Procedures that rely on relatively few assumptions about underlying probability distributions.

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1answer
14 views

Dependent samples but unable to pair individual scores

We surveyed a group of students before an in-school year-long project and after, and want to see if the changes in scores are significant. Data doesn't meet assumptions of normality. Can we use the ...
1
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1answer
39 views

Paired samples or independent sample hypothesis test for two time periods

I want to know if employees in an organization are surveyed in 2013 and again in 2014 if the samples from the two time periods are considered related and dependent or independent if they are asked the ...
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0answers
12 views

Goodman Kruskal with ordinal and categorical variables

I have a data set of 100 people grading likelihood of future recall from highest to lowest for a set of memory targets. I am only interested in them making this judgment on unrecalled items, meaning ...
2
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1answer
45 views

Mann-Whitney U test when only summary data (mean, sd, sample size) are available

When raw data is not available, which normally occurs when we obtain our data from different scientific papers, how is it possible to perform a Mann-Whitney analysis to test whether two samples are ...
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0answers
23 views

What is the relationship between degrees of freedom and number of comparisons in Nemenyi's post hoc test?

I have some data consisting of non-normally distributed samples drawn from one of several different groups. A Kruskal-Wallis 1-way ANOVA rejects the null hypothesis that the medians of the groups are ...
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0answers
59 views

Estimating the 95th percentile of nitrate data using non-parametric Weibull method, with associated confidence intervals in R

I am currently involved in a project where I have to estimate the 95th percentile of nitrate data from different sample points, using the non-parametric Weibull method, to see if it breaches the ...
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1answer
39 views

multiple pair wise nonparametric comparisons

is it possible to perform multiple pair wise nonparametric comparisons (generally using a Mann–Whitney test) and adjust the significance level used for the decision criteria using a Bonferroni-type ...
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0answers
14 views

Multiple Comparisons testing and Dunn's Test

I have 8 different groups of individuals, each with a pre- and post-treatment measurement. The data are non-normal, so I used a Jonckheere-Terpstra test to test for an ordered alternative and ...
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0answers
30 views

Rank deficient bootstrap resamples

Despite years of stat courses I'm afraid I may still not completely understand bootstrapping. My question here relates to nonparametric boostrapping of regression models. As i understand it you draw ...
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0answers
28 views

lay stats question

I am comparing two prospective observational cohorts; the "study group" (n=30) has undergone previous intervention that "failed" and has undergone a 2nd intervention. This is being compared with a ...
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0answers
38 views

How to pool the interquartile range for an arbitrary distribution?

Let's say that I want to estimate the temperature in an annulus-like region. I split the annulus into four equal sectors (sectors 1,2,3, and 4) with $n_i$ being the number of measurements in sector ...
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1answer
50 views

Using nonparametric tests with small samples even when data are normaly distrubuted

Is it appropriate to use a nonparametric test with a small sample (e.g., less than 65 people) even when data are normally distributed? For example, using the Spearman correlation? Actually my data is ...
1
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1answer
37 views

nonparametric method to calculate the probability how alike two samples are

I have two samples with each couple of hunderd observations. I want to calculate a probabilty how much they look alike. I'm aware of tests like kolmogorov smirnov but I don't think I need this. I ...
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1answer
35 views

Likely mean of a multinomial distribution with dirichlet prior

I am working to create a Bayesian non-parametric estimate of the mean of a distribution given a distribution of observations. Ultimately I'd like to get to a credibility interval of the likely mean of ...
2
votes
1answer
27 views

What does “CRP is a marginalized version of PYP” mean?

I've been reading this phrase and I don't know what it means "CRP is a marginalized version of PYP". What are the parameters/latent-variables we are marginalizing out to drive CRP from PYP?
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0answers
29 views

How to perform Friedman's test with covariates

I have 500 participants who each completed 30 trials. In each trial they need to choose the correct image out of three (a three-alternative forced-choice task). Of these thirty trials, 10 trials ...
3
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1answer
57 views

Why are there two forms for the Mann-Whitney U test statistic?

