How to remove bad data (outliers) from a plot?

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asskicker
asskicker on 18 Nov 2014
Answered: Steven Lord on 15 Jun 2018
I plot my data and a line of best fit together. I realized there are a few obvious bad data (outliers) in my plot and I need to remove them.
How do I do that?
Thanks!
  1 Comment
STEPHEN ROSS
STEPHEN ROSS on 15 Jun 2018
For small data sets less than 60, use Peirce's Criterion for an excellent statistical method: "https://www.researchgate.net/publication/267241891_Peirce%27s_criterion_for_the_elimination_of_suspect_experimental_data"

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Answers (3)

Image Analyst
Image Analyst on 18 Nov 2014
See Brett's File Exchange submission: http://www.mathworks.com/matlabcentral/fileexchange/3961

Star Strider
Star Strider on 18 Nov 2014
The most acceptable way is to set confidence limits based on a particular probability and eliminate those data that are outside them. (If you have a large data set, you would expect some valid data to be outside the expected confidence limits.) Various Statistics Toolbox functions such as regress for linear regression and nlpredci for nonlinear regression can calculate these confidence limits for you.

Steven Lord
Steven Lord on 15 Jun 2018
If you're using release R2017a or later, use the isoutlier and/or filloutliers functions in the "Missing Data and Outliers" section on this documentation page.

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