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1answer
15 views

Are multiple paired t-tests among 2 groups safe and effective?

Part A: Suppose I have 2 groups (pre-treatment, post-treatment) and for each subject I record 3 variables. So my rows look like: ...
0
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0answers
33 views

May I treat two subject groups as if they were one when attempting to demonstrate the existence of an effect?

I have collected data from 88 human subjects. There is two subject groups, A (test) and B (control). Number of subjects in each group is 44. The subjects are paired between groups. There is two ...
2
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0answers
31 views

Can you combine z scores from similar but non-identical populations?

Suppose you have a group of people estimating the heights of trees. Suppose you have many different types of trees, some trees with a very low height, and others that are very tall. Suppose each ...
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0answers
33 views

Longitudinal paired analysis

I need your advice regarding a complicated design. I am testing data regarding new eye drops that suppose to decrease some quantitative measure. For every subject, one eye is randomly assigned with ...
10
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4answers
551 views

How can a t-test be statistically significant if the mean difference is almost 0?

I am trying to compare data from 2 populations to tell if the difference between the treatments is statistically significant. The data sets appear to be normally distributed with very little ...
5
votes
1answer
70 views

What is an “Unpaired Bland-Altman plot”?

I found this quote: Unpaired Bland-Altman plots were used to check systematic or bias errors in the SPECT myocardial uptake coefficients with respect to the reference standard PET data. ...
0
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0answers
47 views

Paired test: many repetitions, few subjects

I have a situation similar to this: 9 normal-sighted subjects are each tested under two conditions: say, with and without spectacles (of a fixed power) and asked to reach towards an object many times ...
0
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2answers
102 views

Alternative to multiple Fisher's Exact tests

I have count data for a pair of test and control populations of samples for a variable that takes a value of either A or B for a sample: ...
1
vote
1answer
44 views

When Should The Following Tests Be Run

What are the assumptions behind each of the following types of tests (i.e. what are the prerequisites to running each test). Paired-t Sign Two-Sample t Pooled Two-Sample t Two Proportions F I ...
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0answers
46 views

Writing R Function To Determine Which Statistical Test Should Be Run

I am trying to write a function in R that determines which of the following statistical tests should be run on a set of data: {paired-t, sign, two-sample t, pooled two-sample t, two proportions, F} ...
3
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2answers
65 views

Can non-paired data have dependency?

I have two vectors of data of different sample size. Both are the same experiment, but executed in a different environment. Since the sample sizes are different and they don't share any subject, is it ...
0
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0answers
35 views

Average difference in averages and t-test

I'm currently working with some individual level data and have run up against a wall in figuring out the best way to analyse it. Let me describe: We have a sample of N=9000 Physicians. For each ...
2
votes
1answer
137 views

Missing data SPSS paired samples t-test

I have approximately 20% data missing in my sample (n=3215). I aim to assess the pre-post differences on a psychometric scale. Especially post measures are missing because of follow-up issues. What to ...
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0answers
32 views

How to compute the probability that there is no difference between matched pairs

I am looking for a way to find the probability that there is no difference between a matched pair of binary data. I don't want to know whether the difference is statistically significant, I want to ...
1
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0answers
60 views

Reducing sample size to change from a paired to unpaired design

I have two groups of data, one consisting of 9 subjects and another consisting of 5 subjects. In the 9 subjects group, 5 of those could be paired with the 5 subjects from the other group. I could run ...
3
votes
2answers
274 views

Critical effect sizes and power for paired t test

Is there some sort of easy way to calculate the required sample size for a paired t-test with an effect size of 2 standard deviations? In my line of work, we often use an effect size of 2SD from the ...
1
vote
2answers
72 views

Difference AM-PM or PM-AM for a paired T-Test - to test if the mean of the differences = 0?

I have a paired set of data, that I wish to perform a t test on to test if the mean of the differences is equal to 0. I notice there is a difference between if I do AM-PM vs PM-AM - which way should ...
1
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0answers
123 views

Is it correct to use a paired t-test for this question?

this is an exam practice question for my 1st year stats class and I just want to see if I have approached this problem correctly and to clarify my understanding. Here is the complete question: A ...
1
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0answers
159 views

mixed effect model for method comparison of time series of paired measurements

A coworker and I are trying to analyze agreement between two measurement methods. I apologize in advance for needing some extra explanation due to the fact I'm an engineer whose statistics background ...
1
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2answers
75 views

Prey preference - can I use a paired t- or wilcoxon test?

I have done an experiment in which I looked at the prey preference of an aquatic invertebrate. I used 10 containers all with one predator but with different densities of prey. I used two different ...
1
vote
1answer
138 views

Paired t-test or Independent t-test

I am new to this forum so here goes. I have an assignment question I need help with. A scientist has performed some experiments to determine the relationship between the concentration of phosphorus ...
2
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0answers
283 views

Methods for comparing proportions in partially overlapping samples

We conducted 2 similar surveys in parallel to a group of health care facilities. One was sent to managers, one to staff. Some questions were identical, others asked about different areas of the ...
0
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0answers
66 views

method and needed tests for assumption in analyzing a paired sample Likert measure?

