The sample is small at around 4 000 households or about 10 000 persons, and it is biased toward the low-income populations (the sample does not cover those who change residential area and new buildings which are often occupied by richer households). The RLMS does not seem to be representative at regional level, not least because of the low response rate and high attrition in major cities. Then again, the questionnaire is quite comprehensive on the income side in terms of wage and non-wage incomes of adults and on expenditure patterns including detailed questions on food consumption in the last seven days and non-food consumption over the last three months (OECD, 2011). The wide divergence in estimates may reflect insufficient screening of high-risk sub-populations. Some of the international variations may result from differences across countries in the practice of registering premature babies.