The median is the value below which half the data or probability distribution lies - when the sample size is odd, the median is the 'middle' value of an ordered sample.

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Rolling estimate of Andrews.Chen, median unbiased estimator of an AR model in R? [migrated]

Given an AR(4) process, this can be rewritten in an ADF form as In order to estimate $\rho$, that in this case represents the sum of the autoregressive parameters, there is a procedure proposed by ...
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70 views

How much sense does median of one number make?

Median of one number = the number itself. I am calculating the median price sq ft of properties of different areas based on the different data entries I have got that include their ID, area and ...
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13 views

Basic application of mean, median and percentiles [closed]

The mean salary at an island t-shirt shop is \$28,400 with a standard deviation of \$5400. The median salary is \$27,400 and the 62nd percentile is \$28,900. Is the following True or False: ...
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22 views

When the dependent variable is Median Time of a specific event, have we to use Quantile Regression or OLS Regression works well?

I am asked to make a regression model and the dependent variable is Median Time of a specific event. I think I can consider the Median Time of that event as a random variable and therefore the ...
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31 views

Calculating median for different subsets and sample sizes

I have a basic question about calculating median. The database I'm using contains registered records of criminals and the number of committed crimes per year each has committed in country X. Based on ...
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37 views

Calculating Median of Different Data Groups?

Bear with me here. I'm a newbie at this. Let's say we have this data : ...
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204 views

Is there a reliable nonparametric confidence interval for the mean of a skewed distribution?

Very skewed distributions such as the log-normal do not result in accurate bootstrap confidence intervals. Here is an example showing that the left and right tail areas are far from the ideal 0.025 ...
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74 views

When the Median Absolute Deviation (MAD) is zero

Suppose my data look like the following: (10, 10, 10, 10, 10, 0) Would it be possible to remove an outlier in this distribution using the median absolute deviation? Of course, you wouldn't need to ...
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21 views

Reducing density of outliers

I have a dataset with right skewed data. It represent frequency of candidates vs their TTB (which is essentially the number of days) Now the TTB values less than 14 or so are possible. But not ...
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37 views

Why is the 95% CI for the median supposed to be $±1.57*IQR/\sqrt{N}$?

In various sources (see e.g. here), the following formula is given for confidence interval for median (especially for the purpose of drawing notches on box-and-whisker plots): $$ 95\%\ CI_{\rm ...
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71 views

Why use a “truncated mean” (aka “trimmed mean”)?

NB: In this post, I will use the abbreviation $TM_P$ to stand for a symmetric truncated (or trimmed) mean that discards the largest and smallest $P/2$ percent of the data. In fact, for concreteness I ...
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32 views

(CDF Quantile) Understanding an example from a swirl lesson

I need to understand an explanation from a swirl() lesson in course "Statistical Inference", menu option "Probability2". At 76% of completion, there is a question: "The quantile v of a CDF is the ...
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20 views

Probability of median of numbers in a range

how to calculate the probability that median of 3 random numbers from 0 to n, that are not in [0.2n, 0.8n] ? I think it should me P(2 numbers < 0.2n) + P(2 numbers > 0.8n) + P(all numbers < 0.2n ...
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23 views

Does the asymptotic distribution of sample median follow from statistical functionals?

I know that if $F_n$ is the empirical distribution function and $F$ is the true distribution function, then, with $T$ being any statistical functional (satisfying the von-Mises derivative conditions), ...
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19 views

Statistical analysis on daily data

I have a number of data points that I am trying to extract a meaningful pattern from (or derive an equation that could then be predictive). I am trying to find a correlation (?) between RANK and DAILY ...
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18 views

median split procedure reference

Is there any reference that I might use when I mention the median split method in a paper? i.e. turning a continuous variable into a categorical one by splitting a sample into 2 (above and below the ...
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16 views

Theil–Sen estimator in R with more than one variable? [duplicate]

Can Theil-Sen be defined for multiple linear regression? If so, is there an implementation in R for it? I simply want a formula a~b+c, but the package ...
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17 views

Effectiveness of Median

New to this board and hoping this question is something easy to describe. I am working on a project that look at median cycle times of emergency department patients length of stay. Across a quarter, ...
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1answer
28 views

Filtered Data for Median - strange?

I am looking at a legacy process for work. We look at corporate budget data. The data is composed of annual budgets for different major categories for different corporate regions. The upper management ...
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1answer
73 views

Using the median for calculating Variance

I have a 1-D random variable which is extremely skewed. In order to normalize this distribution, I want to use the median rather than the mean. my question is this: can I calculate the variance of the ...
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129 views

Comparison of medians in samples with unequal variance, size and shape

What am I trying to do and how does my data look? I am trying to perform some comparisons of medians of groups of data that, most often than not, are not-normally distributed. In some cases I am ...
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24 views

How many min & max values to remove?

I imaging that the following problem is quite common, so there should be recommendations what to do. I've got multiple measurements of a certain value. Let's order these measurements: ...
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1answer
159 views

Can I get the parameters of a lognormal distribution from the sample mean & median?

I have the mean and median values for a sample drawn from a lognormal distribution. Note that this is not the mean and median of the logs of the variable, though I can of course calculate the logs of ...
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34 views

cleaning outliers based on MAD but if MAD == 0.0 then clean by STD?

I'm trying to clean outliers from my features by the following univariate method: calculate median for each feature, and nullify values that are far from it by more than 3*MAD (median absolute ...
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Is there any reason not to model group medians with a plain regression model?