I am writing an exploratory paper considering an argument that a certain reaction that can arise in the viewing of art can serve as an empirical indicator that another particular cognitive process has ...
0
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0answers
260 views

Which test to check statistical relationship betwen paired/unpaired data?

I have data that is in-between of "independent samples" and "paired samples". About 50% to 70% of observations are matched (paired) and the rest miss a pair. Which test should I use - chi-square ...
2
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0answers
112 views

Random Forest or other machine learning techniques with paired samples

I am trying to select features from paired samples and was wondering if there are methods out there that adapt random Forest or other machine learning algorithms to paired samples i.e. if randomForest ...
1
vote
1answer
91 views

Can high quality clusters be found in every data set?

In my data I have 3 clusters with average silhouette 0.61 and very few negative values. I repeated k-means 10 times with k ranging from 2 to 10. This seemed to work ok, but the problem is that I got ...
0
votes
1answer
151 views

What paired test should I use and how do I interpret it?

The question: The data file contains observations of the wavelengths (in nanometers) of the main color in two kinds of shoe polish. (Sample size = 100). Are the wavelengths significantly different? ...
5
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0answers
222 views

Compare two survival curves for paired data

I want to compare two different methods for detecting status change in a survival analysis. A group of subjects is being followed for a longer period (many years), and two examination methods have ...
1
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1answer
331 views

Confidence intervals and pairwise comparisons

Let us say I have the following pair wise test data: ...
3
votes
1answer
1k views

Output of one-tailed Wilcoxon sign rank test in R

I'm trying to assess the difference between two algorithms. They are stochastic, so I've run them multiple times against the same input files and noted their results. I want to determine whether my ...
2
votes
1answer
136 views

Permutation paired test with signed statistic

I have one paired data from 7 patients: $$(X_i ,Y_i)=\{(5,1),(-2,-4),(4,2),(-6,-3),(-3,-3),(-5,2),(3,1)\},\quad (i=1,\ldots, 7)$$ where $X$ means placebo $Y$ means the test drug. My classmate asked ...
1
vote
3answers
346 views

Once again: paired versus unpaired t-tests

This is much the same question that I asked a few weeks ago, but I hope to explain myself more clearly this time. I start with 40 mice. I use my own scheme, based on my own ideas for how to make the ...
0
votes
1answer
313 views

Is there a statistical significance in my paired sample data after performing Wilcoxon signed rank test?

I have a paired data consisting of $N$ = 421 samples. I would like to find out if there is statistical significance between the paired samples. Since, I do not know the underlying data distribution I ...
4
votes
1answer
994 views

Why is my bootstrap function for paired samples t test in R not returning the same result as SPSS?

I want to verify using a bootstrap approach the hypothesis about a lack of the intervention effect within a group of six patients: pre-(X) post(Y) intervention measurement. My data ...
7
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4answers
6k views

Paired versus unpaired t-test

Suppose I have 20 mice. I pair the mice in some way, so that I get 10 pairs. For the purpose of this question, it could be a random pairing, OR it could be a sensible pairing, like trying to pair mice ...
4
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2answers
46 views

Which test to use to check for better ratio for matched participants?

I would appreciate if you can tell me which statistical test to use for the following data analysis: I have data from 10 people and 10 of their siblings. For each person and her sibling, I have two ...
0
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0answers
75 views

finding significant pairs in co-occurrence matrix

For a matrix $M$ in which entries $m_{a,b}$ denote the number of co-occurrences between elements $a,b$ from two distinct sets $A$ and $B$, how do I identify pairs with a significantly high ...
1
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0answers
151 views

“Paired data” / “repeated measures” in 2x2 experiment

I have test subjects answering questions, the data will be quantitative. The questions can be divided to four categories by two factors that have two levels. For each question a factor A, B, A and B ...
2
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0answers
141 views

Correct variance for minimum detectable difference

I have a question regarding variance, paired testing and minimum detectable difference (MDD). Paired samples: $$ MDD (δ) = \sqrt{ \frac{σ^2}{n} (t_{(α/2,n-1)} + t_{(1-β, n-1)})} $$ I have a set of ...
6
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1answer
2k views

Which model should I use for Cox proportional hazards with paired data?

I am hoping someone can help me with which model (frailty, strata or cluster) I should use for my data. I have paired data so I need to take that into account when modelling the Cox PH and am unsure ...
3
votes
3answers
990 views

Is Spearman's correlation coefficient usable to compare distributions?

I have distributions from two different data sets and I would like to measure how similar their distributions (in terms of their bin frequencies) are. In other words, I am not interested in the ...