Hi Statalisters,

I am new to Stata and have some questions about data management.

In the following sample, I have a data with three variables, CONM, DATE, and SALES. What I want to do is to build a logic that can detect the validity of the observations. That is, for each company in each year, its smallest sales must take up at least 10% of the total sales.
For example, for company 2U INC, in 2012, its total sales is 43.6+8.4=52.0, if the smallest sales 8.4 takes up at least 10% of the total sales, 52.0, we can say the result is "valid" (can be denote as dummy variable 1 or anything else). For the same company 2U INC, in 2015, its total sales is 65.2+23.8+17.6=106.6, and the smallest sales 17.6 still takes up more than 10% of the total sales, the result is "valid".
The detect procedure should be categorized based on both company and date.

Can Stata work this logic out properly? Is there any good suggestions about this issue?

Advanced big thanks here.


CONM DATE SALES
2U INC 12/31/2012 43.586
2U INC 12/31/2012 8.382
2U INC 12/31/2013 13.3
2U INC 12/31/2013 57.358
2U INC 12/31/2014 60.631
2U INC 12/31/2014 15.433
2U INC 12/31/2015 65.2
2U INC 12/31/2015 23.8
2U INC 12/31/2015 17.6
2U INC 12/31/2016 22.1
2U INC 12/31/2016 36.7
2U INC 12/31/2016 71
2U INC 12/31/2017 28.3
2U INC 12/31/2017 77.6
2U INC 12/31/2017 48.2
2U INC 12/31/2018 54.2
2U INC 12/31/2018 42.7
2U INC 12/31/2018 86.9
360 SECURITY TECHNOLOGY INC 12/31/2010 12.167
4LICENSING CORP 12/31/2010 5.646
4LICENSING CORP 12/31/2011 5.556
4LICENSING CORP 12/31/2012 2.494
4LICENSING CORP 12/31/2012 0.333
6D GLOBAL TECHNOLOGIES 12/31/2010 6.91
6D GLOBAL TECHNOLOGIES 12/31/2010 6.687
6D GLOBAL TECHNOLOGIES 12/31/2010 3.344
6D GLOBAL TECHNOLOGIES 12/31/2010 2.675
6D GLOBAL TECHNOLOGIES 12/31/2011 3.369
6D GLOBAL TECHNOLOGIES 12/31/2011 2.305
6D GLOBAL TECHNOLOGIES 12/31/2011 3.724
6D GLOBAL TECHNOLOGIES 12/31/2011 3.724
6D GLOBAL TECHNOLOGIES 12/31/2012 2.073
6D GLOBAL TECHNOLOGIES 12/31/2013 2.122
6D GLOBAL TECHNOLOGIES 12/31/2013 1.061
6D GLOBAL TECHNOLOGIES 12/31/2013 0.299
6D GLOBAL TECHNOLOGIES 12/31/2013 1.061