Questions tagged [nonparametric]

Use this tag to ask about the nature of nonparametric or parametric methods, or the difference between the two. Nonparametric methods generally rely on few assumptions about the underlying distributions, whereas parametric methods make assumptions that allow data to be described by a small number of parameters.

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75 views

How to find the difference between two set of scores of a single participant?

What I am trying to do? I have a data set which consists of only one undergraduate student's all courses scores. Let's assume, he has completed about 70 courses where 40 courses are related to ...
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1answer
198 views

Comparison of medians

I`m currently an Intern and one of my tasks is to asses whether certain variables were optimal for a control system. In total there are four variables which can vary, and to avoid a complicated ...
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26 views

p value is not significant but plot shows clear trend line [closed]

x variable is density, y variable is PMI. The dataset below is just an example. (Data is not normally distributed, sample size 124, Spearmans rho 0.1877085 (PMI~den), Kruskal-Wallis rank sum test p-...
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How to prove a multivariate r.v. does not follow the nonparanormal distribution?

Background You may find the definition of the non-paranormal distribution at the 2nd paragraph in p.2296 of this paper. In short, $(X_1, \ldots, X_p)$ is non-paranormal if there exists a set of ...
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1answer
118 views

Transforming non-normal to normal distribution and back-transform

I would like to transform non-normal distribution to normal distribution, and back-transform to its original state (or at least close to the original state). From this article, I've read that you can ...
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3 views

Testing for interactions using the aligned rank transformation test (non-parametric two-way ANOVA)

I am completing an aligned rank transformation as follows, using the ARTool package: ...
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1answer
1k views

Comparing effect sizes across different data sets with non-normal data

I want to conduct a comparative analysis across a large amount of studies by looking at the effect sizes of their results with another variable. I am not too familiar with effect sizes so I'd ...
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2answers
133 views

Nonparametric Identification from Order Statistics

Suppose a vector of random variables $(X_1,...,X_n,Y_1,...,Y_m)$ is such that $X\sim F(\cdot)$ and $Y\sim G(\cdot)$. So $X$ are distributed independently and identically as $F(\cdot)$ and $Y$ as $G(\...
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1answer
58 views

Alternatives to three-way ANOVA with unbalanced and non-idependent data, non-normal distribution of the residuals and heterocedasticity

I have a response variable ("Value") and three categorical variables for which I want to test the main effects and interactions. ALL DATA COMES FROM ONE INDIVIDUAL for which we have data over time. ...
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1answer
34 views

Estimate correlation in non-normally distributed (e.g. Poisson), unbalanced, repeated measures data

I have a large behavioural data set, and I would like to measure pairwise correlations between several of my outcome variables, and binned categories of outcome variables. However, I have multiple '...
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3answers
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Is there an equivalent to Kruskal Wallis one-way test for a two-way model?

If the model does not satisfy ANOVA assumptions (normality in particular), if one-way, Kruskal-Wallis non-parametric test is recommended. But, what if you have multiple factors?
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208 views

Nonparametric test for comparing learning gains

I have two groups (control and experimental) with 16 subjects each. Their pre-test scores are statistically different from a normal distribution so I opted to do nonparametric tests. I need to compare ...
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5k views

Is Principal Component Analysis a parametric method?

Principal component analysis assumes that the features are distributed by a Gaussian. Does this make Principal Component Analysis a parametric approach? I can't seem to find a concrete answer saying ...
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29 views

Using paired t-test or Sign test to compare two groups of correlated measures on the same subject?

I have conducted a survey where participants are shown 8 different advertisements: 4 of the ads attempt to evoke the feeling of guilt, 4 others attempt to evoke the feeling of shame. After seeing each ...
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How to analyze effect effort has on catch of rare species?

