Questions tagged [nonparametric]
Procedures that rely on relatively few assumptions about underlying probability distributions.
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Appropriateness of nonparametric bootstrap methods to assess difference between two groups
This question is motivated by the discussion of this earlier question.
I have two samples $X$ and $Y$, where both samples have $n$ elements. Both samples represent optimal solutions returned from two ...
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10 views
How to calculate log-rank test statistic
Depending on which statistics text you read you will get 2 different formulations of the log-rank test statistic. In some texts you will see it specified as:
$$
\frac{(O-E)^2}{E}
$$
Example 1
Whilst ...
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15 views
Group comparison for bivariate distributions
For two groups A and B that consist of n and m individual samples. Each individual sample has a unique 2-dimensional joint probability density functions (PDFs)of two variables. These PDFs are ...
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1answer
12 views
Chi-Square 2x2 Contingency vs z-test for two proportions: parametric or non-parametric?
Chi-Square Test
I think it is generally agreed upon that the Chi-square test (specifically, the chi-square test for a 2-by-2 contingency table) is a non-parametric test. (Though there is the ...
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4 views
normality and selection of analyse
In a study of comparison between 3 groups, if some of my data sets are normally distributed and some are not, should I analyse my data using parametric test or non-parametric or a mixture of both ...
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36 views
Scope for a thesis - research on non parametric statistics
I got a set of sales data which is masked and white labeled for my undergraduate thesis. I'm interested in estimating the density of the sales data available using non-parametric techniques. (...
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1answer
31 views
Wilcoxon-Mann-Whitney test for two independent samples
This is my first question on this side, so please don't mind if not everything is correct :)
I'm currently trying to understand the Wilcoxon-Rank-Test/Mann-Whitney-Wilcoxon Test, but it got me kind ...
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12 views
confidence band for empirical distribution function [closed]
I have a problem to compute and plot Kolmogorov 90% confidence band for the distribution F(x). I know that ecdf.ks.CI in R provides 95% confidence bands.
But I do not know a function for 90% level. Do ...
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3 views
Testing participants responses to different types of service provision
I have a group of survey participants who have rated their experience of three different types of service provider (health, charity, local government). The scale runs from never to always. Under each ...
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13 views
r - How to use Aligned Rank Transformed ANOVA for 2x2 non-normal data?
I'm a complete novice to stats and r so kindly bear with me.
I'm testing to see if the moisture content in two plants (p and s) is affected by heat (cold and warm). The 2x2 factorial data mandates a ...
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16 views
The limit distribution of Wilcoxon signed rank statistic?
An alternative representation of the Wilcoxon signed rank statistic $V$ is
$V=\sum_{i\le j}\mathbb{I}_{\{X_i+X_j>0\}}=\sum_i\mathbb{I}_{\{X_i>0\}}+\sum_{i<j}\mathbb{I}_{\{X_i+X_j>0\}}$
...
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18 views
Fitting distributions using the dispersion of Z-scores
I work for a medical testing company and I've inherited some legacy code written by someone who has since left. I understand the reasoning behind most of what is there, but the final step is something ...
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1answer
28 views
Are there any non parametric tests to check for Pareto data?
I'm in search of a non parametric test to check whether my data are Pareto distributed, but I couldn't find a proper reference for it. I'm using R to simulate these so if there's any R in built test, ...
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17 views
Why is “consistent nearest neighbour” Non-parametric? [duplicate]
Definition of "Consistent nearest neighbour", runs our usual KNN classifier
but instead of viewing k as a hyper-parameter it always sets k = ceil[log(n)].
So far, I looked-up many references and ...
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5 views
How is the equation for minimum sample size when using maximum and minimum sample values for nonparametric two-sided tolerance interval derived?
So the equation in question is
$1-\alpha = 1-np^{(n-1)}+(n-1)p^n$
I have seen it in multiple textbooks but none of them shows how it's derived.
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9 views
Measuring equivalence/reliability (ICC and consorts)
For a reliability study I’m administering patient reported outcomes (questionnaires) with 2 modes of administration (on paper and via an electronic device). I’d like to measure equivalence/reliability ...
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6 views
Parametric estimator for straightforward interval-censored data
$X_i$ is iid from some distribution, such as $N(\mu, \sigma^2)$. All I want is to estimate the parameters of the distribution. However, I don't observe $x_i$, instead, I observe $(a_i, b_i)$ such that ...
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15 views
Confused about the statistical tests to choose or any transformation to apply
I am new to the stackexchange, so please forgive me for my editing ignorance. I am confused and stuck about how to proceed further with my data. I have the following data
...
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24 views
Kolmogorov–Smirnov test on text data
The Kolmogorov–Smirnov test a very efficient way to determine if two samples are significantly different from each other or whether the CDF between two different samples fit each other. This can be ...
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0answers
29 views
Rank non-normally distributed sets of integers: long read sequencing and phase blocks
I have about 20 arrays of empirical integer values, which are each not normally distributed, with long tails. I am looking for a 'sane and sound' metric on how to sort these distributions, "with ...
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7 views
Analysis for a Within-Subjects Design with Ordinal IV and Continuous DV
I have a set of non-normal data I'm trying to analyse but am worried I'm violating the assumptions of my chosen test. I have a 18-trial within subjects experimental design. Participants received an ...
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1answer
30 views
I need to use a Wilcox Sign Rank test with unequal sample sizes
I'm analyzing a before and after treatment of farm fields based on runoff from rainfall events. Over 6 different farm fields there were 136 water samples from before the treatment was installed and ...
