(i) PPI - Purchasing Power Parity
(ii) HD - Human Development Index.

(i) Human resource is necessary for the progress of any country.
(ii) It refers to the collective abilities of people which can be utilised in the production sector.
(iii) It is invested with good education and health.
(iv) Therefore investment in education and health can result in a high rate of returns in the future.

(i) The Net National Product (NNP) is considered as a true measure of national output. It is also known as national income.
(ii) A rise in per capita income means an increase in aggregate real output. Hence, this is a better indicator than national income for measuring development.
(iii) For measuring a country's development, its income is considered to be one of the most important factors. Countries with higher income are considered to be more developed than those with lesser income.
(iv) So, income itself is considered to be one of the indicators of economic development.

The major indicators to measure the level of economic development are
1. Net National Product (NNP),
2. Per Capita Income (PCI),
3. Purchasing Power Parity (PPP),
3. Human Development Index (HDI).

(i) Development refers to the progress of a particular field or a particular person.
(ii) The economic progress of a country is known as economic development.
(iii) Development refers to the improvement in quality of life such as higher income, better education, better health and nutrition less poverty and more equal opportunity.