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

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21 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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6 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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17 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
33 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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17 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 ...
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1answer
17 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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19 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 ...
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24 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 ...
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2answers
38 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?
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2answers
36 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 ...
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10 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 ...
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1answer
60 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 ...
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1answer
37 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...”. ...
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24 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
18 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
35 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. ...
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2answers
65 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 ...
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2answers
78 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!!!
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0answers
19 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 ...
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0answers
14 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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49 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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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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19 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 ...
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1answer
102 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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11 views

Can I examine the confounding effect of variables on non-normal data using Pearson?

I have used Kendall's tau to examine whether there is a correlation between a number categorical variables, as I have a small sample. However, I also want to test whether some variables might have an ...
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16 views

In practice, how is the penalisation matrix for splines, created by smoothCon (package mgcv), specified?

Evaluating a smooth object with smoothCon provides, besides several other things, the ordinary "untouched" spline bases ...
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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, ...
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18 views

Problems with calculation of numerical identification w.r.t. ANOVA smooth for large scale matrices

Suppose we have two (centered) Spline-matrices $\boldsymbol{B_1}$, $\boldsymbol{B_1}$. Then $\boldsymbol{X_1} = [\boldsymbol{B_1},\boldsymbol{B_2}]$ contrains lower order smooths and ...
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21 views

Multiple comparisons on nested subsets of data for a non-parametric test

My problem: I'm using data sets where some are nested in a non-parametric test that expects independent data sets. How can I correct for that in a way that is reasonable? Or even better: What would ...
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1answer
22 views

Effect of sample decimal points on power in rank-based tests

I perform different rank-based non-parametric tests (Friedman and Nemenyi) post-hoc and noticed that the decimal places of the samples have a strong effect on their power. Please consider the ...
2
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20 views

Stores and ordered rank of products

I have data about popularity of some products in some stores. For each of the stores I have only a ordered rank of best-selling products in them. I need help how to find information about which ...
4
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2answers
178 views

Why am I getting inconsistent results from Wilcoxon signed rank test and Kruskal-Wallis test?

I am doing a study on 3 drugs, comparing response pre-post treatment. My objective is to know if these drugs are effective and which one is better. I used non parametric tests since the results ...
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0answers
21 views

How to calculate confidence interval for difference (or ratio) of two different time series?

I have two time series which are sampled at the exact same times. I would like to calculate a confidence interval either for the ratio between the two or the difference between the two. The values ...
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1answer
26 views

What R packages are available for nonparametric regression of two predictors?

I would like to fit a nonparametric regression model with two predictors. What R packages are available? I found 'loess' function in 'stats' package and 'gam' function in 'gam' package. Is there ...
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3answers
210 views

Should I use t-test on highly skewed and discrete data?

I have samples from a highly skewed dataset about users' participation (e.g.: number of posts), that have different sizes (but not less than 200) and I want to compare their mean. For that, I'm using ...
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16 views

Comparing transaction counts between samples

I have a treatment group and two control groups for customers and the count of their transactions: ...
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1answer
37 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
14 views

Fast evaluation of univariate KDE?

I have a KDE obtained with a large sample ($n=10000$). Given that this is defined as the mean of the kernel evaluated at $n$ points, the evaluation of this kernel slows down my code (I need to ...
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19 views

Non-normal data (ceiling effect) and intraclass correlation

I am wondering if there is any way of doing an intraclass correlation, two-way, mixed, with non-normal data (in this case a ceiling effect)? Alternatively, what the interpretation (if any) would be? ...
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1answer
13 views

Is the Friedman Test Suitable For an Analysis of Pre/Post-Intervention Choices From Survey Data?

We sent out a survey to find if educational material about a type of surgery would potentially influence the decision of subjects. Prior to giving them this educational material we asked them ...
7
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1answer
783 views

Should I use t-test on highly skewed data ? Scientific proof, please?

I have samples from a highly skewed (looking like an exponential distribution) dataset about users' participation (e.g.: number of posts), that have different sizes (but not less than 200) and I want ...
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0answers
16 views

How to analyze data with unequal observations per cell?

I've got a very poorly designed study, and I need to find a way to analyze the data I've collected. Here's a description of the design: There are two within-subjects variables, one with four levels ...
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52 views

Repeated measure two-way ANOVA (non-parametric)

Non-parametric ANOVA – a hot topic that is unanswered. There are many questions on this topic online. However, they all seem to end in a debate and no definite answer or clear explanation (that I ...
4
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0answers
63 views

How exactly is the sum (or mean) centering constraint for splines (also w.r.t. gam from mgcv) done?

The data-generating-process is: $y = \text{sin}\Big(x+I(d=0)\Big) + \text{sin}\Big(x+4*I(d=1)\Big) + I(d=0)z^2 + 3I(d=1)z^2 + \mathbb{N}\left(0,1\right)$ Let $x,z$ be a sequence from $-4$ to $4$ of ...
2
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3answers
88 views

How do I compare sample means in this experimental-control group study?

I am hoping to compare the sample mean of an experimental group to the sample mean of three control groups. Here is some context for the study: The experimental group consists of ~60 persons with a ...
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0answers
20 views

Non parametric test for multivariate data

Please suggest a non parametric test that is analogous to the MANOVA. I have 7 nutrient intakes of men and women. How do I test if their intakes are equal?
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1answer
21 views

Sum of Squares Constraint Regularisation

Suppose I have a function $g_0\in L_2(\mathbb{R})$ such that we observe $(X_i,Y_i)$, $i=1,...,n$ such that $$ \begin{align*} Y_i & = g_0(X_i) + V_i \end{align*} $$ We wish to estimate $g_0$, ...
3
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1answer
273 views

Multiple comparisons in a non-parametric test

I am working with a data set that is non-parametric and has 12 treatments. I performed the Kruskal-Wallis test and got a significant $p$-value, and now I would like to conduct a multiple comparisons ...
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2answers
68 views

Which test do i choose to conduct on my Likert scale data?

I have been doing plenty of research into which test I should use on my Likert scale data and i am becoming more confused as there are so many people saying different things. I am currently doing my ...
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1answer
28 views

Approaches for extracting single-year age estimates from age-buckets

I'm trying to estimate a binary function of $Y$~$Bernouli(p_{i})$ where $p_{i}=f(age)$ where f is an unknown continuous function. There are obviously a lot of methods to try to reconstruct f (splines, ...