Questions tagged [nonparametric]
Procedures that rely on relatively few assumptions about underlying probability distributions.
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Comparing groups of empirical probability density functions
I'm a neuroscientist approaching doing some complex statistics and can't find anyone to point me in the right direction of what I need. I'm happy to read around the subject, I just don't know enough ...
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30 views
Properties of Nonparametric Test Statistics $B$
Given
Consider the upper tail $H_0: \theta \leq 0 \,\,\, \text{vs} \,\,\, H_a: \theta > 0$ sign test with the test statistic
$B = \sum_{i=1}^n{\psi_i}$ where $\psi_i = \mathbb{I}(Z_i > \theta)$...
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One-tailed Conover-Iman test?
I'm new to non-parametric statistics and want to do a post hoc analysis of some data after a Kruskal-Wallis test. I am using the implementation of the Conover-Iman test available in the scikit-...
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Dealing with non-parametric variables for factor analysis in R
I have been wrestling with how to simplify a set of mixed variables (some orthogonal, some numeric) some (of both types) of which are significantly skewed. I have run a factor analysis anyway and ...
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1answer
17 views
Calculating degrees of freedom in a Mann Whitney U
I have completed a series of Mann Whitney U tests in R, and am looking for the degrees freedom.
I'm comparing two datasets of n1=29 and n2=5, with StandardDev1 0.4525 and StandardDev2 0.3652.
What ...
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Algebraic Manipulations in Mann-Whitney-Wilcoxon Test Statistics
Given
Let $\Delta > 0 $ be positive real number. Consider the Wilcoxon-Mann-Whitney upper tail test $H_0: \Delta \leq 0 \,\,\, \text{vs} \,\,\, H_a: \Delta > 0$ aimed at testing the difference ...
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1answer
64 views
Do Stochastic Processes such as the Gaussian Process/Dirichlet Process have densities? If not, how can Bayes rule be applied to them?
The Dirichlet Pocess and Gaussian Process are often referred to as "distributions over functions" or "distributions over distributions". In that case, can I meaningfully talk about the density of a ...
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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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1answer
40 views
Regression for Non Normal data using SPSS/R [closed]
How can we model our non normal dataset using regression?
By using Gauss Markov theorem, we can estimate our model, but how can we test our linear model and significance of parameters?
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Unequal sample sizes for npmv
I have a similar question as this: Nonparametric test for MANOVA in R violation of homogeneity and unequal group sizes which is unanswered.
I have a dataset for which I want to perform a MANOVA. ...
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References about nonparametric regression multiple time series
I am very new to the nonparametric regression and time series.
I was wondering if there are any good references for Multiple Time Series? To be specific, I want to learn the case like
$$y_t=f(x_{1t},\...
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How to test for differences between groups for ordinal outcome variables in SPSS?
I do not have experience with ordinal data, please help me out with my questions?
I have conducted a survey which consists of 25 Likert-items, these items are all statements for certain conditions ...
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15 views
Non Parametric Test Equivalent to an ANOVA
I am looking to do a non-parametric test of a 2x2 mixed anova as my dependent variables are far from normally distributed? Any help would be great!
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19 views
Equivalence of Kaplan-Meier estimator and EM algorithm
For right-censored failure time data, in a non-parametric setting, is there an equivalence between using the EM algorithm (i.e. calculating the expected log-likelihood and maximizing) and the Kaplan-...
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Statistical test for first sample greater than given sample?
Does anyone know of a name for the following statistical test/whether there is a name/whether the following line of reasoning is just bogus?
Say I have a value $x$, and a way to generate samples from ...
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How can I calculate $\mu_x/\mu_y$ using Jackknife?
I have difficulties in calculating confidence interval using Jackknife.
Suppose that I have two independent samples and I do not know both their population distributions.
I understand how to ...
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How to decide the weight of the locally logistic regression?
I have a problem of how to decide the weight of the logistic regression. My model is as below.
