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11 views

One way ANOVA: post-hoc comparison “adding letters to graph” [migrated]

I am working on a project for one of my classes and cannot figure out how to obtain the letters for treatment comparisons after using the tukeyHSD post-hoc test. Is there a simple way to do this? ...
0
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2answers
25 views

TukeyHSD multiple comparison on binomial data using Multcomp package in R

My question is how to perform TukeyHSD multiple comparison on ratio(for example, conversion rate, graduate school admit rate) using multcomp package in R. Take UCLA admission data for example: ...
1
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0answers
5 views

Compare non-gaussian distributions and evaluate sampling process

I have a 150,000 datapoints (continuous values between 0 and 1) and I am running a process that averages groups of smaller samples based on some other data values and results in ~100,000 datapoints. ...
4
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4answers
102 views

Paired t-test when each data point was repeatedly measured different number of times?

I have an existing data set that comes from the same group of people before and after they received a treatment. The data set comes from when participants tested their blood sugar values over a 30 ...
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0answers
12 views

When to plot different slopes for different treatments in ANCOVA

I am running an ANCOVA with a treatment of 3 levels and a continuous co-variate. Using step() in r, the simplest model includes the treatment factor and the co-variate, but not their interaction. To ...
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1answer
34 views

Is this a right way to use paired t-test

Problem Description I want to enhance a photo and I have 3 software to do that, out of which 2 are my own. I show users 2 photos and ask them to choose a better one. Now, I compare software 1 vs. 2, ...
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0answers
29 views

Logistic regression for paired comparisons

I am not a statistician; I'm an engineer, so much of this is a foreign language to me, though it seems like it wouldn't be that hard to understand if explained in a different way. I am trying to ...
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1answer
21 views

FWER correction for paired t-test

I have a continuous variable, and a small sample of 8 observations at 4 different time points (before some intervention, and at 3 follow-up time points). My sample, being a preliminary experiment, ...
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0answers
32 views

Am I using Paired Statistical Test Correctly?

I am comparing a feature between correct & incorrect trials. There are N=1194 paired samples $\{x_i,y_i| i=1,2,...N\}$, where x is for correct trials and y is incorrect trials. I am using a ...
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0answers
8 views

Comparing Learning Rates using Unit Curve in R

I have data for an experiment where 2 groups (Role) were tested over 3 consecutive trials for a task and time to complete task was recorded in sec. I wanted to compare the learning curves of the two ...
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1answer
15 views

Correction of mutliple paired samples t-test

In one group of subjects I have four parameters (for e.g. A, B, C, D) measured in two conditions. I want to know whether these 4 parameters differ between the conditions by doing paired samples ...
1
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1answer
22 views

Permutation on multiple Pairwise Comparison with least square means in R 3.1.2

I'm working on a study where I employed an analysis of covariance (Ancova) with unbalanced factors. I used permutation tests to obtain p-values for my estimates since my observation does not come from ...
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0answers
13 views

t-test for control and test group pre and post where pre and post subjects differ

I have been asked to help in analysing an educational intervention that has been completed, with a control and test group, pre and post tests to evaluate the effect of an intervention. It seems the ...
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0answers
29 views

Paired test using GLM with Gamma distribution

I know, that a paired T-test can be formulated in the framework of a linear model for gaussian distributions. I have two vectors of paired mesurements (rates under certain conditions) that follow a ...
2
votes
1answer
27 views

Paired difference test for nonhomogenous variances

Concrete scenario: A random sample of adults in Idaho rate each of 'kombucha', 'apple juice' and 'grape juice' on a scale from 0 to 1. Does the population of Idaho assign significantly different mean ...
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0answers
24 views

Significant difference within line set and between two sets of lines

For my research a person has walked on a treadmill which contains two pressure plates: One below the left foot, one below the right. I would like to compare the force in the z (downwards) direction ...
0
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1answer
19 views

Pretest-Posttest comparison

I am having a hard time doing this on Stata. I have a group of 32 students. All perform a pretest and are scored. Next, half of them are randomized to receiving an intervention and the other half ...
4
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1answer
48 views

When does an unpaired test result in higher p-value than a paired test?

