# nonparametric's questions - English 1answer

1.238 nonparametric questions.

### 11 How do I perform a regression on non-normal data which remain non-normal when transformed?

7 answers, 57.272 views regression distributions nonparametric
I've got some data (158 cases) which was derived from a Likert scale answer to 21 questionnaire items. I really want/need to perform a regression analysis to see which items on the questionnaire ...

### What are the implications of asymmetry in the Wilcoxon signed-rank test?

I have samples $a$ and $b$ from pre and post treatment conditions on same participants. The empirical distributions of both these samples are skewed positively. The paired differences $a_i-b_i$ do not ...

### How to choose the correct sample and hypothesis test for spatiotemporal observations?

Consider the following scenario: There exist $N=10$ participants in a study. Each participant $i$ is monitored under baseline conditions and later under experiment conditions. That is, the baseline ...

### 2 How to graph Wilcoxon test power R

I've been trying to calculate and graph the correspondent power for the wilcoxon signed test and haven't had any luck. I tried simulating two normal distributed samples, apply the wilcoxon test and ...

### What happens to the Brown-Forsythe test when the data is weighted?

0 answers, 4 views nonparametric heteroscedasticity
I wish to run a Levene and Brown-Forsythe test to determine whether its safe to assume that different groups have the same variance of a given variable (say variance of wages across different regions ...

### 2 Paired t-test of medians

I need to run an inferential test on some large data where the individual data points have a heavily skewed distribution. I'm considering doing a paired t-test across a number of days comparing the ...

### 9 Test if multidimensional distributions are the same

2 answers, 3.025 views r distributions nonparametric python
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 ...

### 6 Nonparametric nonlinear regression with prediction uncertainty (besides Gaussian Processes)

What are state-of-the-art alternatives to Gaussian Processes (GP) for nonparametric nonlinear regression with prediction uncertainty, when the size of the training set starts becoming prohibitive for ...

### 84 How to choose between t-test or non-parametric test e.g. Wilcoxon in small samples

Certain hypotheses can be tested using Student's t-test (maybe using Welch's correction for unequal variances in the two-sample case), or by a non-parametric test like the Wilcoxon paired signed rank ...

### 8 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 ...

### 1 Meaning of “a test task is nonparametric or parametric”?

How is a test task being nonparametric or parametric defined? My understanding is that the test task is parametric, if and only if it assumes a parametric model on the distribution of the sample, ...

### 4 Surface Fit Using Tensor Product of B-Splines

I am trying to teach myself surface fitting with splines using tensor products. I am trying to construct a toy example but I can't seem to get my example to work. I will try to explain the best I can ....

### Reporting values from generalized estimating equations with dependent variables having over two values

0 answers, 13 views nonparametric odds-ratio gee
I am using SPSS for generalized estimating equations including rather skewed variables. Now I am just curious as to how I should interpret and report my results. I have seen several papers using GEE ...

### Non-parametric ANOVA alternative with 10 independent dichotomous variables

0 answers, 29 views anova nonparametric paired-data
I am looking to pick an appropriate statistical model to generate an output similar to the ANOVA hourly wage example in https://en.wikipedia.org/wiki/Dummy_variable_(statistics). However, in my case: ...

### 1 Dealing with very small samples with different shapes

1 answers, 41 views anova nonparametric
I have two groups with very small sample sizes (just 6 obs per each group).It seems that There is a violation of normality and Homogeneity of variances (based on Plots). Now I was wondering if I can ...

### 3 Difference in means statistical test for non-normal, heteroscedastic data?

Suppose I have a data set with three or more groups. After some exploratory data analysis, I find that The groups do not come from a normal distribution the variances within the groups are not equal,...

### 1 Nonparametric test for trend using Python

I am looking to perform a nonparametric test for trend on a continuous outcome across three groups, preferably in Python. For example height (pretend height is not normal) in 4th, 5th and 6th graders....

### 2 Non normal residuals for Tweedie GLM

I am using Tweedie GLM as my data contains exact zeroes. However, my stats is weak and want to confirm a few things. Does Tweedie GLM assume normality of residuals? Is shapiro.test() the way for ...

### 1 Non-Parametric Regression with Ordinal Independent Variables

0 answers, 740 views r regression nonparametric ordinal-data
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 ...

### Change in insect community over time using PERMANOVA, should i include nested effect and how to interpret my results?

I have a data set of an insect community composition (17 insect species, raw abundance data, sampled 5 times over 60 days within 24 tanks (4 replicates). There were 3 treatments (free fish, caged fish,...

### 1 are there any nonparametric forecasting methods?

Are there any good statistical non-parametric forecasting methods besides machine learning methods like neural networks/decision trees etc. for time series analysis ? If so, are there any R packages ...

### 1 Why use parametric test at all if non parametric tests are 'less strict'

I have read from several sources, even in my undergrad courses, that parametric tests require the data to have a certain distribution, for instance normal, whilst non-parametric don't. I have ...

### differences in forecast and reconstruction in SSA, in R

I was playing around with the Rssa when I discovered this: Firstly: I created to sequences:library Rssa x<-1:100 x1<-1:80then the corresponding function:...

