When a country collects data for calculating the Gini index, do they usually neglect single household? OECD data for South Korea is based on the numbers provided by Statistics Korea, which does not count single household family income data in their statistics. I am just curious that neglecting single household is a general or traditional statistical method for getting sound Gini index so other countries use same way Or, it just happens in South Korea. Recently, The number of single households are growing fast, and usually their incomes are lower, so neglecting single household data leads lower Gini index, which means lower inequality. Do the other countries use the similar criterion for gathering data for Gini index? If the countries use different criterion , where could I find that?
I am not sure this is currently correct as http://www.oecd.org/els/soc/OECDIncomeDistributionDataReview-Korea.pdf says: 


  Income distribution and poverty indicators for Korea are also available from:
  
  
  The  same  combination  of  Household  Income  &amp;  Expenditure  survey  combined  with  Farm household economy survey from previous years, using different coverage of population
  
  Since 2006: all households (same series as OECD reference series)
  
  
  Since 2003: only for 2 and more non-farm household
  
  
  Since 1990: only for urban salary and wage worker, 2 and more household
  
  


which I intepret as saying that all households have been counted since 2006, while only households with 2+ people were counted from 1990 to 2005