I determined some parameter in a group of subjects under two conditions, such that each subject was tested in both conditions. I want to know if the condition has an effect on the parameter. My design ...
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0answers
17 views

When compare a variable in different times, one has normal distribution, another doesn't, which test should I use?

The question is to compare means of sales volume in different periods. So I got sales period 1 and sales period 2. Sample size is 40. The skewness, kurtosis, test of normality and histogram all show ...
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2answers
36 views

paired-sample t-test

I have taken weight measurements before and after a treatment. When I run a paired sample t-test and if there is a significant change, would it be possible to make the claim "95% of the time ...
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0answers
8 views

Appropriate correction for tests for determining best of family

I have a sample of $N$ instances of a problem (assumed to be independent samples of an infinite population of instances). To each of these instances I apply $M$ methods, and record how quickly they ...
2
votes
1answer
40 views

Longitudinal data analysis with a single group

I need you assistance with finding the right model to analyze longitudinal data with a single group. My data comes from the ophthalmic field, i.e. eyes. I have n subjects. For each subject, one eye ...
1
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1answer
21 views

math explanation for using paired-t

Not a math/stats person, but I am interested in finding out why "paired t" would be a preferred test for samples that are not "independent". I googled a bit on this topic, but didn't really find ...
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0answers
51 views

logistic regression with GLMM (and p-values)

It seems that I'm a little bit confused with the different ways to achieve its goals in the statistics’ world (and the R’s universe), so I’m asking your help about issues with which I'm struggling. ...
3
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1answer
77 views

Bootstrapping Hmisc::rcorrp.cens for paired concordance?

As Frank Harrell says here and other places, it's better to compare two predictive models (Cox proportional hazards in this case) wrt discrimination (C-index) using the paired U-statistic ...
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1answer
29 views

How to calculate correlations of matching pairs

I have very basic knowledge of statistics and would appreciate some help identifying an appropriate method to calculate the proportion of outcomes that agree between pairs of data and whether it is ...
0
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0answers
19 views

How to test differences in multiple pairwise distances? With mixed model?

I want to compare two set of variables: X1 = All the pairwise distances between individuals from group A and group ref R X2 = ALL the pairwise distances between individuals from group B and group ...
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0answers
15 views

lsmeans: how to have mean and SD from pairwise comparison? [duplicate]

In my previous question, I asked about effect size, but this question is about mean and SD from pairwise comparison generated by lsmeans. I am doing LMM starting from model comparisons. Then after ...
2
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1answer
54 views

How to compare pre-post outcome when each subject react differently?

I have 11 subjects with pre and post outcome (two repeated measures). I'd like to test the difference between both conditions. The problem is that each subject react very differently. Here's an ...
0
votes
1answer
35 views

How to show whether the average coefficients of determination from one regression technique are better than another across many objects?

I have 50,000 objects on which I have performed two different types of regression. Using cross validation, I obtained the average $R^2$ score from each model on each of the objects. So now I have a ...
0
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1answer
42 views

Is Student's $t$-test the right choice?

I have 2 patient populations taken from the same time period that underwent 2 different surgical laparoscopic procedures. I want to compare the rate of conversion to an open surgical procedure. In my ...
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0answers
23 views

Can I combine two pairwise comparisons?

I am using LMM in lmer. To find the most optimal model, I compare models of three-level with two level using ANOVA function. If it turns out that no significant difference between these two, then I ...
3
votes
1answer
213 views

Non-parametric version of paired t-test (Mann–Whitney U test)

I have data from 100 individuals doing a 2AFC under a control and a manipulated setting. I want to compare the means. I initially used a paired t-test. My supervisor noticed the distributions were not ...
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1answer
37 views

Which design is most appropriate?

