Have you read this?

Vic Barnett (1994) Outliers in sample surveys, Journal of Applied Statistics, 21:5, 373-381, DOI: 10.1080/757584014

Joseph C. Kush No I haven't yet. But unfortunedly I have no access to this one.

There are few tests for outliers. See the article 'Algorithm 974: The OutlierLib - A MATLAB library for outliers' detection' , ACM Transactions on Mathematical Software, 43(4):38, March 2017 (https://www.researchgate.net/publication/315519154_Algorithm_974_The_OutlierLib_-_A_MATLAB_library_for_outliers%27_detection).

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I refer to the link

https://www.surveygizmo.com/resources/blog/identifying-statistical-outliers-in-your-survey-data/

https://www.researchgate.net/search.Search.html?type=publication&query=How%20to%20deal%20with%20outliers

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In attachment :-

Dealing with Outliers in Survey Data

• December 2009
• Handbook of Statistics 29:247-279
• DOI:10.1016/S0169-7161(08)00011-4

Vic Barnett is a leading expert in Outlier research. You can get his paper that was recommended by Dr Kush above at:

Article Outliers in sample surveys

D. Booth

Tobias Rosinski If you are interested in computing average then you may use

http://www.naturalspublishing.com/show.asp?JorID=29&pgid=0

Moreover, I send you the paper on Outliers in sample surveys. Please check the attached file.

Thank you very much for support!

See the solution in applied multivariate analysis by johnson and wichern.....