How to tag outliers?

[Krishna Prasad Srinivasan]

Hi, I would like to create a dummy that's equal to 1 if it's an outlier, and 0 if not. I can use -extremes- to display the outliers, but not tag the corresponding values.

* Example generated by -dataex-. To install: ssc install dataex
clear
input double var
 7.000e+08
 2.100e+09
 2.200e+08
 3.500e+08
  75000000
 1.200e+08
 4.000e+08
  40500000
  20000000
 5.000e+08
 2.000e+08
  85000000
 1.250e+09
 2.000e+08
 3.000e+09
 1.500e+09
 4.000e+08
  10000000
 1.240e+09
  75000000
 1.200e+08
 1.100e+08
 3.160e+09
 1.200e+09
 1.000e+09
 2.480e+08
  40000000
 1.500e+08
 8.760e+08
 1.000e+08
 1.100e+09
 1.700e+09
 3.500e+08
 2.000e+08
 1.400e+09
 1.500e+08
 1.400e+09
 4.000e+08
 1.800e+08
 1.250e+08
 6.000e+08
 1.000e+08
 1.500e+08
 4.000e+08
 4.000e+08
 2.400e+09
 3.000e+08
 3.500e+08
  30000000
 6.880e+08
 1.200e+09
1135395000
 1.000e+08
 2.000e+08
 1.600e+09
  60000000
  75000000
 1.150e+08
  60000000
 4.500e+08
   1000000
 6.000e+08
 1.800e+08
 1.120e+09
 2.000e+08
 1.800e+08
 1.000e+09
  24000000
 8.000e+08
 1.800e+09
 8.700e+08
  62000000
 1.200e+09
 3.600e+10
 2.000e+08
  16000000
 3.000e+09
 6.000e+08
 4.500e+08
 4.800e+08
 3.600e+08
 840132000
 2.000e+08
 9.000e+08
 3.000e+08
  90000000
 1.050e+09
   8000000
 5.000e+08
 1.000e+09
 5.100e+08
   6000000
 3.000e+08
 5.000e+08
 1.672e+09
 1.600e+08
 2.000e+08
 2.600e+08
 3.200e+09
 2.400e+08
end

extremes var, n(10)

Any thoughts on how to generate the dummy?

Thanks!

[Nick Cox]

What’s your definition of an outlier?

Your anonymous variable has values from millions to billions, so logarithmic scale would seem to be natural for thinking about its distribution.

[Krishna Prasad Srinivasan]

Just the extreme values listed by -extremes- command.

[Nick Cox]

Sounds familiar, somehow. But extremes (from SSC, as you are asked to explain) is for exploration, not for hard-and-fast stigmatization. What you want is programmable, but I am not volunteering.