Economic measures such as the Gross Domestic Product (GDP) and the Gross National Product (GNP) are used to gauge the growth of an economy. Economic development is all about increasing the wealth in a nation as a whole. Economic development is the promotion of more intensive and more advanced economic activities through such means as education, improved tools and techniques, more available financing, better transportation, and creation of new businesses, (Microsoft Student, 2009a).
Gross Domestic Product (GDP) is the total value of goods and services produced in a country over a year. It is an estimate of market throughput, adding together the value of all final goods and services that are produced and traded for money within a given period of time. Gross Domestic Product (GDP) is calculated by adding up the value of all goods and services that are produced, by adding up the expenditure on goods and services at the time of sale and lastly by adding up the producer incomes from the sale of goods or services. Gross Domestic Product (GDP) measures a country’s economic activities regardless of who owns the productive assets in that country, (Costanza etal, 2009:5). One key difference between the two concepts therefore is the value of production by multinational companies which is sent home from abroad. Another difference between the two measures of economic development is that GDP is a better measure of the state of production in the short term whilst GNP is a better measure when analyzing sources and uses of income on a longer term basis. Even though the two measures are commonly used as measures of economic growth and the standard of living, the Gross National Product (GNP) is a more accurate measure of growth and hence, it is widely used than Gross Domestic Product (GDP), (New World Encyclopedia, 2008).

Gross National Product (GNP) is the total value of final goods and services produced in a year by a country’s residents including profits from capital held abroad. GNP can either be real or nominal and this depends on whether it had been discounted in a foreign currency or at current market prices. Nominal GNP measures the value of output during a given year using the prices prevailing during that year. Over time, the general level of prices tends to rise due to inflation, leading to an increase in nominal GNP even if the volume of goods and services produced is unchanged, (Peet and Hartwick, 2009:6a).

On the other hand, real GNP measures the value of output adjusted for inflation. When economic growth over a number of years is measured, change in real GNP is the figure usually used to express that growth. Dividing the GNP by a country’s population yields the GNP per capita. In general, the higher the per capita production or income, the more developed a country’s people are conventionally said to be, and the higher the annual growth rate per capita, the more rapidly a country is said to be developing, (Peet and Hartwick, 2009b).

In addition, Real GNP measures the value of output in two or more different years by valuing the goods and services produced at the same prices. For example, GNP might be calculated for 2008, 2009, and 2010 using the prices prevailing in 2010 for all of the calculations. This gives a measure of national income which is not distorted by inflation.

The Gross National Product (GNP) per capita “is the dollar value of a country’s final output of goods and services in a year divided by the total population of that country. GNP per capita reflects the average income of a country’s citizens. It shows what part of a county’s GNP each person would have if their GNP were divided equally and the first step towards understanding the country’s economic strength and needs as well as general standard of living enjoyed by the average citizen is knowing the GNP per capita of that country, (Microsoft Student, 2009b)

Furthermore, a country’s GNP tends to be closely linked with other indicators that measure social, economical, and environmental well being of the country and its people. For example, the people who live in countries that have a higher GNP per capita tend to have a longer life expectancy, higher literacy rates, better access to safe water and lower infant mortality rates.
Gross National Product (GNP) is measured by totaling all personal spending, all government spending, and all investment spending by a nations industry both domestically and all over the world. GNP can also be figured by the earnings and cost approach of accounting in which all forms of wages and income such as net interest returns, rent, and indirect business taxes, (Microsoft Student, 2009c)

THE HUMAN DEVELOPMENT APPROACH

The other major approach that is used to measure development is the human development approach which centers mainly on human development through ideal measures that have been put in place. Human development is a process of achieving an optimum level of health and well being. Human development includes physical, biological, mental, emotional, social, educational, economical, and cultural components. For human development to be achieved, the United Nations Development Programme (UNDP) in 1990 published a report which is known as the Human Development Report (HDR). The Human Development Report is an annual milestone publication since 1990 and the focus of this report is the Human Development Index (HDI), (Human Development Index, 2010).

Todaro and Smith (2012:48) define the Human Development Index (HDI) as “an index that measures national socioeconomic development based on combining measures of education, health, and adjusted real income per capita. The Human Development Index attempts to rank all countries on a scale of Zero (0) which is the lowest human development to one (1) which is the highest human development. The focus of the Human Development Index is to measure average achievements in human development in a society.

The Human Development Index is a composite scale that has three dimensions or end products of development namely; longevity, knowledge and the standard of living. Longevity is measured by life expectancy at birth; knowledge is measured by average adult literacy (two-thirds) and gross school enrolment ratio (one-thirds) and lastly, the third end product of development is the standard of living which is measured by real per capita income. The Human Development Index ranks countries in four groups of low human development which ranges from 0.00 to 0.499, medium human development which ranges from 0.50 to 0.799, high human development which ranges from 0.80 to 0.90 and the very high human development which ranges from 0.90 to 1.0, (Ibid).
Longevity simply means how long an individual is expected to live. Longevity is measured by life expectancy and Microsoft Encarta Student (2009) defines life expectancy as the average expected length of life. It is the number of years one is expected to live according to statistics. Life expectancy starts from birth and ends when an individual dies. For an individual to have a long life expectancy, certain elements such as the availability of good health facilities, good nutrition to enhance a person’s physical and mental fitness, access to safe drinking water, a clean environment, and proper shelter at large should be available.

Not only is education a key to success but it is also a product of development in such a way that it enriches one’s mind and makes it easy to understand everyday life. Knowledge is measured by an average of two-thirds of adult literacy and a one-third of gross school enrolment ratio. Adult literacy is the percentage of people aged 15 and above who can, with understanding, both read and writes a short, simple statement on everyday life. The combined gross primary, secondary and tertiary enrolment ratio of the ratios of the number of students enrolled in a given level of education, (Ibid, 2009).
The standard of living is measured by per capita GDP. The Gross Domestic Product GDP per capita is the total value of all goods and services that are produced and provided in a country per annum divided by the population of that country. Per capita income represents the amount of goods and services available to an individual in a country. If at all there is an increase in per capita income, the standard of living is also expected to go up. Per capita income is considered an important aspect of human development because it gives people the freedom to purchase goods of their choice, (Todaro and Smith, 2012).
In relation to the Zambian context, the approach that is more relevant to development is the Human Development approach in the sense that the Economic Development approach specifically the Gross National Product (GNP) has certain shortcomings which disqualifies it in being a better approach to measuring development.

Things like income equality, purchasing power parity and education are not measured by GNP. The Gross Domestic Product per capita just measures the average financial well being. The Human Development Index is a better measure of development because it is possible for some not enough developed countries like Zambia to have a high GNP or GDP per capita because they have precious reserves of minerals like petroleum and copper. The Human Development Index is also a broader measure of development in that it takes into account aspects of a better life such as per capita GNP which is a useful economic indicator of the average standard of living. The Human Development Index refers to the process of widening the process of options of people and giving them opportunities for education, health care, income, and employment, (Why is HDI a better measure of development than GNP, 2014).

CONCLUSION
In as much as the Gross National Product (GNP) measures growth in terms economic development and it is used to measure a countries development in monetary terms, the Human Development Index (HDI) is also used rank countries by level of human development. The Gross Domestic Product can be real or nominal. The Human Development Index is a combined normalized measure of educational attainment, life expectancy, and GDP per capita for countries worldwide and it is this combined measure that makes the HDI a better measure of development relevant to development in the Zambian context because it encompasses things like education, health which GNP does not account for.