# Questions tagged [winsorizing]

Winsorizing is a kind of data transformation used in robust/resistant statistics. Extreme values in the sample is replaced by some chosen data quantile(s). See https://en.wikipedia.org/wiki/Winsorizing

51 questions
Filter by
Sorted by
Tagged with
28k views

### Replacing outliers with mean

This question was asked by my friend who is not internet savvy. I've no statistics background and I've been searching around internet for this question. The question is : is it possible to replace ...
22k views

### What are the relative merits of Winsorizing vs. Trimming data?

Winsorizing data means to replace the extreme values of a data set with a certain percentile value from each end, while Trimming or Truncating involves removing those extreme values. I always see ...
61k views

### Should the mean be used when data are skewed?

Often introductory applied statistics texts distinguish the mean from the median (often in the the context of descriptive statistics and motivating the summarization of central tendency using the mean,...
9k views

### Which robust correlation methods are actually used?

I plan to do a simulation study where I compare the performance of several robust correlation techniques with different distributions (skewed, with outliers, etc.). With robust, I mean the ideal case ...
22k views

### How to correct outliers once detected for time series data forecasting?

I'm trying to find a way of correcting outliers once I find/detect them in time series data. Some methods, like nnetar in R, give some errors for time series with big/large outliers. I already managed ...
3k views

### Alternatives to using Coefficient of Variation to summarize a set of parameter distributions?

Background I have a model with 17 parameters, and I currently use the coefficient of variation ($\text{CV}=\sigma/\mu$) to summarize the prior and posterior distributions of each parameter. All of ...
1k views

### Downweight outliers in mean

I have a bunch of points $x_i$ and would like to calculate a kind of weighted mean that deemphasizes outliers. My first idea was to weight each point by $1/ (x_i - \mu)^2$. However, the problem is ...
2k views

### Does Pearson correlation require removal of bivariate or univariate outliers?

Does the Pearson's correlation estimator require no bivariate outliers, or no outliers in each of two individual vectors of data? The answer will impact on how I winsorize outliers before calculating ...
2k views

### Outlier detection for generic time series

In this case, "generic" being the entire gauntlet of macroeconomic time-series that private and government statistical offices put out. Some background - I recently started working at a data provider ...
4k views

### Extreme values in the data

I have a very general statistical question. If a variable has some extreme values, then for the purpose of statistical inferences for example OLS regression, is it better to detect these extreme ...
450 views

### How to average quantized and truncated data?

So I have data that has been quantized by an analogue to digital converter. (continuous data has been turned into discrete data and the values range from 0 to the saturation value , which is 127 in ...
550 views

### Why are Winsorized random variables independent?

While studying trimmed mean I understood that if I have some random variables $X_1, X_2, .., X_n$ by ordering them and trimming, the variables are no longer independent. However it is said that "by ...
335 views

### In a “bursty” dataset, how do you filter for the few important values that make up the bulk of the information?

Note sure if there is an existing stats concept for this but I have a dataset that consists of mostly small data points with a few large ones. e.g. 1 2 1 3 1 2 87 3 2 1 1 1 1 3 1 2 1 1 1 99 How can ...
785 views

### Dealing with outliers when comparing variances with Bartlett's test

I have four different groups (with unequal sample sizes of 100 to 120) and want to test if the variance differs. For ANOVAs I used the winsorized mean to get a more robust estimate and I am wondering ...
2k views

### How to describe the differences in skewed data with same median but statistically different distribution?

I am comparing length of stay after laparoscopic and open appendectomy in over 160000 patients. LOS is typically a skewed variable so I use the median and interquartile range and ranksum test to ...
2k views

### use and misuse of Winsorization

I am doing research on Winsorization (and trimming), which has been broadly applied in many fields, but I think many researchers didn't do it in a "rigorous" way. Or maybe even worse, they misuse it. ...
864 views

### Linear regression with violated assumptions

I am trying to find out the determinants of cognitive function. The outcome variable is the miniāmental state examination which is a 30 point questionnaire response that has score values from 0 to 30(...
2k views

### Removing outliers from asymmetric data

I have a data set that includes the number of visits to a website. Here are some descriptive statistics for my data Median: 4 Mean: 14.1352 SD: 121.8119 Clearly, there are some huge values (...
506 views

### How to best estimate the time remaining for a variable-length questionnaire?

The greatest gain of the statistics classes in both school and university seems to be that I now have an inkling of which QA site to use for this question. :) I'm a programmer and I'm making a ...
79 views

### Limiting the range of numbers

Suppose that I have the following data set: {0.1, 0.2, 0.5, -0.1, 0.5, 1.1, 0.8} I would like to limit the range of these data to be within the range of [0,1]. ...
924 views

### Treating outliers for time series forecasting in Python

What is the best way to treat outliers in a time series forecasting model? In particular, for product demand modeling? Based on what I've read so far, the following methods can be applied: ...
2k views

### Measure of closeness

Given a list of numbers, is it possible to find out (or in other words, is there a statistical measure to tells the) the closeness of the numbers (do note that i am not talking about correlation - ...
2k views

### Robust standardization of data

I have some data where I want to determine whether the shape of the probability distribution has changed compared to 10 years ago. One example is that I have for various automobiles multiple measures ...
503 views

