Affordability is "the number of days’ wages required by the lowest-paid unskilled government worker to purchase 7 days’ supply of a medicine to treat an acute condition, and 30 days for a chronic condition, based on standard treatment regimens". Affordability allows to express medicine costs as the ability of an individual's ability to pay for it, which is more relatable for the general public and "serves as an advocacy tool". Cross-country comparisons of affordability are possible. The same methodology can be applied to evaluate medicines availability, compared to a basket of reference countries.