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Questions tagged [ties]

Ties refer to equal values observed in the data. When multiple, ties can pose a problem for some methods of data analysis.

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9 views

How to adapt softmax model to tied outcomes

Consider the Harville model for modeling ordered outcomes: you observe a contest between $n$ participants, and model for each of them a $\mu_i$ such that the probability that the $i$th participant ...
21 views

How does one apply hierarchical agglomerative clustering when multiple positions are equidistant (non-unique distance matrix)?

I have been following this single/minimum -linkage example to better understand hierarchical agglomerative clustering. I noticed that the entries of d_ij are unique ...
39 views

How does Normal approximation work when ties exist for Wilcoxon Signed rank test?

I ran wilcox.test() in R (outcome variable was a test score and the data was paired samples) and got a warning message saying that it cannot generate a p-value for tied values. I saw the R document ...
616 views

Ties in a two-sample Kolmgorov-Smirnov test

This question is somehow connected to this one. I am performing a two-sample KS test in R and I think I have not fully understood the issue of the ties. Reading the help: ...
34 views

Is a kernel density estimate meaningful if > 25% of my data are duplicates?

The title pretty much says it all. I have data that consists of 80 samples but there are always at least four samples that have exactly the same value. I want to assess, whether the data is unimodal. ...
24 views

313 views

Wilcoxon Signed Rank test and reporting ties

In writing up results for a Wilcoxon Signed-Rank test, do you have to state if there were no ties in the data? Also, should the Z statistic be reported if the sample size is < 20 ? Thanks!
131 views

Exact Null Distribution with Ties

I am interested in deriving exact null distributions for small-sample test statistics with non-trivial ties. Not fundamentally continuous variables that happen to have a few repeated values, but ...
2k views

Kendall’s tau-b version calculation steps with tied ranks

I am trying to calculate Kendall’s tau coefficient for example given by Scipy in python. It is for tied ranks with tau-b version. The tau should be -0.47140452079103173 but I get a different result. I ...
446 views

Slight inconsistency between the Kruskal-Wallis built-in R function and manual calculation

I'm confused by the following, and I haven't been able to dig up the answer elsewhere. I'm trying to learn R while doing some statistics, and, as an exercise, I try to double-check the results of ...
1k views

Autoencoders' gradient when using tied weights

In autoencoders when using tied weights, it was mentioned the gradient with respect to w is the sum of two weights. I didn't understand this, can someone elucidate this. it is mentioned here on slide ...
712 views

Different methods for finding spearman's coefficient produce diff p-values depending on presence of tied values

I'm hoping someone can shed some light on the discrepancy between the p-values obtained from two different functions in R for conducting a spearman's test. The two tests produce the same p-values in ...
15k views

“Ties should not be present” in one-sample Kolmgorov-Smirnov test in R

I am going to use the Kolmogorov-Smirnov test to test normality of MYDATA in R. This is an example of what I do ks.test(MYDATA,"pnorm",mean(MYDATA),sd(MYDATA)) ...
56k views

Understanding Kolmogorov-Smirnov test in R

I'm trying to understand the output of the Kolmogorov-Smirnov test function (two samples, two sided). Here is a simple test. ...
2k views

Autoencoder with tied weights: bias?

For some unsupervised learning problem, I need to train an autoencoder, so that I only have to store the encoder afterwards. However, I am not sure on how and if the bias weights can be tied. To make ...
182 views

Kruskal-Wallis: how to handle ties that might not be really ties?

I have data from a mass spectrometer that are precise to 6 decimal places and range from 0.1 to 10. However, some items cannot be measured by the mass spectrometer because they are "below the limit of ...
2k views

adjusting ties for kruskal.wallis

I would like to compare the means of three groups using the Kruskal Wallis test in R. My data looks like this: ...
5k views

Understanding warning message “Ties are present” in Kruskal-Wallis post hoc

I'm running post-hoc comparisons after a Kruskal-Wallis test. I'm using the PMCMR package. ...
7k views

Kolmogorov-Smirnov vs Mann-Whitney U When There Are Ties

I have a dataset consisting of rank data, some 100 cases and 2 groups. (The 2 groups contain about 1/3 and 2/3 of the cases.) I would like to test whether the two groups differ with respect to median ...
15k views

ks.test and ks.boot - exact p-values and ties

I am confused by the behaviour of ks.test (package stat) a) in the presence of ties and b) if one-sided while doing a two-sample test. Documentation: "Exact p-values are not available for the two-...
727 views

How to estimate Savage scores of tied ranks

I want to calculate the Top-Down Concordance coefficient that quantifies the agreement between two rankings by emphasizing more on the lowest rankings. The original paper is: R.L. Iman and W.J. ...
95 views

compare binary responses with ties

Suppose I am testing two drugs, I and II. The response profile is either I > II, I < II or I = II. I was trying to figure out if I is in fact better than II. One way I thought of was to throw out ...
643 views

Nelson-Aalen estimator and interval censoring/tied events

I just noticed that the Nelson-Aalen estimate of the cumulative hazard changes depends on the existence of tied events. As a toy example, consider a study with 3 patients. The patients die on day 1, 5,...
25k views

Dealing with ties, weights and voting in kNN

I am programming a kNN algorithm and would like to know the following: Tie-breaks: What happens if there is no clear winner in the majority voting? E.g. all k nearest neighbors are from different ...
1k views

Mann-Whitney test with ties

I have two data sets with PDFs roughly like this: $$p(x) = \left\{ \begin{array}{lr} .75 & x = 0\\ \text{Lomax}(x) & x > 0 \end{array} \right.$$ i.e. it's ...
8k views

Is there an alternative to the Kolmogorov-Smirnov test for tied data with correction?

I've got a bunch of data from two samples (control and treated), each containing several thousand values which are to undergo significance testing in R. Theoretically, the values should be continuous, ...
24k views

How does ties.method argument of R's rank function work?

I am using rank(a, ties.method="max") to rank a. But I am not quite sure what does ties.method="max" do. Can you please help?
670 views

Cluster analysis with ties issue

When I perform cluster analysis in SAS, the SAS log sometimes return a warning something like this: ...
759 views

Ties in the data

Are there any "good" ways to eliminate the effects of ties in a data set for statistical analysis? For example, in finding the correlation between two series which has lots of ties? I would like to ...
5k views

Why are ties so difficult in nonparametric statistics?

My nonparametric text, Practical Nonparametric Statistics, often gives clean formulas for expectations, variances, test statistics, and the like, but includes the caveat that this only works if we ...
1k views

Is it wrong to jitter before performing Wilcoxon test?

I wrote a script tests the data using the wilcox.test, but when I got the results, all the p-values where equal to 1. I read in some websites that you could use ...
359 views

What to do about ties in voting results?

Imagine a committee of people in charge of hiring a CEO. A committee member can vote "No hire" (+0), "Maybe"(+1), "Hire"(+2) for a potential CEO candidate. Each CEO is scored based on the votes, and ...
9k views

Survival analysis: continuous vs discrete time

I am confused about how to decide whether to treat time as continuous or discrete in survival analysis. Specifically, I want to use survival analysis to identify child- and household-level variables ...