Consider the Boston Housing dataset, in which the intended target/response $Y$ is actually a group median. Are there any objections to modeling this group median with a standard regression model, in ...
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37 views

bootstrapped standard error to make inference about difference of means

I have a variable showing individual wages and a categorical variable of their race (Hispanic, Asian, etc). After getting their means, medians and their respective standard errors for each group ...
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38 views

Combining sets of medians and their deviation measures

Suppose I have the following sets of estimates : $S_i = \{ (m_1,d_1), (m_1,d_1), \ldots (m_{N_i},d_{N_i}) \}, i = 1,2,\ldots P $. In each set, an ordered pair corresponds to median of a set of ...
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19 views

Recalculating mean, median, std dev and confidence interval after updating sample

I am working on an application which gets rolling samples of World of Warcraft auctions every two hours. The auctions contain, among other data: item ID (will be used to group auctions before ...
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39 views

Weighted median

I'd like to compute a median of measurements taken from a population with 3 subgroups, A, B, and C. I'd like to the median to be "weighted", in the sense that each of the groups should have equal ...
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35 views

How to take median of medians when not all are weighted the same

I've got an arbitrary list of U.S. counties, with a median income score for each one. I need the median income of all of those counties together. (I could settle for an average if need be.) I've ...
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1answer
81 views

Impute with the Mean or Median? Instrumental Variables

I am using instrumental variables and I have missing data. In r, I don't believe you can use the MICE package with the AER package. Therefore, I am going to impute with either the mean or median ...
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1answer
30 views

Possible to estimate distribution around mean given #samples, mean, highest and lowest?

For a project for which there are multiple bidders, the following is known: Number of bidders: 24 Mean bid: 104 Highest bid: 356 Lowest bid: 20 Given the above, is it possible (however roughly) ...
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78 views

If I have means and medians, is there a way to average them?

Please consider these data points as an example of many more, they represent single studies with multiple samples which have been done during the last decades. ...
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42 views

Different Central Tendency Measures for Describing Groups or Individuals

Background: I have records with various metrics for many users. I want to develop a profile for each and also group similar users using clustering. Question: When developing a profile for each user, ...
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75 views

Weighted median of a portfolio

I need to calculate weighted median return for a portfolio (using MATLAB). There is information available online: MATLAB Central/rates&weights and Excel/note 4+4+4+7+7/5 logic How would you ...
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14 views

can one approximate median of non central t- location scale distribution

Generally one can approximate the median to be the non central parameter. I want full proof of the same. can you please give me any journal paper link, in which this has been proved.
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33 views

Calculation of median: Why are means of ranks not used for it?

in order to calculate the median, I have to sort the data in a ascending/descending order. Each value gets a rank so that I can (for uneven samples) look up the value that rank X = (n + 1)/2 has, ...
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68 views

Interpreting contradicting results T-Test vs. Mann-Whitney test (2 independent samples)

I want to test if two indepent experimental groups are sign. different in terms of one outcome variable, but face the following questions: Basic setup 2 groups with 200 observations each Outcome ...
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320 views

What is the median of the school grades A A B B ?

If the sample was $S_1=\{1,2,3,4\} \subset \mathbb R $ the median is 2.5 because 50% of the sample is $>=$ 2.5 and 50% of the sample is $<=$ 2.5. The median obviously does not need to be ...
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32 views

What is the median of the Dirichlet Distribution?

The Dirichlet is a multivariate generalisation of the Beta distribution, and Wikipedia states that the median of the Beta distribution is the inverse of the incomplete Beta function evaluated at ...
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56 views

CSV file with several values, get median in groups of ten [closed]

I have a csv file with 4000 lines and 270 columns. So I want to read each column and take the median of groups of 10 elements. How do I do this in Python on a fast way, taking into account the number ...
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9k views

Percentile vs quantile vs quartile

What is the difference between the three terms below? percentile quantile quartile
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302 views

Estimating median survival times from Kaplan-Meier plot inspection

I've gone through the various questions relating to Kaplan-Meier plots and survival estimates, but I haven't really been able to find anything to help with this specific scenario. Sometimes, when ...
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Alerting framework for incoming traffic using mean or standard deviation

Currently I put hourly traffic (total number of input requests) of my website in a MySQL table. I keep data for the last 90 days. I want to check every hour, lets say 6th hour, that whether the ...
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56 views

Categorizing a continuous predictor?

If you had to split a continuous (independent) variable ranging from 0 to 9 and reflecting the number of x (e.g. number of cigarettes smoked), would you rather do: Median split (but then also ...
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108 views

Median-computation (“grouped median”). Problem with gmedian-computation in SPSS

In my basic-statistics course I wanted to delve deeper into the problem of the (grouped) median-computation and did some computations using SPSS. The protocol seems to indicate either a different ...
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164 views

How to compare the distributions of two variables

The attached figure plots the distributions of two variables. I want to demonstrate statistically how closely the the two distributions match each other. What is the best way of doing this?
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51 views

How to quantify the difference of each value with respect to the median of a list of values

I have a list of 7 numbers in the range [0-1]. I have a median of all of them. I would like to quantify how much different each number is from the median. Probably it is a stupid question but how can ...
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63 views

Representative transaction KPIs - what method to chose (average, median…) / how?

In my dataset i have about 30k of transactional data. For analysis, I want to show the end user some important KPIs: Average of transactions with loyalty cards Average turnover of these transactions ...
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443 views

Is the median a “metric” or a “topological” property?

I apologize for the slight abuse of terminology; I hope it will become clear what I mean below. Consider a random variable $X$. Both the mean and the median can be characterized by an optimality ...