### 1 Cross-validation when there are near-duplicates in the data

I use cross-validation, with random partitioning, to test the generalization power of a certain classifier (a short-sentences classifier). The problem is, my dataset contains many almost-identical ...

### 4 Estimating the gradient of log density given samples

I am interested in estimating the gradient of the log probability distribution $\nabla\log p(x)$ when $p(x)$ is not analytically available but is only accessed via samples $x_i \sim p(x)$. There ...

### 1 In general which runs test is more powerful?

There are several tests for randomness, one is runs up and down, another is run against mean or some other values, of cause, Bartel's rank test can also be used. There are studies shows where Bartel'...

### 5 Non-parametric alternative to simple t-test

3 answers, 421 views t-test nonparametric levenes-test
I have five numeric variables of two populations (each of them with 60 individuals) and for each of those five variables I want to know if there is difference in the means. I was trying to use a ...

### Non parametric test [duplicate]

guys. I wanted to assess whether there is a significant difference between the means of three independent groups or not, but I cannnot use t test for them because the sample sizes are vastly different....

### 1 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 ...

### 1 Intuition: What is the difference between linear factor models and regular linear regression?

So, I have a very vexing theoretical question that I hope some experienced econometricians can help me with. Being in finance, I have recently been exposed to linear factor models, which are models ...

### 1 Data Simulation weighted average [closed]

0 answers, 34 views nonparametric simulation
is it possible to simulate data, that follow: $Y_i = \sum_{j \neq i} w(i,j)\cdot Y_j +\epsilon_j$ So that $Y_i$ is a weighted average of all other $Y$'s? I'm thinking about this for a few days and ...

### 1 Can I assess the relationship between a normally and non-normally distributed variable?

My study is related to the visual attractiveness of route-plans in a logistics context. In practice, route-plans are rejected based on the fact that they "do not look nice". I have conducted an ...

### 2 Excepted conditional density and conditional expectation

1 answers, 102 views regression nonparametric pdf
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 ...

### 6 Friedman test and post-hoc test for Python

3 answers, 3.202 views python nonparametric post-hoc gee friedman-test
In my dataset, I have five (ordinal) groups with an x-amount of measurement. Because homoscedasticity is violated, I performed the Friedman chi-square test to see if there are any statistical ...

### 1 Smooth regression algorithms that produce zero training error

I am looking to fit three regression functions $f_1, f_2, f_3:\mathbb{R}^2 \to \mathbb{R}$. For example, let's say $X_1$ is time, $X_2$ is geographic latitude, $f_1$ is the temperature, $f_2$ is the ...

### What test for 3-level * non-normality * non equality of variance (like Brunner-Munzel test for 2-level factor)

I have no data now though, I'm learning nonparametric statistics now. As I learned so far, nonparametric test for three-level design is Kruskal-Wallis test. But Kruskal-Wallis test needs the equality ...

### 1 A' (A prime) for extreme Hit rates and False Alarms

0 answers, 29 views nonparametric signal-detection d-prime

### Group comparision in repeated measures data with missing values?

I have data from blood samples collected from 20 patients before, during (at 30 min, 1 h, 2 h, 3 h, 4 h) and after a medical treatment (using the slightly different treatment protocols A and B). The ...

### 1 Parametric spline regression after Gaussian process regression?

I'm trying to develop a (functional) model to predict the output of a computer simulation. I've run a small set of experiments, varying the 4 predictors $a$, $b$, $c$, and $d$ via LHS, and calculated ...

### 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 ...

### 2 Learn a distribution from distributions on samples [closed]

There's many good ways to learn a distribution $p_X$ of an r.v. $X$ over $k$ symbols given many i.i.d. samples $X_1,\ldots, X_n$. The simplest is to use the sample relative frequencies $\hat{f}_X$ as ...

### Approximate a CDF

Suppose we have $n$ equations with an integral of the form $\int_0^{x_i} F(z)dz = c_i,\ i=1,\ldots,n$ where $F(y)=\mathbb{P}(X \le y)$ is an unknown cumulative distribution function of a non-negative ...

### Dunn's test of multiple comparisons

From the documentation page for the R function dunnTest from the package FSA: Performs Dunn's (1964) test of multiple ...

### What does the size of the Wilcoxon rank sum test 'W statistic' indicate?

I wish to see whether the average meal masses of two species are significantly different, and I have sample sizes of >800 for both. My Wilcoxon rank sum test returns a W = 330520 value - how should I ...

### 1 2-ways anova for non-normal data

Our group took samples of contamination in sediments from around 20 non-related rivers, during 4 months. I want to know if contaminant (micrograms per liter) is related to river and/or time, thus my ...

### 8 Is there an equivalent of ARMA for rank correlation?

1 answers, 152 views r correlation nonparametric garch arma
I am looking at extremely non linear data for which the ARMA/ARIMA models do not work well. Though, I see some autocorrelation, and I suspect to have better results for non linear autocorrelation. 1/ ...