### Does the Hodges-Lehmann estimator perform better than trimmed/winsorized means?

I've been reading about the HL estimator, and a question came to mind. I could fairly easily create a mean-estimator where I trim or clip 29% of the data on either side and have a statistic with a ...
593 views

### Removing outliers and calculating a “lowest” attainable price from a pre-determined/fixed time series of prices

Just a foreword, I'm not a mathematician or otherwise statistically skilled. I know my way around calculating standard deviations, but it's all self taught. I'm a programmer with limited stats ...
229 views

### Multilevel modeling for limited dependent variable

I am doing the research, using Multilevel modeling, with limited dependent variable number of days- it is limited downward (0) and upward (30). Is it necessary to use Multilevel logit model? Or is it ...
417 views

### Ensemble time series prediction from two separate models

I have two different forecasts that are produced by ARMA models using two different data samples. The difference between the two data sets is their size: one used data from 2013-2014 and another used ...
742 views

### Scale independent forecast error metric that works with changing signs

I am trying to analyze a quite large (~25,000 rows) dataset of cash flow forecasts. Receipts and expenses are aggregated, thus I may end up with the following data: ...
428 views

### Combining similarity scores

I have a list of m x n similarity score matrix, something like ...
161 views

### Does pre winsorising of a variable help for a logistic regression?

I am wondering if winsorising makes a difference in a logistic regression. In a situation where I am looking at the individual contribution, looking at their individual discriminatory power (...
110 views

### Optimizing Robust Statistics

A robust paired t-test is a better choice for skewed distributions than the conventional paired t-test (e.g Fradrette, Keselman, Lix, & Wilcox, 2003). One version of the robust test uses a trimmed ...
237 views

### Transformation and/or Winsorizing?

I want to compare two group of 24 and 28 people with t-test on type of activity (5 different's types of activity and a total), later one the same value will be use in regression logistic. If you ...
179 views

### Robust Estimators - Winsorized Variance degree of freedom (df)

this is my first question on this site. So, I'm currently working on my final year thesis, and it was on Robust statistics. In my work, I will use Trimmed Mean, Winsorized Mean and Winsorized ...
455 views

### Greater than 30% outliers in small dataset - what to do? Standard test? Test with outliers removed? Robust statistics?

I have a small-sample dataset representing observations from a longitudinal study. My principal interest is in 'change scores' across three parameters (A, B, C). This requires simple paired t-tests. ...
725 views

### What is the difference between GAS ( Generalized Autoregressive Score) model and a GARCH?

I am trying to analyze some data about Brent Oil volatility. So far I have managed to fit a GARCH(1,1) model and an EGARCH. However, someone has recommended to use a GAS model, Generalized ...
806 views

### How do I calculate the ranking of some galleries based on the rankings of the artists represented by them?

The mean is not good in this case, because there are galleries that have an artist with a high rank and several other artists with way lower ranks. I'm thinking about doing a weighted mean, but I don'...
640 views

### Measure of central tendency for an ex-gaussian distribution

I know there won't be a clear answer to that question but I'm really curious to know your opinion on that matter. I deal with reaction times, and finding a good measure of central tendency is ...
42 views

### Winsorizing propensity scores

Is it kosher? Inverse propensity weights (IPW) has been shown to perform poorly when selection probabilities are small (Kang and Schafer, 2007). Are there any standard solutions to this issue?
1k views

### Treatment of outliers in financial data

I have a data set with financial panel data from 150 companies. I want to analyse the data using linear repeated measures ANOVA and OLS Regression (so far). For this, I want to use the absolute values ...
9 views

### Name for the opposite of Winsorizing?

For some regressions we find it useful to focus on extreme values, and so we discard middling dependent values (which we might call "noise") from data in order to find relationships that hold at data ...
137 views

### Winsorization when we run regressions by size group

I have a sample that consists of large, medium, and small firms and i want to run a separate regression for each size group. When I winsorize a variable should I do it for the whole sample (i.e. ...
81 views

### Winsorizing, just the outlier or all the value?

I have an outlier in my data set. I want to use the winsorizing quartile (to change the outlier to the 5th% and/or 95th%). Looking at the quartiles, sometimes I have more values than just my ...
2k views

### Winsorizing data

I am currently working on my bachelor thesis in finance and I faced some problems regarding my dataset. I wanted to analyze the effect of leverage on the performance of companies and as many ...
340 views

### Is Winsorization performed on test data as well?

I know what is Winsorization and why is it applied. My understanding was that it is applied only on the train data to reduce the effect of outliers. But! Recently I came across a kernel where Min, ...
34 views

### winsoring forecasting dataset

I have performed a logistic regression to estimate the default probability of a dataset of firms based on some basic balance-sheet ratios. I have winsorized all the ratios at the 1st and 99th ...
108 views

### How to evaluate a curve considering outliers?

I have data on runners who run marathons; for each runner I have their final times on a number of races. I would like to predict how fast they are running considering outliers i.e. he's running ...
208 views

### How to choose cut off for winsorization/ flooring- capping? What is the impact of variable distribution on the decision

To perform logistic regression I wish to winsorize outliers in independent/ explanatory variables by flooring and capping independent variables. Can you suggest how I should choose cut-off for ...
222 views

### Winsorizing data in small sample

I have a relatively small sample of panel data (quarterly data for 68 firms over 7 years). My dependent variable is positively skewed. In order to limit the influence of observations with large values,...