It has the advantage that, assuming that the dollar a day absolute line is an adequate measure of survival, we do not rely on information from other countries to set a given country's poverty line. This cannot be said of proposals to define global poverty schedules since, in practice, because the parameters of hybrid lines such as Ravallion and Chen's (2011) are set to fit the observed official poverty lines, they depend on the behaviour of governments in setting the poverty line. Calibrating international poverty lines to data on national poverty lines does provide important clues, not easily available in another way.