I have df which has year, basin, number of sampling sites per basin for each year and then percentage of rare species (this classification is arbitrary, but it groups certain species as rare based on ...
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How to fit a power curve for a glm with simr

My response variable is counts of turtles at sea surface per aerial survey (possible values: 0,1,2) and I use a Poisson distribution for it (since my data are not overdispersed neither zero inflated). ...
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1answer
27 views

How Parzen window density estimate $f_n$ converges to f

I am trying to understand how Parzen window density estimate converges to actual density function f(x).[Actually i am trying to learn machine learning on my own using available free resources. Please ...
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2answers
164 views

Regression discontinuity - optimal bandwidth choice

I have a very basic question. I would like to implement a nonparametric RD but I have a Poisson outcome variable. I would like to select the proper bandwidth and my question is about which method to ...
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Doubt in kernel based method - unit hypercube(Parzan window estimate)

I recently started studying pattern recognition on my own. Please clarify me the following. https://books.google.co.in/books?id=T0S0BgAAQBAJ&pg=PA53&lpg=PA53&dq=hypercube+of+side+h&...
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41 views

Finding the right hypothesis test

I have two distributions (Generic and Generic Masked) that I want to compare. I want to show that one is distributed closer to 1 than the other, but don't know which hypothesis to test for this. I ...
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1answer
50 views

Significance testing on two groups (distributions) of many binomial distributions

Basically I have two (or more) different success probability generating distributions. In other words, there are two (or more) different (non-normal) distributions, which realize success probabilities ...
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15 views

Correct for Multiple Comparisons or Not?

I am running an analysis of four animals who have received a drug infusion and am monitoring neurotransmitter concentrations over time. I want to see if the concentration has changed from their ...
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1answer
2k views

Fligner-Killeen test of homogeneity of variances interpretation

I have two samples that I want to verify that variances are equals in order to apply Wilcoxon rank sum test that assume that the variance are equals. Here a boxplot As you can see the variance ...
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13 views

How to improve accuracy of estimated cross derivative?

I'm trying to estimate a parameter defined as $\theta=E(X\frac{\frac{\partial^2 g(X,Y)}{\partial x \partial y}}{f(X,Y)})$, where $f(x,y)$ is the unknown joint pdf of $(X,Y)$ and $g(x,y)=E(R|x,y)$ is ...
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1answer
235 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 ...
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1answer
351 views

Reporting the results of Nonparametric regression using kernel weights

I am wondering how I can present the results of nonparametric regression. I performed the nonparametric tests using R, and R package 'np'. The commands used for this are freq <- npreg(Respno ~ ...
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12 views

Is it possible to include covariates with Friedmans test?

I want to test if there is a differece between diets and score1, score2 and score3 on non-normally distributed data. It is a repeated measure design so I think I will use Friedmans test. I wonder if ...
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1answer
602 views

How to do a stratified nonparametric test?

I'm trying to use the "coin" (conditional inference) package to perform a stratified nonparametric test for difference in distribution (for count data). I tried a stratified Mann-Whitney-Wilcoxon ...
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2answers
26 views

Is there a Bayesian Non-Parametric one-way ANOVA?

The rough idea is that I am trying to compare linguistic properties (e.g. readability) between pieces of texts from two authors essentially. For this, I thought using an ANOVA would be appropriate. ...
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34 views

Help with the Mann–Whitney U test

I am new to statistics and really struggling here. I would appreciate any help that I could get. I am supposed to use a non-parametric test (Mann-Whitney U test was suggested) to check the difference ...
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48 views

What is the sample form of the following variance

If $x_1, \ldots, x_n \in \mathbb{R}^p$ i.i.d. a specific distribution. denote: \begin{equation*} \mathbf{X} = \left( \begin{array}{c} x_1^{\top} \\ \cdots \\ x_n^{\top} ...
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1answer
39k 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 ...
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1answer
141 views

Excepted conditional density and conditional expectation

Apparently one can obtain a regression analysis as $$g(x)=\frac{\int yf(y,x)dy}{f(x)}$$ where $$f(x)=\int f(y,x)dy$$ is the marginal density of $X_i$. In effect, I believe, the above expression ...
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17 views

Which stats test (Kruskal-Wallis, Mann-U or Friedman's) for comparing multiple parts of an experiment?