I have encountered two forms for calculating the two-sample Mann-Whitney U test statistic, which are: $$U_1 = R_1 - \frac{n_1(n_1 + 1)}{2}$$ and $$U_1 = n_1n_2 + \frac{n_1(n_1+1)}{2} - R_1$$ where ...
1
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1answer
33 views

What is a one-way ANOVA on the ranks of the observations

While reading this link: http://www.statsdirect.com/help/Default.htm#nonparametric_methods/kruskal_wallis.htm, I came across the following: ...
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1answer
24 views

Reporting results of a Quade test

I have been scouring the internet to find out how to report the results of a Quade test (non-parametric equivalent of ANCOVA). Does someone have an example that explains this in plain terms? I'm not ...
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0answers
18 views

Is it okay to use lots of different statistical tests within the same dataset due to not fulfilling parametric assumptions?

I'm trying to reconcile the results of a study, and the fact that we need to do lots of different types of statistical tests to show a few conclusions in a paper. If the data were normally distributed ...
7
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0answers
78 views

Generalized additive models — who does research on them besides Simon Wood?

I use GAMs more and more. When I go to provide references for their various components (smoothing parameter selection, various spline bases, p-values of smooth terms), they are all from one ...
1
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0answers
21 views

Non-parametric effect size

Effect size, as estimated by Cohen's $\delta$, is: $d=\frac{\hat x_1 - \hat x_2}{\hat s_{pooled}}$ Since the numerator is an estimate of difference in location, and the denominator is an ...
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0answers
13 views

Risk in density estimation: grasping the definition

When generalizing estimators to an entire function what is the space in which we perform the integral to obtain the expected value (with respect to this function)? For example, when estimating ...
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2answers
104 views

Any other non-parametric alternative to Kruskal-Wallis?

It looks like Kruskal-Wallis is the standard nonparametric test for more than two groups. The problem is that it does not tell which groups are different, except that whether there exists significant ...
14
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5answers
392 views

A principled method for choosing between t test or non-parametric e.g. Wilcoxon in small samples

Certain hypothesis tests can be approached using Student's t-test, possibly using a Welch correction for unequal variances, or by a non-parametric test such as Wilcoxon paired signed rank test, the ...
2
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1answer
44 views

How to cope with non-normal ANOVA residuals?

My data follow this outline: ...
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0answers
33 views

non-parametric tests with significant difference in sample sizes

I have outcomes from a biological expt., where we have measured DNA lengths that has been affected. For condition1, I have 11 observations (length of DNA) and for condition2 I have approx. 116000. I ...
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0answers
9 views

What options do I have to analyze Non-parametric version of two-factor ANOVA with repetition?

Sorry, my previous question was not very clear I deleted it and am trying again. Question: What options do I have for two-factor non-parametric version of ANOVA with repetition? What is the ...
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0answers
31 views

How to make non-parametric distribution estimation with known, limited number of points of the CDF?

Is there any method to make non-parametric estimation of a cumulative distribution function (CDF) which actual points (not a sample) can be calculated numerically? I have a numerical method which can ...
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2answers
46 views

How to apply Mann-Whitney test Control vs Treatment Group

I have a treatment and a control group: both have pre- and post- values (I tested reading speed). I need to know if there are any significant differences between the groups (or if the treatment group ...
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0answers
18 views

Minimum sample size in nonparametric data

My population has more or less 80,000 individuals and I would like to take a small sample with a high probability it is really close to the whole population. The problem is that my data is ...
2
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1answer
22 views

How to choose a kernel for KDE

There are a lot of kernels available for a univariate KDE. R uses normal by default, but the efficacy discussion seems to support the use of Epanechnikov. What should influence kernel choice for ...
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0answers
42 views

Two-way between groups ANOVA for non-normal data

I'm doing a study on visual selective attention (VSA) and how this is influenced by gender and video gaming. So my dependent variable is VSA (continuous) and my two independent variables are gender ...
2
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0answers
34 views

Nonparametric tolerance intervals for discrete variables

Suppose you have a bunch of people rate how much they liked a movie on a discrete scale from 1 to 10, and you would like an interval [l, u] such that with (at least) 95% confidence, (at least) 90% of ...
2
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2answers
45 views

Parametric test or nonparametric?