For the general logistic regression, we have the likelihood of the model:
$L(\theta)=\prod_{i=1}^{m}P ( ...
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21 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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Comparing changes in pre-post count results for two cohorts
Thanks in advance!
I have a pre-post analysis Of cases and controls. The outcome variables of interest are emergency room visits and hospitalization visits - both rare occurrences with median = 0 ...
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1answer
26 views
Is there a non-parametric, two-way, continious data ANOVA for replicated repeated measures?
I have data of multiple factors. Let's call them: size (2 levels), geometry (2 levels) and time (242 levels but I can limit my focus to 3 levels, which are relevant).
I also have a measure (dependent ...
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Non-uniform p-values from hoeffd function in Hmisc when data sets are independent
When using the function hoeffd in the CRAN package Hmisc I get unusual p-values for pairs of data sets that are independent. The function hoeffd is an implementation of Hoeffding's $D$ statistic. ...
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Hypothesis testing in non-parametric regression
Say I have two processes/time series, $X = (X_{t_{1}},X_{t_{2}},\dots , X_{t_{n}})$ and $Y = (Y_{t_{1}},Y_{t_{2}},\dots , Y_{t_{n}})$ observed at times $t_i$ for $i=1,2,\dots, n$ where $0 < t_1 <...
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1answer
25 views
Can Non Parametric Tests be used on large sample size data that is not normally distributed?
Non parametric tests work great with small sample size data. Now suppose I have a large sample size of 10 million samples that are not normally distributed. Will non parametric tests work in this case?...
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1answer
15 views
How to compare rigth skewed data with non-parametric test?! Which test is the right one
Hi im trying to compare cells size from multiple locations. I have 5 biopsy locations from 25 individuals = 125 single tissue biopsies.
The cell size is aquired using digital image processing and one ...
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General way to construct a confidence interval for a unknown constant to which a sample estimator converges
Assuming that a sample estimator converges to some unknown constant (a wild assumption to be sure) and without assuming the distribution of either the sample estimator or the variables from which it ...
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2answers
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Tests of normality - qq and Shapiro-Wilk
I am new to the world of stats...
My data had a log normal distribution, so transformed by log to get it nearer normal distribution. This is real-world data.
From here I want to establish if my data ...
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12 views
Goodness-of-fit test applied to tuples in sequences/samples, instead of raw data
High level problem:
I have two sequences of data. The first one is the reference, the truth, the second is one which contains missed values (due to measurement errors). I want a test which can ...
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16 views
Sample size calculation for parametric test, with large effect expected, small numbers. Should I use parametric or non parametric tests?
I am trying to figure out what would be the best way to analyze data from a randomized double blind trial we conducted.
We sought to find if two dosages of a drug were effective for a severe symptom ...
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is the PROCESS-test in statistics a parametric or non parametric test?
This might be a silly question.
But my supervisor wants me to redo the analytical (spss) tests of my thesis, because my data is not normally distributed.
I found that there is an alternative for the ...
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28 views
Determining differences between curves with the K-S test
I'm running an experiment where my treatments have a significant and highly sensitive effect of the distribution of a result.
For example, if i alter a certain nutrient in a vegetable, the ...
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Estimating Spline curve by OLS. Is a good idea to fix the knots at Chebyshev sites?
I am writing my master's degree thesis on a novel method for fixing knots in an adaptive way and while reading the literature I've found many references to the so-called Chebyshev sites. This sites or ...
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What is a good test for whether a sample is drawn from a particular parametric family against a generalized alternative
Suppose I have some large number n of draws from a strictly positive distribution that I believe to be a member of a particular parametric distributional family. I use the draws to estimate the ...
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30 views
Derive the estimator for the integrated squared bias $\int \left(\operatorname{E}\hat{f} - f\right)^2 $
This problem is found in p. 77 of Wand & Jones' (1995) book. If you are familiar with nonparametric estimation you may skip this introduction.
