# Tagged Questions

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By the definition I'll have (1) $S(x)=\begin{cases} S_0 = a_0x^3 + b_0x^2 + c_0x + d_0, & \text{if }t_0\le x\le t_1\\ .....\\ S_{k} = a_kx^3 + b_kx^2 + c_kx + d_k, & \text{if ... 0answers 15 views ### How to analyse individual consistency from three non-normally distributed variables? I would like to know if individuals were consistent across three different days. I measured the latency of individuals for a maximum of ten minutes. Many individuals had a latency of 0 and some ... 0answers 19 views ### Kruskal-Wallis test for factorial design [duplicate] Is it possible to use the Kruskal-Wallis test for two factors and their interaction (i.e., two way ANOVA: Y~a*b)? And which post-hoc test is possible to use after ... 0answers 15 views ### What is the test used in R in sm.regression to compare reference model with kernel regression? I am doing bivariate kernel regression using the sm.regression function: http://cran.r-project.org/web/packages/sm/sm.pdf There is an option to compare the nonparametric estimate with linear model. ... 0answers 50 views ### Is there any model that includes random effects with non-parametric data distribution? I have a non-parametric (by which I mean non-normal) data distribution. I tried several transformations, but none were helpful. Now, I want to find a model where I can include random effects with the ... 1answer 261 views ### How to convert from Mann-Whitney U to Z (or other effect size)? I'm looking at multiple studies. I do not have the original data. One study I'm looking at provides means, standard deviations, and Mann-Whitney$U$values (with$p$). (How) can I convert from ... 0answers 27 views ### Bandwidth selection in multivariate semi parametric estimation in R (np package) I am estimating a semi-parametric and a full non parametric model, by using the np package in R. I have more than 400 observations for T big years, moreover several ... 1answer 93 views ### Entropy estimation for a symbol sequence I am looking for an R-implementation of the Lempel-Ziv data compression algorithm, to estimate the source entropy of a time-series consisting of a sequence of symbols. Rather than simply measuring ... 1answer 161 views ### Hypothesis testing - Wilcoxon test, bootstrapping, or something else? A colleague has developed a treatment for to "prevent falls" in cognitively impaired, psychiatric patients. Since this would be very useful treatment in this population, we especially do not want to ... 1answer 121 views ### Friedman test vs Wilcoxon test for binary IV I'm trying to assess performance of a supervised machine learning classification algorithm. The observations fall into nominal classes (2 for the time being, however I'd like to generalize this to ... 2answers 47 views ### Influence of two factors on non-normal outcome. Which test? I measured two variables (outcomes)$Y_a$and$Y_b$for several subjects.$Y_a$and$Y_b$are continuous variables defined on$[0,100]$and have a bimodal distribution. I tried using a transformation ... 1answer 3k views ### What is the non-parametric equivalent of a two-way ANOVA that can include interactions? Hi I am trying to find the non-parametric equivalent of a two-way ANOVA (3x4 design) which is capable of including interactions. From my reading in Zar 1984 "Biostatistical analysis" this is possible ... 1answer 108 views ### State of the art: Non parametric density estimation with a boundary and data clumped near zero I have some data which I wish to estimate the marginal distribution of. I have no real idea what parametric distribution would be suitable, so was planning on fitting a non-parametric (probably ... 0answers 50 views ### Testing significances in Likert type items I have a questionnaire of 18 questions with Likert-type answers, going from 1-5. One of them was administered to parents, one to their children. I need to test 2 thing: a) within each group, are the ... 0answers 85 views ### Exact p-value for any nonparametric test After having found the R-package coin, I have a question. For example, to get an exact p-value, I could use the function ... 0answers 29 views ### Multidimensional nonparametric test of variance Let's say I have two or more sample populations of$n$-dimensional continuous-valued vectors. Is there a nonparametric way to test whether or not these samples have the same variance? e.g. like a ... 0answers 150 views ### Test if multidimensional distributions are the same Lets say I have two or more sample populations of n-dimensional continuous-valued vectors. Is there a nonparametric way to test if these samples are from the same distribution? If so, is there a ... 0answers 640 views ### Power analysis for Kruskal-Wallis or Mann-Whitney U test using R? Is it possible to perform a power analysis for the Kruskal-Wallis and Mann-Whitney U test? If yes, are there any R packages/functions that perform it? 0answers 34 views ### Non-random distribution of SNPs (single-nucleotide polymorphisms) I have a bunch of groups of DNA sequences in which I have observed changes in different regions (block D and H) vs. the rest of the molecule. The data is available as a table like the one below. The ... 2answers 108 views ### Nonparametric test To get the power of the t-test I use this R code: pwr.t.test(n=25,d=0.35,sig.level=0.05,type="one.sample",alternative="greater") and for the test of the Pearson ... 0answers 83 views ### Derivatives of multivariate local polynomial regression? Is there an R package that finds the derivative of multivariate local polynomial regression? In univariate setting, KernSmooth does this. But I don't know there is multivariate counterpart. 1answer 345 views ### Best way to test runs I have the following sample: ... 2answers 145 views ### Robust ANCOVA literature I am looking for some source of information, some articles about Robust ANCOVA. Can you suggest me something? And do you know any source that directly gives information about how to perform various ... 1answer 2k views ### How do I interpret the Mann-Whitney U when using R's formula interface Say we have the following data: ... 0answers 183 views ### Help with Theil-Sen regression function (written in R) I have written a function (in R-language) to perform a Theil-Sen regression with large sample approximation (please see below). It seems to work well for the one-sided case as illustrated in ... 