatment with some drug. These analytes' levels in blood are affected (increased) by drug treatment. The blood ...
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### Is this simple paired-sample permutation test valid?

I have about 10 pairs of scores, $(x_1, y_1),~ ...,~(x_{10}, y_{10})$, with all $x_i$ and $y_i$ being between 0.0 and 1.0. I'm interested in testing whether the mean difference over pairs is ...
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### Regression analysis for paired data in SAS

I want to analyze paired data using regression analysis to adjust for covariates. I used PROC MIXED statement in SAS and I modeled the difference as the Y in the ...
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### How to compare the change (increase or decrease) for two pairs using one-way Wilcoxon signed-rank test?

Suppose I have $X_{before}$, $X_{after}$ and $Y_{before}$, $Y_{after}$ (before and after the drug). Each variable have 15 observation, i.e 60 in total. I used one-way Wilcoxon signed-rank test to see ...
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### Paired Likert Data - Pairing was lost

I was given some likert type data (5 ordinal response possibilities) from a pre and post assessment so the data is paired. However the pairing of the pre and post data was not kept, so I do not know ...
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### Statistical test for paired data in an r x c contingency table

To perform statistical test on paired data when we have two dichotomous nominal variables (i.e., in a 2 x 2 contingency table) we can use the McNemar's test. When ...
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### ANOVA - Independence condition for paired data

Hi I'm reading the book "OpenIntro Statistics" about ANOVA and in section 5.5.4 when explaining the conditions for applying ANOVA under the voice 'Independence' it states: Independence. [...] For ...
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### Statistical analysis for interaction of genes in multisamples

Say I have 120 human individuals. I have done gene-gene interaction in those individuals and found the frequency of all the interacting genes as shown in the data below. I want to do some analysis to ...
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### Paired test (non-independent) for rank order data

I have responses from a survey with questions where respondents were asked to rank their top 3 choices from a list of 8 choices. An example of the type of question would be to rank their top 3 methods ...
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### Between-subject comparison contains paired data

This is a difficult question to search for, so I apologize if it's been addressed elsewhere. If I am interested in the effect that weather (sunny/rainy) has on dog running speed, and I have running ...
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### Paired test, unknown sample identites

I have data in which I have repeated measures on samples (at different times), but do not know the identities of the individual samples at each time point. Just for some context, I'm doing behavioral ...
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### Can a paired t-test be used with the number of words recalled?

I recently went to a 3rd grade level science/math school exhibition, where someone had posted this data on how well people remember words, when they read it in a book vs a tablet. There were in total ...
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### Test for variance homogeneity and dependent samples

I have the following question regarding statistical tests for an fMRI phantom (i.e., roughly speaking a standardized object (e.g. cylinder filled with gel) used to make inference e.g. on properties of ...
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### Difference in Means vs. Mean Difference: Confidence Intervals

This is a follow-up question to Difference in Means vs. Mean Difference. I am, however, interested in the confidence intervals for the difference of the means, and the mean of the paired differences. ...
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### Testing similarity between paired measurements compared to population

Suppose you measure heights from sets of two siblings and want to test if siblings are more similar to each other than to the population as a whole. What would be an appropriate statistical test?
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### Power calculations with a continuous independent variable in a case-control study with pair-matched data

So I have been struggling with this matter quite a while now and still have not found a solution to this problem. In fact similar questions have been asked here before but no answer was provided to my ...
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### Can you do a paired t test in online calculator using only mean and SD?

I have only the MEAN And SD no data
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### Paired t-test and correlation

Say I have $n$ pairs of observations. I can run a paired t-test to test for the significance of the difference in means. I can also look at the coefficient of correlation between the 2 sets of ...
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### Effect size and bootstrapping in paired t-test

I have multiple paired $t$-tests, such as one giving results: $t_{14} = 2.7,\ p = .017$ Although people seem to do effect sizes in different ways in repeated samples, I have taken the mean ...
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### paired t-test, 2 samples of different sizes

I have a population of interest on which one numeric variable has been measured twice: before and after surgery. I did a paired t-test to compare means of the variable. However, there is a difference ...
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### Statistics test for paired data with discrete outcomes

I have pre-post data for several variables and I'm looking to analyze them. The responses to the questions are 0,1,2,3,4 with 4 being best and 0 being worst. For each variable could I simply find the ...
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### Interpreting wording for formulating hypothesis testing

I've been presented with paired data for individuals' weights before and after a dieting program (paired t-test problem). The question being asked is "test the hypothesis that the dieting program is ...
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### Should I use two-way ANOVA or some kind of paired t-test to compare response to treatment?