I have 2 groups of sample sizes 10 and 11 respectively. Can I apply a parametric or nonparametric test to find a significant difference in means between the groups?
2
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2answers
39 views

Multiple models compared over same data

My question boils down to if I really have to use a multiple comparison adjustment or not, and if so, how I can do this to retain as much power as possible. I have multiple models (say 5) that are ...
0
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0answers
13 views

Regression analysis is dependent of non-parametric test result?

If I have two variables (i.e. number of pills and skin sensitivity) and I performed a Kruskal-Wallis or ANOVA which gave me no significant differences in any group. Does it make sense to perform a ...
1
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1answer
96 views

How to compare count of two groups?

I have a two groups of data - 1/ All data and 2/ Selected_season, which is only some subgroup of all data. I want to find out: a/ if proportion of BM, HB, etc. groups is the same in All data and ...
0
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1answer
44 views

Regression discontinuity

I am analyzing some Stata code for a regression discontinuity analysis. The results of this analysis are presented in table 5 of the Online appendix to “The Effects of a Universal Child Benefit...”. ...
2
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0answers
49 views

ANOVA on ranks?

Once in a statistics class I've seen the suggestion that one non-parametric approach for ANOVA would be to perform the ANOVA analysis on the ranks of the original data (basically as an alternative to ...
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0answers
28 views

non parametric index model (Klein Spady) for more than two choices in R

The np package offers an easy way to fit the Klein Spady estimator for index model on dichotomous responses. How to use the np package to extend these methods to the polychotomous (i.e., more than two ...
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0answers
51 views

Glm with Poisson in R with no p-value?

I've been doing glm and thought I had it cracked but looking at some sites for interpreting results I realised R had displayed my results oddly. ...
3
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2answers
80 views

Book for introductory nonparametric econometrics/statistics

My work implies a lot of econometrics, and I had a good formation about it. Nevertheless, I am regularly faced with some semi or non parametric techniques (for instance I had to use quantile ...
1
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2answers
95 views

Log transformation not making data normal

I have a data set with positive skewness when I log tranform it tends to be negatively skewed. Is there any other transformation that I can use or any statistical method works? Thanks!!!
0
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0answers
22 views

Batched bootstrap for non-parametric confidence intervals

I am conducting multiple experiments on moderately large datasets that run over several weeks. I would like to construct confidence intervals for my estimators which are a mixture of means and ratio ...
0
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0answers
22 views

Friedman/Wilcoxon test. How to enter data for multiple repetitions?

Id like to run a non parametric test such as the Friedman test on a dependent variable of my 8 subjects who have done a task under four different conditions. I only found examples of how to input the ...
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0answers
98 views

Can I normalize Ordinal Data

I have ordinal data on three IVs ranging from 1 to 5 as below: IV1: Not at all Important - Very Important IV2: Not at all Satisfied - Very Satisfied IV3: Performs much Worse - Performs much better ...
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0answers
18 views

How to judge a nonparametric estimator empirically?

Suppose we have an estimator $\hat{f}(Y_1, \cdots, Y_n)(t)$ for the fixed design nonparametric regression model: $$ Y_i = f(\frac{i}{n}) + \epsilon_i, \; f \in L^p[0,1]. $$ The estimator at hand ...
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0answers
26 views

Appropriate analysis for this experimental design - non-normal data

I've run an experiment with 8 subjects, which had to perform [a series of 4] navigational tasks under 4 different vision conditions each. The experiment was repeated weekly, 16 times with the same ...
3
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1answer
217 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 ...