0answers 205 views ### Repeated Measures in R, SAS or SPSS: Whale Body Temperature Data I have a question regarding a repeated measures experiment. I have 5 whales (randomly selected) that I recorded body temperature on. Data was collected via satellite, programmed to transmit records at ... 3answers 342 views ### How to test my data against an specific normal distribution? I need to test my data to see if it follows a normal distribution with specific mean and std like N~(mu, std) I know that this can be done by Kolmogorov-Smirnov test which has a function in both ... 0answers 484 views ### How to interpret results from non-parametric ANCOVA? I 'm new to the CV and not very good at statistic:) I would much appreciate some help on a non parametric ANCOVA in R sm package. I do a pre post analysis on a set of pre/post variables of two groups ... 1answer 145 views ### Randomization Tests The following data are mandible lengths (mm) of 10 male and 10 female golden jackals Canis aureus in the collection at the British Natural History Museum. The two samples are independent. ... 0answers 293 views ### Non-Parametric Regression with Ordinal Independent Variables I'm trying to find a model to predict a test score (0 to 100) from many independent ordinal variables (all are on a 1 to 10 scale). Since there are SO many ordinal variables, using binary dummy ... 0answers 39 views ### How do I extract difficulty and discrimination from a non-parametric IRT model I've been using the KernSmoothIRT module in R to do non-parametric analysis of some items. I'm trying to find a way to quantify the difficulty and discrimination ... 0answers 231 views ### Intuition behind tensor product interactions in GAMs (MGCV package in R) Generalized additive models are those where $$y = \alpha + f_1(x_1) + f_2(x_2) + e_i$$ for example. the functions are smooth, and to be estimated. Usually by penalized splines. MGCV is a package ... 0answers 112 views ### Which 'delta' to use from those returned by 'orddom' package in R with argument 'paired = TRUE'? I have used the orddom package in R with the argument paired = TRUE to calculate the Cliff’s delta for paired groups, and a ... 2answers 1k views ### Permutation test in R I have the following data for 10 subjects based on before and after measurements: ... 1answer 789 views ### Comparison between bootstrap percentiles confidence interval and BCa confidence interval? I have generated a nonparametric percentiles bootstrap confidence interval ($32.27143, 51.08571$), and a BCA confidence interval ($33.26, 53.49$) with an initial sample size of$n=7$. Evidently, the ... 0answers 724 views ### In R, why are results different for 1-tailed wilcoxsign_test, wilcox_test, and wilcox.exact with paired data? I am trying to determine why I am getting different results with these different Wilcoxson test implementations in R version 2.15.2. I have paired data with some ties. I have read the response for ... 1answer 2k views ### Nonparametric equivalent of ANCOVA for continuous dependent variables I have an independent categorical variable ($X$with two categories,$x_{1}$and$x_{2}$) and two continuous dependent variables ($y$and$z$). Using a Mann Whitney test, I know that$y$is ... 1answer 1k views ### Two-sample one-sided Kolmogorov-Smirnov test vs one-sided Wilcoxon-Mann-Whitney test I've read in the library manual for test ks.test that The possible values "two.sided", "less" and "greater" of alternative specify the null hypothesis that the ... 0answers 59 views ### Linearity and ordinal variables in nonparametric setting I am using the np package in R with the npregiv command. The program is in beta, and I cannot call ordered(var) on one of my instruments (a bug in the program I am ... 1answer 2k views ### Is there an alternative to the Kolmogorov-Smirnov test for tied data with correction? I've got a bunch of data from two samples (control and treated), each containing several thousand values which are to undergo significance testing in R. Theoretically, the values should be continuous, ... 1answer 2k views ### Is there an optimal bandwidth for a kernel density estimator of derivatives? I need to estimate the density function based on a set of observations using the kernel density estimator. Based on the same set of observations, I also need to estimate the first and second ... 0answers 971 views ### Non-parametric alternative to linear regressions in R I want to run series of simple lm in R, with a continuous/categorical outcome and binary group membership (patients - controls) and categorical predictors. However the categorical predictor is ... 1answer 391 views ### Post-hoc analysis on Friedman's test I am using a Friedman's test with post-hoc analysis. I am using the function friedman.test.with.post.hoc available for R software. Lets say we have 6 wines and we ... 2answers 707 views ### Wilcoxon-Mann-Whitney critical values in R I have noticed that when I try to find the critical values for the Mann-Whitney U using R, the values are always 1+critical value. For example, for$\alpha=.05, n = 10, m = 5$, the (two-tailed) ... 0answers 432 views ### Kaplan-Meier multiple group comparisons Lets say I have the following data frame ... 2answers 218 views ### Assuming my three data series are each$\chi^2(1)\$ distributed, are they different from eachother?

I systematically chose rare words from three groups of texts (#1, #2 and #3) (the rare words within each group are different, but some rare words may appear in more than one group). Then, for each ...
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### How to run two-way ANOVA on data with neither normality nor equality of variance in R?

I am working on my master thesis at the moment and planned on running the statistics with SigmaPlot. However, after spending some time with my data I came to the conclusion that SigmaPlot might not be ...
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### Non parametric cointegration test in R

I am not very comfortable with the (parametric) assumptions made in cointegration analysis. I have recently found that there is a way to carry out nonparametric conintegration analysis (a google ...