The median tag has no wiki summary.
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Standard error of the median
Is the following formula right if I want to measure the standard error of the median in case of a small sample with non normal distribution (I'm using python)?
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5
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93 views
Percentiles of a distribution
I'm measuring error on the median of my data using bootstrapping. I would like to obtain I sigma error bars on my data, so I'm measuring the 16th and 84th percentiles of my data. Should I divide these ...
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85 views
Median + MAD for skewed data
I am trying to figure out what happens if you apply Hampel's outlier detection technique based on the median and the MAD to data that is skewed. Apparently, the advantage of Hampel's method over ...
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192 views
How to report results from Friedman's test including post-hoc results
I have performed comparison of repeated measures for a group using Friedman’s test (K-related-samples test) and additional post-hoc analysis with Wilcoxon signed-rank test and Bonferroni correction. I ...
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42 views
Machine learning Jaakkola different sized data
I have an assignment for a machine learning problem and requires me to to compute $G=\{\|X_i-X_j\| \mid (X_i,Y_i),(X_j,Y_j)\, \text{that belong to training data}\, S\, \text{and} Y_i\neq Y_j\}$. In my ...
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Is there a closed form unbiased estimator of the median of n exponential variables from their mean? [closed]
Fix $n$. Suppose $T_1, \ldots, T_n \sim Exp(\lambda)$
For $n > 1$, is there ever an unbiased estimator of the median from a sample mean?
My attempt
$$\begin{align}P(median \le x) &= {K ...
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146 views
Why does this criterion characterize the median of a continuous random variable?
If $X$ is a continuous random variable, then let
$$\min_a{\mathbb{E}\:| X - a |} = \mathbb{E}\: | X - m |$$
Why is $m$ the median of $X$?
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44 views
Distributed Median
What is the most optimum method to calculate the median in a distributed setting? I want to optimize with respect to data transmission i.e. an algorithm that finds the median across data spread across ...
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1answer
50 views
Use median for clustering, instead of average value
I have a List of Files on which I run some statistical methods to get a rating between 0 and 1.
Now i need to cluster the files for similarities. The easiest way i thought that would be is to use the ...
2
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1answer
116 views
Expectation of the sample median for symmetric distributions
Is the sample median an unbiased estimator of the population mean when the distribution is symmetric?
4
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3answers
83 views
Sampled median's accuracy
I'm working on a problem where I need to calculate the median for a very large data set (for instance, 100M values) that has a log-normal distribution. Because of the data set's size, we were ...
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1answer
41 views
What number minimises RMSD between itself and randomly generated numbers?
Let us assume that we have a random number generator given by its probability density function. Now, we need to use this distribution to generate a number that has the following property. It minimises ...
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1answer
209 views
Comparing distributions as opposed to medians?
Assume a hypothetical scenario of two events. During event 1, I observe a set of values $[X_1, X_2,X_3,...,X_n]$. A physical phenomena occurs and this triggers event 2 for a short period of time and I ...
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40 views
Comparing tests for staging cancer
I am comparing 4 different tests for the evaluation/identification of cancer. One is a continuous variable yielding cut-off values based on both the mean and the median of 5 consecutive measurements ...
3
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1answer
79 views
Median Averaging and Error Analysis
I am not sure if i should be asking this on the Mathematics of Physics Stack Exchange site.
I am taking data for a physics research application and have a question about using median vs. mean ...
5
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1answer
58 views
Software for median polishing
Is there any easy-to-use software for Tukey median-polishing rows and columns with lots of missing values?
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1answer
198 views
How to calculate median of distributed data?
How to find the median (or approximate median) of n chunks of values. The values in each chunk can be assumed to have been sorted if it helps. In addition, the existence of a histogram for each chunk ...
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1answer
292 views
Central limit theorem for sample medians
If I calculate the median of a sufficiently large number of observations drawn from the same distribution, does the central limit theorem state that the distribution of medians will approximate a ...
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1answer
213 views
Measure of variation around Median
Are there terms for measures of variation around the median? I know that we use "variance" for means of data but how can variance be defined for the median? Is there a similar statistic for median?
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1answer
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What are the multidimensional versions of median
What are the multidimensional versions of the median and what are their pros and cons? I confess this doesn't have a single answer, but I think it is a useful question to ask and will be a benefit to ...
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366 views
Variance of sample median
Given a sample of n units out of a population of N, population median can be estimated by the sample median.
How can we get the variance of this estimator?
2
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1answer
68 views
When are tertiary splits un/justified?
I'm studying neuroscience and have a question about presenting some data. I would like to know if tertiary splits are acceptable when the variable in question is normally or not normally distributed. ...
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2answers
95 views
Advanced procedures using the Median statistic
With the risk of asking a duplicate question (to be fair, I looked at 10 pages):
Could you name and explain some advanced procedures which make use of the median statistic?
Background: I am ...
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1answer
89 views
Calculate one median for data from five experimental repetitions
I have an experiment that produces a few thousand data points which I then have repeated 5 times. Now I wonder how to calculate one single median to summarize all of them.
I could combine the data ...
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1answer
121 views
Testing median, and distribution of Binomial
Given the median is $m>0$
We have $n$ random variables: $Y_1,Y_2,..,Y_n$
If we observe a value above $m$ then $Y_i=1$ if we observe a value below $m$ then $Y_i=0$
The probability of getting an ...
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61 views
Power Calculations for Median in a Clustered Trial
I'm currently performing power calculations for an NGO wanting to evaluate a sanitation program. They've asked us to look at the distributional effects of their intervention. I know that I can appeal ...
