A report by the World Bank noted the following: "Informal economic activities pose a particular measurement problem in calculating GDP, especially in developing countries, where much economic activity may go unrecorded".
1) What does the World Bank mean by "informal economic activities"?
2) Why would these activities make it harder to measure GDP?
3) Why might they make it harder to evaluate the standard of living in developing countries relative to the standard of living in developed countries such as Australia?