1. Personal disposable income refers to disposable income of only the individuals and households in the country. National disposable income refers to disposable income of the country as a whole.
2. Personal disposable income is estimated as the sum total of household consumption and household saving. It is the income remaining with the individuals and the households after payment of all the taxes levied against their income and their property by the government.

National disposable income is estimated as the sum total of net domestic income at factor cost, net indirect taxes, net factor income from abroad and net current transfers from the rest of the world.

Generally, publication occurs on the date on which copies of the work are first made available to the public. Unpublished works are those which have not been distributed in any manner.

A perfect competition is the market situation where there are a large number of sellers competing to sell a homogenous product at a price fixed by the market. In such a case, a uniform price prevails in the market. This is decided by the industry itself (market forces of demand and supply).
Features of Perfect Competition

An essential aspect of perfect competition is the absence of any monopolistic element. These are the three essential features of perfect competition:

1. The number of buyers and sellers in the market is very large. These buyers and sellers compete among themselves. Due to the large number, no buyer or seller influences the demand or supply in the market.
2. The commodity sold or bought is homogeneous. In other words, goods produced by different firms are identical in nature.
3. Firms can enter or exit the market freely.

Perfect competition is a form of the market where there is a large number of buyers and sellers of a commodity. Homogeneous product is  sold and its price is determined by the forces of market supply and market demand. An individual buyer or seller has no control over the price.  

Features of perfect competition:

1.  Large number of small buyers and sellers of a commodity: under perfect competition there is a large number of buyers and sellers. The number of buyers are so large that the demand of an individual buyer is only a small fraction of market demand for a commodity. Likewise the number of sellers are so large that the supply of an individual seller is only a fraction of the market supply.
2. Homogeneous product: The product under perfect competition is homogeneous. A product is said to be homogeneous when each unit of it identical in size, shape, color and weight. So that, the buyer do not find any difference in product as sold by different firms in the market.
3. Freedom of entry and exit: Under perfect competition a new firm is free to enter the industry and an existing firm is free to leave it.

There are following limitations of statistics :
Sometimes, when data are not properly collected 1 then there is likelihood to draw wrong conclusions.
Therefore, it is necessary to know the limitations of statistics.
(i) Statistics does not study about individuals : Statistics are expressed in facts. It does not study individuals. For example, there are five students in a class. Statistics only tells the average marks obtained in class not how many marks are obtained by every student in the class.
(ii) It does not study the qualitative aspect of problem : The most important condition of statistical study is that subject of investigation and inquiry should be capable of being qualitatively measured. For example, honesty, poverty, etc.
(iii) Statistics can be misused: The result obtained can be manipulated accordingly to one’s own interest and such manipulated results can mislead the community.
(iv) Statistical results lack mathematical accuracy: The results drawn from statistical analysis are normally in approximates. As the satistical analysis is based on observation of mass data, number of inaccuracies may be present and it is difficult to rectify them.
(v) Uniformity and homogeneity of data : It is essential that data must have the quality of uniformity and homogeneity. Heterogeneous data are not comparable. For example, it would be meaningless to compare the heights of men with heights of trees because these figures are of heterogeneous character.

Higher indifference curve represents a higher level of satisfaction because higher IC means a bundle consisting more of both the goods or same quantity of one good n more quantity of the other good . It is based on the assumption that the consumer has monotonic preference , ie , more consumption gives him more satisfaction .

Statistics refers to the aggregates or averages that relate to an enquiry or some relationship. Such aggregates facilitate the presentation of data in a simplified manner. Besides presentation, statistics also enable a reader to make comparison among two or more variables. On the contrary to this, statistics also involve some limitations which often lead to the situation of distrust on statistics and its methods. Such limitations evoked ‘Mark Twain’ of U.S. to introduce a phrase called ‘Lies, Damned lies and Statistics’. This phrase was introduced to highlight the shortcomings (limitations) associated with statistics.
The following are the limitations which resulted in mark of statistics as a lie:

• The users of the statistics usually tend to manipulate the data to support their already drawn conclusions, which leads to the situation of distrust and the process of data manipulation.
• The statistical figures are made so convincing that people feel bound to trust on such figures.
• The readers are often mislead by the way of presentation of data (even if correct). For example, if per capita income of the country increases then it represents the readers to be convinced that the income of all the people in the economy increases. However, if the distribution of income in the economy is inequitable then the income of only a section increases while the other section of population lives in poverty.