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

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Is there a non-boostrap way to estimate confidence intervals for Kernel regression predictions?

Simple problem of estimating: $$ y = f(x) + \epsilon $$ Where I use your standard Nadaraya-Watson Regression to guess $f(x)$. This is relatively fast and works well even in an online setting. Now I ...
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8 views

Kendall W for continuous data

Simple question: can I use the Kendall W test for continuous data? Cuz I used it for a bunch of continuous variables and almost all coefficients are very close to 1, with p-values very very very small ...
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1answer
17 views

Which nonparametric test should I use

I am currently doing an experiment to test whether there is a significant difference between test results of a control group of steel bars of good shape and another group of corroded steel bars. I do ...
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1answer
27 views

what test to use for comparing count data across multiple groups

I have five groups of students and 40 in each. And we counted the number of references spelling mistakes in their homework. We would like to compare to see if there exists any groups differences in ...
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27 views

Testing for Stochastic Dominance - Mann Whitney with Unequal Variance

I've been looking for methods like Mann Whitney, but without homogeneity of variance. So far, I found that I suppose to test for stochastic dominance instead - i.e. modifying the null hypothesis. ...
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32 views

Choosing evaluation measure for non-parametric clustering

I have to cluster some data using non-parametric clustering technique which is given in this paper. After all the cluster evaluation measure used in this paper is Normalized Mutual Information as they ...
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2answers
31 views

Comparing huge data sets that are non-normal and different lengths in R

I'm comparing two data sets. Each set is extremely large, about 25,000 quantitative pieces of data in length. I want to find if these sets are significantly different, but the problem is that they are ...
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2answers
40 views

Density estimation for large dataset

I have a unidimensional data set with more than 1000000 observations. Assuming that those observations are independent realizations of the same random variable I need to estimate the underling ...
2
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1answer
49 views

Equivalent to Spearman correlation for non-monotonic data

I have several datasets of independent variables that have a monotonic (but non-linear) relationship. If I want to assess if they're correlated, the test of choice is Spearman's (rho) or Kendall's (...
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6 views

what test should i use to find the difference of variable based on service tenure?

i have 3 variable which is understanding, motivation and attitude (Likertscale). i want to see if there is difference of service tenure towards these three variable... what test should i use? my data ...
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1answer
23 views

Is Cronbach's alpha a parametric or non-parametric test?

Is Cronbach's alpha a parametric or non-parametric test? I need to know more specific details about it.
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2answers
28 views

Mann Whitney U test with normal distribution approximation: null hypothesis rejected?

I'm new with U test and I have some doubts about the rejection of the null hypothesis with the U test with normal distribution approximation. In my example I used this data for a 1 tailed test: $$ ...
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11 views

Likert-type mediation on non-normal/non-linear data

I have collected data from a questionnaire with multiple questions, all answer possibilities being on a 5-point Likert scale. After initial analysis, my data does not have a normal distribution nor ...
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18 views

parametric or non-parametric in comparison of a dependent variable within several groups

I am comparing maths and chemistry scores of students in several schools. I am not comparing the schools with each other. I am just trying to say that students do better in maths than in chemistry in ...
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2answers
68 views

What are the differences between parametric and non-parametric statistical tests?

I have seen that there are parametric and non-parametric statistical tests. What are the differences between them?
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1answer
34 views

Why results from R's wilcox_test and Matlab's ranksum are not consistent?

I found when using two sample ranksum test, Matlab's ranksum gives different p value from R's wilcox_test (seems to be related to unequal sample size), I'm not capable of delving into their ...
3
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1answer
46 views

Prove the relationship between Walsh averages and Wilcoxon signed rank test

In my lecture notes it is stated that sum of all positive signed ranks (defined in Wilcoxon signed rank test) = the number of Walsh averages that are greater than median How can I prove this ...
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1answer
60 views

If the Epanechnikov kernel is theoretically optimal when doing Kernel Density Estimation, why isn't it more commonly used?

I have read (for example, here) that the Epanechnikov kernel is optimal, at least in a theoretical sense, when doing kernel density estimation. If this is true, then why does the Gaussian show up so ...
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14 views

chisquare outlier test assumptions

what are the assumptions of the chisquare outlier test? ( in R: chisq.out.test()) Is it only applicable if the data follow a certain Distribution? What is the idea of ist Definition of outliers? ...
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1answer
23 views

Rookie question about non parametric and parametric tests

I am a very rookie statistical test user and I want to better understand how to choose between a non parametric and parametric test based on my data. I read several statistical tests tutorials but I ...
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14 views

Bootstrap comparison of group means instead of ANOVA/tukeyHSD

I have several groups (~30, >100 data points per group) and would like to see if there are differences between the group means and where. Both ANOVA and Kruskal-Wallace say yes and I'd like to see the ...
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0answers
13 views

Permutation test for repeated measures (in time)

I have the measurements of a quantity, observed every day for 60 days Usually, this quantity is really near to 0, apart from 3 days where it is (significantly?) greater than 0 I thought it would be ...
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0answers
9 views

How to assess the significant level of a sample difference per number of element

I have 3 samples of 28 paired elements which have been tested for normality and they are not normal due to biomodal distributions. I carried out a Friedman test and is not significant. However I know ...
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27 views

When to use Median test and Mann-Whitney test?

I know that both uses to find whether the two sample medians are equal or not. But I want to know when should I use them? Under which conditions these two tests can be applied separately?
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27 views

Dunnett T3 test interpretation

i have result from a Dunnett T3 test using package DTK in R. The result do not give me any p-value but only "Diff", "lower CI" and "upper CI". i can understand the difference between groups as the ...
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5answers
175 views

How to test an interaction effect with a non-parametric test (e.g. a permutation test)?