Suppose we want to minimize the integrated squared ...
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23 views
non-parametric tests for repeated observations
I am looking for an RM-ANOVA alternative that fits with non-normal data that may not satisfy sphericity assumption. My dataset: Through a mark and recapture study, I trapped turtles, and collected ...
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1answer
114 views
Credibility evaluation - how to model conditional continuous density from multiple variables of various types?
I recently got dataset for 37000 households with declared income and a few dozens of other variables of various types: continuous, discrete, binary.
The task is to automatically (unsupervised) ...
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What test should one use when dealing with different treatments in plant clones?
In an experiment involving plant clones there are: 20+ treatments, 5 technical replicates for each treatment (plant clones in which the treatments were tested).
Variable of interest is Biomass.
Due ...
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Bounds for the expected value of the Kolmogorov-Smirnoff loss function
Let
$$
\mathcal{F}=\{F:\mathbb{R}\longrightarrow\mathbb{R}: \text{$F$ is the CDF of some probability measure on $\mathbb{R}$}\}.
$$
Consider the loss function, $L:\mathcal F\times\mathcal F\to\mathbb ...
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50 views
Using Mean Cumulative Function (Nelson-Aalen) to assess drug efficacy
I have a large medical retrospective longitudinal dataset of electronic health records. An individual is identified by an ID. A medical event or drug prescription event is identified using a code and ...
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Plot the exact density of a transformation of a distribution
I would like to compute (and plot) the exact density of the following distribution:
$ X_i \sim exp(-Exponential(\lambda)) - 0.5 $
I already have the estimated density for this distribution, but I ...
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1answer
31 views
Covariance of An Empirical Distribution Function Evaluated at Different Points
The problem is extracted from All of Statistics (Exercise 7.5), Larry Wasserman. I don't have a solution manual to the book so I post here the problem together with my attempted answer:
Let $x$ and $...
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1answer
43 views
Wilcoxon Test - non normality, non equal variances, sample size not the same
I know there are already a lot of posts out there, but I couldn't find this exact combination in any of them.
Comparing two samples (Prices associated with men and with women), but I have neither the ...
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9 views
Definition of a 'design adaptive' fit?
When studying non-parametric regression, I've been told that local linear fitting is often better than local constant fitting at the job of estimating regression functions because local linear fitting ...
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1answer
47 views
Why errors are written additively in a regression model?
I was curious about: Why do we write errors (or disturbance term) $\varepsilon$ as a additive term in a regression model? To elaborate, whether we consider a paramteric or non-paramteric regression ...
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9 views
comparison of two independent data of same location using statistical test
I have elevation values of a geographical area with their lattitude and longitude, derived from two different satellites. How can I compare these data using some statiscal test?
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1answer
38 views
Need for assumption of continuity of the distribution
In non parametric Inference what is the need to make the assumption that the underlying distribution of the random variable under consideration is absolutely continuous?
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For what reasons should one use Bootstrap Testing when the sample size is large?
Bootstrap testing is great if we have a small sample size where the Central Limit Theorem does not apply. However, what are convincing reasons we should use Bootstrap if we do have a large sample size....
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Computing Wassertein Distance
For two probability measures $\mu$ and $\nu$, the Wassertein Distance is defined as $$W_p (\mu , \nu) = \left[ \inf\limits_{\gamma \in \Gamma} |x-y|^p \, d\gamma (x,y) \right] ^{\frac{1}{p}} \, , $$
...
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Statistical test for binned proportion data in JMP / MATLAB
I have been trying to determine the proper statistical test for comparing binned proportional data between groups. My data set is individual subjects (4-5 per group) with 76-165 cells per individual. ...
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Pairwise non-parametric test?
I have 5 groups of patients (different sizes), for which I measured some property that is continuous but not normally distributed. I would like to compare every pair of groups in respect to this ...
