15 questions linked to/from Outlier Detection on skewed Distributions
9k views

### Z Score for Non Normal Data [duplicate]

I am looking for some direction to see if there is an equivalent metric to a z score that could be used to quickly identify individual values in a non-normal distribution that are not likely to occur (...
79 views

### Method to determine outliers with a skewed dataset [duplicate]

How can we find outliers in a dataset with a (highly) skewed distribution? With a normal distribution, is it well documented to use 2 x Standard Deviation or the upper boundary of the box plot (1.5 x ...
77 views

### Detecting outliers in time-series if I don't have a “normal” dataset [duplicate]

I have been trying to detect anomalies in my time-series dataset. What I am trying to accomplish is the following: I have a multivariate dataset, where two columns are of special interest. One tells ...
48 views

### For univariate outlier analysis should I use z score if my data is skewed? [duplicate]

If my data is skewed, does it mean that my data does not follow a normal distribution? How do we define various distributions? What type of outlier analysis do I perform for the different type of ...
10k views

### Is there a boxplot variant for Poisson distributed data?

I'd like to know if there is a boxplot variant adapted to Poisson distributed data (or possibly other distributions)? With a Gaussian distribution, whiskers placed at L = Q1 - 1.5 IQR and U = Q3 + 1....
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### Can we use leave one out mean and standard deviation to reveal the outliers?

Suppose I have normally distributed data. For each element of the data I want to check how many SDs it is away from the mean. There might be an outlier in the data (likely only one, but might be also ...
9k views

### Detecting outliers in count data

I have what I naively thought to be a fairly straight forward problem that involves outlier detection for many different sets of count data. Specifically, I want to determine if one or more values in ...
12k views

### Why does Tableau's Box/Whisker plot show outliers automatically and how can I get rid of it?

I have a data set shown as box-whisker graphs after disaggregating. See below. I am wondering why Tableau (the product I am using) automatically plots a whole bunch of values outside the box-whisker. ...
17k views

### how to determine skewness from histogram with outliers?

I have the following histogram created in Minitab. I am wondering whether this histogram is actually positively skewed, negatively skewed, or symmetric. By observing the graph itself, it seems that ...
7k views

### When finding outliers from the Interquartile range why I have to multiply by 1.5?

I was looking at the outlier detection formula which uses the IQR and I wonder why it should be multiplied by 1.5? Can the constant be increased i.e 3 or 6 to be more "acid" if so under what criteria?
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### Using percentiles and inter-quartile-range for outlier detection in skewed data

I am analyzing the age of a certain group of people and I want to use percentiles and inter-quartile-range in the data to flag possible outliers. I am getting Q1 - 25th percentile, Q3 - 75th ...
5k views

### threshold based on mean and standard deviation

I have a time series of 70000 data points. I want to separate samples of this time series which have very large values as compared to the time series. How can i threshold sample to separate. What i ...
137 views

### In R, how to detect possible outliers in right skewed data assuming Poisson distribution?

I am attempting to identify possible outliers in data which is skewed to the right and I assume it is Poisson distributed. I am a novice in all things statistics, and the following may be utterly ...