I have browsed around and have found mixed partial answers so I decided to give my exact situation and see if you guys could help me (really appreciated). My data has 3 columns: Before treatment ...
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### Stuart Maxwell on 3x3 contingency table or collapsing of 3x3 to 2x2 for McNemar

I have a 3x3 table of paired data (current,former,never) which is compatible with the Stuart-Maxwell or even the Bhapkar test but all of the studies I've seen working with similar data collapse the ...
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### Mining sequential associations using entropy measures

Assume I have a sequence that looks like this: A-A-A-B-A-A-C-A-A-B-C Let's say I want to predict to use the sequences of letter that occur between one letter and ...
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### Compare between two dependent but not paired samples

I want to compare the mean of two samples. Sample A is for one day and Sample B is for one week. Sample A is a subset of Sample B, that is, the week in Sample B includes the one day in sample A. It is ...
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### Statistical test for one paired observation [duplicate]

In this question, @whuber writes in his reply that If you were willing to assume something about that common distribution (such as it is some Normal distribution--but without knowing or assuming ...
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### Paired design and building a GLM

I am blocking a bit on the choice of a model for my data. The study is applying 2 different stimuli (S1 and S2) on some animals. Each stimuli has two 'treatments': either 'on' or 'off' (off being the ...
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### Computing required sample size for paired t-test

I have some paired t-test data (40 pairs) and I would like to use these data to estimate the sample size required if I were to conduct the study again with a new set of requirements. I'm using ...
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### Testing the difference between multiple paired proportions with different sample sizes

Is there a hypothesis test similar to the paired t-test for testing if the difference between a number of paired proportion estimates is significantly different from zero? The data consists of 2 lists ...
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### What's a good way of graphically representing a very large number of paired datapoints?

In my field the usual way to plot paired data is as a series of thin sloping line segments, overlaying it with the median and CI of the median for the two groups: However, this sort of plot becomes ...
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### compare data for self, ideal self and imagined self

I'm trying to compare data for an actual, ideal and imagined self, data was obtained by asking participants to fill out a BFI questionnaire three times, once for each self. The more I think about ...
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### How can I find out the needed sample size

I'm going to study if medical reconciliation diminishes the amount of inappropriate medications amongst elderly people in a small part of Sweden. I will count the number of inappropriate medications ...
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### Comparing logistic regression models with paired data, population-averaged estimates and robust standard errors

I would like to ask if any of you have suggestions for comparing logistic regression models with paired data (3 observations/ID code), population-averaged estimates and robust standard errors (I am ...
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### Overlapping or sliding interval matching

So I want to conduct a matched case-control study. One of the variables I want to match on is continuous variable, lets say age. I have converted this to categorical variable [17-19],[20-36],[37+]. ...
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### Difference in Means vs. Mean Difference

When studying two independent samples means, we are told we are looking at the "difference of two means". This means we take the mean from population 1 ($\bar y_1$) and subtract from it the mean from ...
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### What is a paired observation or paired variable?

The question kind of asks itself, can anyone explain what a paired observation or paired variable is in basic terms? My data consist of the number of words learnt in a week for 19 different ...
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### Fisher exact test on paired data

Given $40$ cases with lung cancer and $40$ matched controls (without lung cancer) (matching based on age, sex, etc.). To try to find evidence between the effect of smoking on lung cancer, I used ...
Say you have an independent variable, $x$, and two dependent variables $y_1$ and $y_2$. I want to calculate whether these two variables have a significantly different slope. I can do it by calculating ...
I've read that working with paired data requires other method than Mann-Whitney $U$ test. I am not sure about how formally accurate is this statement. Reasons: Suppose that there is a set of $n$ ...