I have data from an experiment testing a new treatment. Each subject has 4 data points, 2 of the new treatment and 2 of the control. It is like a paired analysis, but instead having 1 observation of ...
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0answers
40 views

small n: some variables are normally distributed some are not

We performed a biomechanical study, comparing an intact state to 5 different deficiency states on the same knee cadaver specimen. This was conducted on a very small sample size (n=8). My problem is, ...
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1answer
156 views

Bias-variance tradeoff in the paired t-test

Suppose we have $K$ subjects and a treatment with two levels, "Before" and "After". A paired t-test is equivalent to fitting a fixed effects ANOVA: $Y = Subject + Treatment +\epsilon$ It is also ...
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0answers
32 views

Non parametric anova or two non parametric ttest?

I have a statistical question about a project I recently got. We performed a flow cytometry assay on 3 different groups: controls (n=5), patients before treatment (n=5) and paired patients after ...
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1answer
48 views

Which test to use for paired, nonparametric, categorical data?

We asked a group of subjects to tell us their preferences for a given procedure, of which there were 4 choices. We then provided them with educational material and asked them again of their ...
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0answers
28 views

Comparing similarity of two fingerprint or bitvector

I have a question that's two part. 1) The first part is that I have a bit vector or a fingerprint of a digital circuit where the each bit is high if a specific structure or component exists and zero ...
2
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1answer
193 views

Paired $t$-test when pairing is not known and some subjects responded only in one condition

In testing the difference between a 'pre' survey group and 'post' survey group, I have the same sample population surveyed, yet different sample sizes (fewer respondents within the 'post' group). Am I ...
0
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0answers
27 views

Seeking covariates that can negate the effect size of treatment groups in an ANCOVA model

I was going to build an ANCOVA model with two treatment groups (climbed/unclimbed) and a set of 10 potential environmental covariates which may collectively remove the significance of the climbing ...
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0answers
15 views

Testing dispersion of values between condition on a group

I may have a tricky question. I have a within design where every participant is tested in 2 conditions. I want to compare the dispersion of the measure, for the two condition, with the hypotheses that ...
3
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1answer
108 views

Multi-class classification via all pairwise classifications with LDA

I have trained linear discriminant analysis (LDA) classifiers for three classes of the IRIS data and struggling with how to make the classification. Here is the procedure: For the Iris data, I have 3 ...
2
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2answers
189 views

Comparing performances during a race between 2 groups, which test should I use?

Imagine I organized a race between 2 types of ants. Type A and B. At the end of the race, I have the ranking, which looks something like : ...
1
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1answer
135 views

Nested ANOVA in SPSS / Science Education

I am analyzing student performance on a pre/post test designed to assess gains for a week long high school biology curriculum on natural selection. After comparing pre/post performance using a ...
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1answer
38 views

Repeated measures paired test

I have the following data: 2 conditions - experimental & control. 20 participants, each having 3 results for each condition. Like in the following table: ...
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0answers
414 views

How to report the Pairwise comparison in SPSS

I am using a Kruskal Wallis test for my thesis and want to report the results from this test. However, one of the plots from this test is a pairwise comparison test, which I do not understand. Can ...
1
vote
1answer
77 views

Comparing the performance of two teams measuring many variables once

Which statistical tools are best suited for this problem: Team A goes and measures 3 magnitudes in 200 locations (let's imagine the volume of a room, the insulation coefficient and the average ...
1
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1answer
56 views

How to test whether the absolute change of two paired samples different from zero

I have two paired samples. $\text{Group 1}: X_1,X_2, ...,X_n$ $\text{Group 2}: Y_1,\;Y_2,...,\;Y_n$. $(X_1, Y_1)$, $(X_2, Y_2), ..., (X_n, Y_n)$ are paired respectively. The null hypothesis ...
1
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1answer
95 views

Paired test for comparing boolean data

I have $n$ individuals, and for each individual, I have two measurements using two devices (device X and device Y). I know the ground truth for the correct measurement, and I can classify each ...