The tag has no wiki summary.

learn more… | top users | synonyms

0
votes
0answers
10 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 ...
1
vote
2answers
20 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 ...
1
vote
0answers
6 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
34 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
vote
1answer
18 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 ...
0
votes
0answers
14 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
votes
1answer
53 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 ...
0
votes
0answers
13 views

how to offer recommendation? comparison of satisfaction between two groups?

My research is "level of satisfaction in relation to customer service: comparative study between 2 fast foods my questionnaire consists of 19 questions. I'm using SERVERF, the 5 dimensions. 8 ...
1
vote
1answer
22 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
votes
0answers
15 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 ...
0
votes
0answers
14 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
votes
1answer
47 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
33 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
votes
1answer
37 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 ...
0
votes
0answers
18 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
107 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 ...
1
vote
1answer
36 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 ...
1
vote
0answers
34 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, ...
1
vote
1answer
154 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 ...
1
vote
0answers
25 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 ...
1
vote
1answer
38 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 ...
0
votes
0answers
27 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 ...
1
vote
1answer
105 views

Paired $t$ test - Different Sample size

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
votes
0answers
21 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 ...
0
votes
0answers
10 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
votes
1answer
84 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
votes
2answers
186 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
vote
1answer
58 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 ...
1
vote
1answer
36 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: ...
0
votes
0answers
309 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
72 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
vote
1answer
49 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
vote
1answer
73 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 ...
0
votes
0answers
53 views

Hypothesis test for comparing two F-measures

I have a classifier that classifies each sample point as positive or negative. Suppose I am evaluating it on a limited data set where I have ground truth and then computing the F-measure ...
1
vote
0answers
55 views

Comparing two estimators for accuracy using empirical bootstrap

I am trying to figure out the proper way to compare the quality of two estimators of a parameter based on data. The basic approach I've taken is to compute the MSE of the empirical bootstrap ...
3
votes
0answers
76 views

Interpret the pairwise comparison plot from SPSS

For my user study, I am trying to find out to what extent people prefer to move by foot. They had the option to rank their preference for 'walking', 'jogging' and 'running' for a several amount of ...
1
vote
2answers
61 views

How to compare short (9 points) time-series

I need to compare couples of time series to asses whether they are really different (eg. don't overlap) between themselves and from 0 (don't overlap zero). The easy way is to simply perform paired ...
0
votes
1answer
23 views

opinion poll, t test or paired test or others

Which test should I use to test the difference of monthly opinion poll? If I want to know whether the poll result of April is significantly different from March, should I use independent t test or ...
2
votes
1answer
59 views

Statistical paired test for relative change

Do you have any suggestions, which test I should use in order check if the relative change is statistically different than 0. I am sure that I should check the relative (fold) changes. Specifically, ...
1
vote
1answer
30 views

Testing for paired subjects AND two timepoints

How should I best analyze data that have "2x pairing"? E.g., N set of twins, each twin randomly assigned to active drug or placebo, then measure indicator X at timepoints A (before administration) and ...
0
votes
1answer
29 views

Paired difference test

I am predicting missing values by using two different methods (e.g., data imputation methods). Following I am interested to test if the predicted values, obtained by means of two different methods, ...
0
votes
0answers
13 views

R Prefmod for paired comparisons

I'm trying to use the prefmod package to analyzed paired comparisons, but unfortunately the documentation is a bit poor and the author is no longer with us. I have a survey with 32 questions, split ...
0
votes
1answer
33 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
votes
1answer
32 views

Lsmeans: Is this what I did?

after doing the linear mixed model with lme4, I have used lsmeans for pairwise comparison with this command: lsmeans(lmer52, pairwise~color, adjust="tukey") I am ...
1
vote
1answer
88 views

Paired or unpaired Wilcoxon test?

I counted the number of geese on an intertidal mudflat on 100+ days over the winter. I made two counts on each of these days: one at low tide and one at high tide. I want to know if the number of ...
1
vote
1answer
19 views

Test to compare an effect on a variable on a daily basis

I would like to know the effect of an external factor on the number of visits on a website during a period of 4 weeks (only search visits from Google). For this, I measured the number of visits every ...
1
vote
1answer
158 views

Are pairwise Wilcoxon tests a valid non-parametric alternative to Tukey's HSD test?

I am trying to identify significant differences between groups from normal and non-normal distributions. When the distribution is normal the workflow is pretty straightforward: ANOVA and after that a ...
1
vote
1answer
1k views

Difference between the Wilcoxon Rank Sum Test and the Wilcoxon Signed Rank Test using paired observations

I was wondering what the theoretical difference is between the Wilcoxon Rank-Sum Test and the Wilcoxon Signed-Rank Test using paired observations. I know that the Wilcoxon Rank-Sum Test allows for ...
1
vote
0answers
37 views

What statistical tests can be used on a distribution of distributions?

I have two experimental conditions, each with 20 reps (40 experiments total). In all 40 experiments a non-fixed number of sounds were recorded, and I've measured each of their durations. I would now ...
5
votes
1answer
80 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. ...