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1answer
44 views
Expectation of a square of a sum
Let $X_1,\cdots,X_n$ be i.i.d. random variables with density $f$ and let $\hat{f}$ be an estimator of $f$.
Is the following inequality direct from the standard properties of expectation and sup-norm?
...
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32 views
Non-parametric estimation
This is some sort of an initial question may be I'm asking which may not have a fixed, straightforward answer. But this is very unclear to me. I have come up with some parameter estimation methods for ...
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1answer
24 views
non-parametric alternatives to anova
Hello I am doing some stats on some research I did and was having trouble picking the correct statistical tests to use.
The question I am trying to answer is, I have two cell types (I, II) and two ...
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6 views
Predictors significance and interpretation in kernel methods (and Gaussian processes models)
Assuming one would want to evaluate the "significance" of features in non parametric model as GP (regression).
Opposed to (linear) SVM or LDA, in which one would be able to somehow "interpret" the ...
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101 views
Parametric vs non-parametric machine learning methods
I looked-up many references and websites and researched on how to determine if a method is between parametric or non-parametric. I came up with below definitions,
A parametric algorithm has a fixed ...
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33 views
Derivation of AMISE and Bandwidth
Given:
Let $K(\cdot)$ be a bona fide kernel. Let $f$ be a pdf and $\widehat{f}_n$ is kernel density estimator with bandwidth $h$ based on a sample $X_1,X_2,\cdots,X_n$ of size $n$ draw iid from $f$. ...
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1answer
241 views
Rank ANCOVA is a bad idea?
I am currently working on a project looking at the best way to handle missing data (such as quality of life) due to death. One approach is to use categories/ranks for the outcome, where death is the ...
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0answers
12 views
Contribution of a predictor in Nonparametric regression
Is there an equivalent to a beta weights in a nonparametric regression?
I am using the NP package in R and running a local linear regression where my bandwidth estimates are produced using least ...
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1answer
52 views
Properties of Kernel Density Estimators
Given
Let $X \in \mathbb{R}$ be a real-valued random variable with theoretical probability density function (pdf) $f(x)$ and corresponding cumulative distribution function (cdf) $F(x)$. Let $X_1, X_2,...
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25 views
Non-parametric alternatives for a three way nested ANOVA?
I am a student working on a graduate degree in the natural sciences. I am looking for advice on generals approaches and examples (R code and example data) which I might be able to follow to get ideas ...
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16 views
How to calculate the significance of a pairwise comparison distribution?
I have a variable ($X$) that depends on two parameters (say $P$ and $Q$), each of which can take six values each ($P_1\cdots P_6$ and $Q_1\cdots Q_6$). I take pairwise values of each parameter like $...
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1answer
60 views
How to estimate the confidence interval of the difference of means?
I have two sets of measurements (repeated measurements of two processes, let's call them $X=\{X_i\}_{0...n}$ and $Y=\{Y_i\}_{0...m}$), and I would like to estimate (with confidence interval) the ...
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57 views
Nonparametric for lmer
I am trying to fit a model based on the df dataframe, where I want to be able to compare all of the levels between/within the treatments (...
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1answer
39 views
Which statistical test for my data?
(EDIT: question simplified)
This is a basic question, since I am new to data analysis and statistics.
I am carrying out a 2X3 factorial survey where participants are presented with a series of ...
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12 views
Guidelines for interpreting Success Rate Difference from a Mann-Whitney U test
A reviewer recently asked me to perform a Mann-Whitney U test on some grouped data and to obtain a Success Rate Difference (SRD) as a measure of the size of the effect. This is the output of the Mann ...
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11 views
Compare categorical variables that are not(?) independent
I have some survey data in which respondents were classified in to two overlapping groups (i.e. respondents who work in a profession and people who do this same work on their own-- many people do ...
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24 views
Non-Parametric Effect Sizes and Power
As my data was extremely skewed, I have ran 2 non-parametric tests: a Mann-Whitney U and a Wilcoxon Signed Rank test.
I have read that using Cohen's D as an effect size for such tests is not ...
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20 views
Comparing one group with others when repeated measures with non-parametric tests corrected for multiple comparison
I have a reference method $M_{ref}$ that I would like to compare with other methods $M_1$, $M_2$, $M_3$ when taking measurements (denoted scores from now on) from a data sample of size $N (N > 30)$....
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11 views
Largest connected group of identically distributed nodes in d.r.v sample graph
I have come across an unfamiliar and somewhat interesting problem while attempting to write an algorithm for an image processing application and was wondering if any of you had any ideas that might be ...
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1answer
22 views
Does statistical significance impact uplift calculation for marketing campaign
I'm trying to understand 2 things in relation to calculating uplift from a marketing email campaign:
Impact of statistical significance
Impact of highly skewed data on calculating uplift
The ...
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1answer
67 views
variance of nonparametric estimator of mean
I'm having some trouble with understanding how to calculate the variance of a non-parametric estimator.
The example comes from Wasserman's "All of statistics book"
Let $X_1, \ldots,X_n \sim \text{...
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17 views
Testing data samples(vectors) if they came from the same distributions
I've found whole bunch of tests here for non-parametric statistics:
Nonparametric_statistics
But since I'm not good at statistics: do those tests work only for random variables?
I have two sources of ...
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2answers
34 views
Appropriate statistical test for data which do not have normally distribution and do not have equal variance
My data has 150 samples and is not normally distributed, and it does not have equal variances either. I know t-test (e.g. this python method) can be used when data is normally distributed and it can ...
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11 views
Formula for Power of Upper Tail Sign Test
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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10 views
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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1answer
35 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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0answers
42 views
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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21 views
Using non-parametric transformation (ranking) on 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 ...
