Families and households change their composition over time as individuals arrive (e.g. via birth of a child or marriage) or depart (e.g. via a child becoming non-dependent or leaving home, death or divorce). And these types of change are common (see e.g. Jenkins, 2000). Thus one can only follow individuals over time, though of course one can characterise individuals in terms of their family’s characteristics including receipt status at a given point in time.