I have two categorical / nominal variables. Each of them can take only two distinct values (so, I have 4 combinations in total). Each combination of values comes with a set of numerical values. So, I ...
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1answer
19 views

Comparing capture rates in 2 groups: which test?

I am comparing rate of capture (animal captures per hour) between two years. I'm interested in determining whether there is a difference between rate of capture between the two years. A survey night ...
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2answers
361 views

The correct way to display non-normal data?

In my university we learned a lot about normal data, but handling non-normal data wasn't really covered. For some benchmarking of an application I have data has a very high frequency around one value ...
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18 views

Maximizing a non-parametric Probability Density

Assume we have a set of samples and estimate the underlying distribution with a non-parametric density estimator like the Kernel Density Estimator. Lets assume with a gaussian kernel. In my case it ...
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0answers
13 views

Non-parametric paired data: several Wilcoxon signed-rank tests? Other?

Scenario: I've taken blood samples from a group of patients (n = 15) and measured the expression of one marker on three cell populations within each sample (transitional B, naive B, memory B). I'm ...
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49 views

p-value interpretation of Jonckheere Terpstra:one-sided or two-sided

I am using the Jonckheere-Terpstra test in order to validate the pooled t-test results. Basically, I like the JT test because of its non-parametric nature. Basically, I am now trying to understand ...
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0answers
10 views

Non-parametric analogue of a one-way MANOVA

What is the best test to perform a non-parametric multivariate analysis of variance? I have 4 levels of 1 factor, $n=60$ statistical units and 30 dependent variables.
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7 views

Is there a more improved fitting regression than some local regression methods?

I think that some methods in the local polynomial regression ended issues in terms of curve fitting. That is, these methods almost perfectly seem to fit the data given. Whenever I fit the curve using ...
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1answer
29 views

Betadisper and adonis in R: Am I interpreting my output correctly?

I am currently analyzing next generation sequencing bacterial data and trying to figure out whether bacterial communities differ between regions (seems to exhibit this in nMDS). When running adonis (...
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25 views

Non parametric multivariate analysis

I need some help with my statistical analysis. I have two different pharmacokinetic parameters. They result from two different models applied on the same data. These data are baseline and follow up ...
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2answers
40 views

Most appropriate analysis for non-normal, right-censored response variable?

I conducted an experiment with human subjects in which the independent variable has 3 treatment levels and the dependent variable is the duration of time that passes before the subject engages in a ...
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1answer
43 views

Why run a post hoc wilcoxon signed rank test after Friedman test, why not just skip to Wilcoxon sign test instead?

I understand that one is required to run post hoc tests after the Friedman test. For example, while the Friedman test may find a statistically significant change amongst 3 treatments, one may follow ...
0
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1answer
47 views

Survival analysis with multiple factors

I want to do survival analysis in a situation where I expect the survival time depends on two factors: Environment. Each person is in one of three environments, $E_1,E_2,E_3$. I expect that the ...
5
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1answer
44 views

Are parametric tests on rank transformed data equivalent to non-parametric test on raw data?

Many non-parametric tests are identical to their parametric equivalent on ranked data. At least, that's what I learned from this blog post on Friedman's test and skimming this 1981 article.. This ...
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16 views

Non Parametric test for ranked data

I am working on a project on multi criteria decision modelling. The technique applied (Analytical Hierarchy Process) provides me with data in the form of normalised weights (sum=1) to a set of ...
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0answers
11 views

Is there any test, like Mann Whitney U test or Kruskal Wallis test, that allows me to include a categorical covariate (like an ANCOVA)?

Here is my question: I want to know if there is a test that allow me to do an nonparametric ANCOVA. Let me explain: I am looking for a Mann-Whitney-U and a Kruskal-Wallis, but I want to include a ...
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10 views

How are the values of knots in MARS calculated?

I'm wondering how the MARS algorithm decides on the specific values for the knots which are included in the hinge functions. Thank you very much.
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12 views

Nonparametric test for discovering a unimodal distribution?

I am doing a literature review. I want to count how many times a given HCI concept has been found to have some effect (strong, medium, weak or none, with negative effects that's an ordinal scale with ...
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0answers
25 views

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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31 views

How do I check data for normality, then what next…?

I am currently undertaking a hypothesis test for some financial returns data. I'm getting slightly confused on parametric versus non-parametric testing. I am testing a market portfolio of 305 stocks ...
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175 views

Testing difference between two portions of a time series with Chebyshev Theorem

I have a time series which presents two different patterns during time. These patterns are related to two different events that happen during the experiment. I can manually select the temporal ...
0
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1answer
29 views

Kernel Regression with Multiple Predictors

I know Kernel regression is a type of local regression, i.e., we consider nearby points/observations to predict the value at a particular point. In other words, we see which of the already existing ...
0
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1answer
30 views

Version of Mann-Whitney U test, for right-censored data

Is there an equivalent of the Mann-Whitney U test, but for right-censored data? I have right-censored numerical data from two different groups. The mean for one group is higher than the other. I'd ...
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31 views

Dirichlet process mixture MCMC

I'm reading Markov Chain Sampling Methods for Dirichlet Process Mixture Models by Radford M. Neal. Equation (3.6) states that If $c=c_{j}$ for some $j\neq i $: $P\left(c_{i}=c\;|\;c_{-i}, y_{i}, \...
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30 views

Four standard deviation rules in relation to normality testing

Within our department we were given a set of guidelines for how we might decide whether to proceed with parametric or non-parametric testing (for continuous data). These were drawn up in consultation ...