A small proportion of the difference between the hours spent by males and females in different activities is due to the fact that there are more women in the population. This means approximately 7 billion more hours in the year 2000, to be divided between females' household production, paid employment, other activities and sleep. This is if only the hours spent in primary activities are counted - a total of 464 billion hours for males and females.

Females spent 27 per cent of their total hours – including primary and secondary activities and passive care - on household production and 7 per cent in paid work, while males spent 20 per cent of their total hours on household production and 12 per cent in paid work. If we look only at primary activities, both males and females spent approximately 27 per cent of their time in household production and paid employment, with males spending 13 per cent of their time on household production, compared with 19 per cent of females’ time.  These gender differences are not as stark as those suggested by other research, because of the activities we have included in our calculations.