Questions tagged [ranks]

Ranks are ordinal numbers of the quantitative data values sorted ascendingly or descendingly. Various methods to assign ranks to equal values (ties) exist. Transform of values to ranks is often done in nonparametric data analysis. (Not to confuse with [ranking] task..) (See related: [order-statistics])

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13
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2answers
3k views

Why is the Mann–Whitney U test significant when the medians are equal?

I've received a results from a Mann-Whitney rank test that I don't understand. The median of the 2 populations is identical (6.9). The uppper and lower quantiles of each population are: 6.64 & 7....
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Is there a two-way Friedman's test?

I have ranked concentrations (from 0 to 5) of 5 different proteins from 3 different locations from the same patient. In total, 15 measures per patient and 61 patients, so 915 observations. What I'd ...
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1answer
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Rank transformed 2-way ANOVA

I know I'm asking a lot of questions these days! Sorry about that, but I'm trying to work through my grad thesis data collected over the last 4 years, and am repeatedly tripping on my beginner's grasp ...
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1answer
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Displaying Ordinal Data - Means, Medians, and Mean Ranks

I have some ordinal data that is not normally distributed, so I decided to do non-parametric testing using the Mann-Whitney U Test. I am looking at differences between groups for seven scores - these ...
7
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2answers
697 views

Equivalence of Mann-Whitney U-test and t-test on ranks

What does it mean when people say that a t-test performed on ranked data is equivalent to a Mann-Whitney U-test? Does that mean they just test the same hypothesis/are useful in the same situations or ...
8
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1answer
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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?
6
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1answer
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Are parametric tests on rank transformed data equivalent to non-parametric test on raw data?

Many non-parametric tests are identical to their parametric equivalent on ranked data. At least, that's what I learned from this blog post on Friedman's test and skimming this 1981 article.. This ...
4
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2answers
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Algorithm and R code for dealing with ties in Wilcoxon rank-sum test

I think one of the algorithms used to handle ties for the Wilcoxon rank-sum test (a.k.a., Mann-Whitney U test) is Streitberg / Rohmel. I could not find a good source which explains the algorithm / ...
2
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1answer
682 views

Rank data from 1 to N (N may not be equal to number of elements in the dataset)

I calculate percentile ranks based on the method at http://www.psychstat.missouristate.edu/introbook/sbk14m.htm I need to assign ranks to a dataset where ranks are ...
2
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2answers
73 views

Can I use multiple regression on a ranked response variable as a significance test for multiple covariates?

This blog post illustrates the relationship between inference tests on groups (t-test, ANOVA, etc.) and equivalent linear models. It also claims that for reasonable sample size, regression of a ranked ...
2
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1answer
314 views

Equivalent to K-S test on discrete data with uneven quantization

I have some data resulting from a simulation that consists of several groups, each containing a single real datapoint and a variable number of matched controls. I take the rank of each real value ...
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0answers
425 views

ANOVA on ranks?

Once in a statistics class I've seen the suggestion that one non-parametric approach for ANOVA would be to perform the ANOVA analysis on the ranks of the original data (basically as an alternative to ...
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1answer
345 views

What is a one-way ANOVA on the ranks of the observations

While reading this link: http://www.statsdirect.com/help/Default.htm#nonparametric_methods/kruskal_wallis.htm, I came across the following: ...
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0answers
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Get final rank from ranked list [duplicate]

i got exactly same problem with this question Overall rank from multiple ranked lists but i didnt get any references and answer for that. example : ...
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Creating a model to interpret numerical scores

Good morning/afternoon everyone, first of all thanks to all of you for the valuable insights provided. I will be oulining here my current challenge, trying to provide as much detail as possible. ...