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1answer
238 views
Is bootstrapping a valid method to assess the uncertainty of the median estimate?
Bootstrapping works well to access the uncertainty in the mean estimate, however I remember reading somewhere the bootstrap does not do a good job in assessing the uncertainty in quantile estimates ...
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290 views
Explanation for confidence interval for quantile with small data set
From one of the answers in this post, Confidence interval for median, I have found a way to get a confidence interval for a quantile, and my understanding is that this is an appropriate method for ...
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2answers
417 views
Two sample t-test vs regression
I would like to examine the difference in forecast error between year 1 and 2. The descriptive statistics show that the mean of forecast error is higher in Year 2 but the median is lower. Under what ...
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1answer
1k views
How to draw mean, median and mode lines in R that end at density?
I have drawn a skewed distribution, using these commands:
...
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1answer
434 views
What is the advantage of median polish over the median?
I still can't figure out the advantage of median polish over a regular median for the summarisation of probe to make probesets in microarray analysis.
As I understand from here the idea is to use the ...
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1answer
240 views
How to best represent median proportions using stacked bar charts?
I have a large dataset with several responses about an organization's labour costs. I would like to represent this data graphically. Typically what we do is provide a stacked bar chart (using R) of ...
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1answer
137 views
Using MAD as a way of defining a threshold for significance testing
If I have a set of terms each term having a particular frequency associated with it (the number of the times the term has appeared in fixed corpus of papers), then is the following method of ...
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0answers
34 views
Nonintegral (and not half-integral) median
I was recently looking at the National Survey of Family Growth (US Census Bureau) and noticed that the numbers on the median column were not whole numbers, but rather numbers like 5.1 and 4.6. (Not ...
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294 views
Mean$\pm$SD or Median$\pm$MAD to summarise a highly skewed variable?
I'm working on highly skewed data, so I'm using the median instead of the mean to summarise the central tendency. I'd like to have a measure of dispersion
While I often see people reporting mean ...
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1answer
448 views
Beginner's question—Dealing with ordinal data (scoring of a medical effect)
I'm a biology PhD student dealing with ordinal data (scoring of a medical effect: 0–3 points) for the first time and I'm looking for information regarding differences in treating ordinal numbers in
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Filling NAs in a dataset with column medians in R
I have a massive dataset with titles across the top for the row.
All the values in the dataset are number minus about 50 of them which are NA.
I need to find the median of each column whilst somehow ...
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2answers
149 views
Better method to estimate gender gap: difference between medians or median gap by occupation?
I'm doing some analysis of Bureau of Labor Statistics data on wages earned by men and women, and I'm trying to determine which of the two methods I've used is the better estimate of the gender wage ...
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1answer
99 views
Determine whether a number “fits” with a group of numbers
I need to determine if a single number "fits" with a group of numbers. All the numbers will be percentages, so we'll use decimals.
For example:
The group is: ...
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1answer
128 views
Variance of median from the mixture distribution
Consider iid samples from a fixed distribution function $F(x)$ and consider its median. Now consider another median from iid samples where one half is drawn from $F_1(x)$ and the other is drawn from ...
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How to construct a 95% confidence interval of the difference between medians?
My problem: parallel group randomized trial having a very right-skewed distribution of the primary outcome. I do not want to assume normality and use normal-based 95% CIs (i.e. using 1.96 X SE).
I am ...
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Why is the arithmetic mean > median on a histogram skewed to the right?
I am fairly new to statistics.
Currently I am into (histograms) medians, arithmetic mean and all the general basics.
And I came accross the fact/rule that the arithmetic mean is (always) larger than ...
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1answer
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Why is the expected value of the number of trials before the first success larger than the number of trials with a 50% probability of success?
For a Bernoulli distribution with parameter p, the number of trials with a 50% probability of at least one success is about (1/p) * ln(2). But the expected value of the corresponding geometric ...
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How does one derive the Fisher-consistency correction factor for Rousseeuw and Croux's $S_n$ (and $Q_n$)?
In "Alternatives to the Median Absolute Deviation" (Rousseeuw and Croux, J. Amer. Statistical Assoc, 88(424), 1993, pp.1273–1283) and a few other papers from the same authors published in ...
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1answer
969 views
How does the expected value relate to mean, median, etc. in a non-normal distribution?
How does the expected value of a continuous random variable relate to arithmetic mean, median, etc. in a non-normal distribution (eg. skew-normal)? I'm interested in any common/interesting ...
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Breakdown point of weighted median
I posted the same question on math.stackexchange, but haven't got any reply. So I will try my luck here:
In the context of robust statistics, there is the concept of breakdown point, which basically ...
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142 views
Expression for the median of a sum of half-Cauchy random variables
This is a technical problem I encountered in research. Sorry if it reads simple for professional statisticians.
Let $X_1, \cdots, X_n$ be iid standard Cauchy random variables. What estimate or exact ...
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127 views
Length weighted median
In the field of genome assemblies in biology (the problem being reconstructing the genome from many, short random pieces of it, where a genome is one or more long strings of a limited alphabet), there ...
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How to compute median in an online fashion? [duplicate]
Possible Duplicate:
What is a good algorithm for estimating the median of a huge read-once data set?
Imagine you have a large, multivariate dataset that resides on disk.
Are there any ...
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2answers
442 views
How do I sort an ordinal list of user-generated ratings data?
The Ubuntu Software Center uses a 1 to 5 star rating system for its App Reviews. However, it's current ratings sorting algorithm looks very fishy. I believe this is a different question from this ...
