Collusive oligopoly is a form of market in which few firms form a mutual agreement to avoid competition. They form a cartel and fix the output quotas and the market price. Leading firm in the market is accepted by the cartel as a price leader. All the firms in the cartel accept the price as fixed by the price leader.

Non-collusive oligopoly is a form of market in which few firms. Each firm has its price and output policy is independent of the rival firms in the market. The entire firms enable to increase its market share through competition in the market.

An index number is not an absolute measure, it measures the percentage change in a variable over time. It does so by comparing the value of a variable at present to its value at a base year. Index number gives a quantitative foundation to qualitative statements like prices are falling or rising

econdary data are those which have already been collected and analyzed by someone else. There are two major sources of Secondary data. They are:

a.     Published Sources: The sources of published data are as below:

i.     Official publications of Central and local governments.

For example: CBS, NRB, different Ministries, etc.

ii.    Official publications of semi government statistical organization. For example: Tribhuvan University, Nepal Bank Ltd., NIDC, Nepal Telecom Ltd, NEA etc.

iii.   Official publication of foreign government or international bodies like the UNO, World Bank, ADB, WTO, UNESCO, etc.

iv.   Reports and publications of Trade union, Chamber of Commerce, Commercial Banks, Co-operatives, Stock Exchange etc.

v.    Report submitted to economists, re-search scholars, universities and various educational and research institutions.

vi.   Reports of various committees and commissions appointed by government.

vii.  Newspaper and Periodicals.

Some of them may be continuous or regular and others are periodical and irregular.

b.     Unpublished Sources: The statistical data needn’t always be published. There are various sources of unpublished statistical material such as the records maintained by private firms, business enterprises, scholars, research workers, etc. They may not like to release their data to any outside agency.

Resources such as land, labour and capital are limited in relation to their demand and economy cannot not produce all that people required to satisfy themselves. This is why the existence of economic problems in an economy. Scarcity is universal which is applicable to all individuals, institutions and economy as a whole. If there is abundant or sufficient resources then there will not be any problem in an economy. Hence, scarcity leads to economic problem. 

According to the Law of Diminishing Marginal Utility, marginal utility of a good diminishes as an individual consumes more units of a good. In other words, as a consumer takes more units of a good, the extra utility or satisfaction that he derives from an extra unit of the good goes on falling.