Why is it easier to quantify paid work done outside the home over unpaid housework and childcare?

It is easier to quantify paid work done outside the home over unpaid housework and childcare because traditional means of tracking economic activity, such as the gross domestic product (GDP) can be used. Housework on the other hand is not easily measurable because the traditional means of tracking economic activity do not take account of non-exchange, non-market household activity.