I have data from how long it took male beetles to respond to a female beetle pheromone (and indeed if they did so as over half didn't and none of the controls did). There were two pheromones tested. ...
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67 views

why binomial test is considered “nonparametric”?

why binomial test is considered "nonparametric" ? After all it is used to test against an hypotetical parameter p in a binomial distribution, so IT IS about a parameter ! edit:I don't remember ...
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2answers
10k 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?
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20 views

Kruskal-Wallis Test: Identically Shaped Distributions

I'm currently working with the Kruskall-Wallis test and had a question about what people mean when they speak about 'Identically Shaped Distributions' and how I could identify whether my data fits ...
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1answer
52 views

Is it appropriate to examine the density plot for time series data?

Usually we use time plot to examine the behaviour of time series data cause it reveals the chronological characteristic. Does it make sense that one looks at the data distribution using some non-...
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1answer
343 views

Can Spearman's correlation change between pre and post treatment?

I have a sample of 9 patients. If I evaluate the correlation with the Spearman's test between some variables I measured in time 0 and then I repeat the same test with the same variables in time 1, is ...
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1answer
28 views

Identify relations inbetween categorical and ordinal/continuous variables

I'm evaluating a survey regarding the opinion. Now I check for relations/similarities inbetween the independent variables. My German workbook names the following condition for a Spearman rank ...
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19 views

Question about possible typo in a tutorial about the stick-breaking model of the Dirichlet distribution

I am reading a tutorial on the Dirichlet distribution: http://mayagupta.org/publications/FrigyikKapilaGuptaIntroToDirichlet.pdf and I think there is a typo in Step 2 of the stick-breaking model of ...
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1answer
695 views

What is non-parametric structural equation modeling?

I have been reading some work from Judea Pearl which is very excellent. In his papers, he suggests that "non-parametric SEM (structural equation modeling)" is a way of estimating associations from ...
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4answers
2k views

Are deep learning models parametric? Or non-parametric?

I don't think there can be one answer to all the deep learning models. WHich of the deep learning models are parametric and which are non-parametric and why?
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1answer
35 views

Correlation coefficient for dichotomous and continuous variable that is not normally distributed

I'm evaluating a survey and want to test the correlation of independent variables and I do not know which test / coefficient I can use as the variables have the following properties: dichotomous ...
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0answers
32 views

Are there nonparametric generative models for datasets?

Typically when I see generative models, e.g., Latent Dirichlet Allocation (JMLR) or Linear/Quadratic Discriminant Analysis (wikipedia LDA), they are probabilistic models that belong to the exponential ...
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1answer
42 views

Usefulness of MISE

I'm currently in a class on nonparametric smoothing, and, while talking about density estimation in general, the professor introduced the notion of MISE (mean integrated square error): $\text{MISE}\...
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16 views

Proof by contradiction with empirical KL divergence and proportional hazards model

I am trying to replicate an existence proof for the cumulative baseline hazard function used for the proportional odds model in Kosorok's "Introduction to Empirical Processes and Semiparametric ...
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1answer
177 views

Creating groups from an extremely positively skewed population (further explanation + image in text)

Obligatory caveat: Stats neophyte, R neophyte, trying to learn more. I have daily traffic data for 3k URLs for the entirety of 2016. There is a broad cyclical seasonal trend that the majority of them ...
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1answer
314 views

Estimating conditional probability with many samples

I am confused about the estimation of conditional probabilities. Suppose I want to predict a binary outcome variable $Y = 0,1$ given $n$ categorical features $X = (X_1, \ldots, X_n)$, i.e. to ...
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1answer
56 views

Is Dunn-Sidak approach in MATLAB multcompare identical to so-called Dunn's test?

I've asked the same question elsewhere. These two articles recommend Dunn's test as non-parametric post hoc multiple comparison test following Kruskal-Wallis test. How the Dunn method for ...

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