Merits:

1. Economical: It is economical, because we have not to collect all data. Instead of getting data from 5000 farmers, we get it from 50-100 only.

2. Less Time Consuming:As no of units is only a fraction of the total universe, time consumed is also a fraction of total time. Number of units is considerably small, hence the time.

3. Reliable: If sample is taken judiciously, the results are very reliable and accurate.
 

Demerits:

1. Absence of Being Representative: Methods, such as purposive sampling may not provide a sample, that is representative.

2. Wrong Conclusion: If the sample is not representative, the results will not be correct. These will lead to the wrong conclusions.
 

3. Small Universe: Sometimes universe is so small that proper samples cannot be taken not of it. Number of units are so less.

Census arrangement applies to the whole inventory of a universe. creation may be an area, an assortment of individuals or a particular location through which we accumulate the data.

The advantages of the census method are:

1. It is trustworthy and reputable.
2. It can give the correct estimation of some produce and yield, the population of particular age groups, their associations by ***, institutional knowledge, etc.

Disadvantages of the census method are

1. Census can require a lot of time to provide reports and also huge capital
2. Every segment or article of the population has an identical probability of being chosen.

The word statistics is used both in plural as well as in singular sense. In plural sense, statistics means numeric facts which can be used to draw conclusions and in singular sense, it means the statistical methods with the help of which statistical information is used to treat and draw conclusions from them.
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.

The word statistics is used both in plural as well as in singular sense. In plural sense, statistics means numeric facts which can be used to draw conclusions and in singular sense, it means the statistical methods with the help of which statistical information is used to treat and draw conclusions from them.
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.

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.

Stages of statistical study are the following: 

- Collection of Data 

- Organizing Data 

- Presentation of Data 

- Analysis of Data 

- Interpretation of Data  

And for the statistical tools graphs and tables are well-known methods.

It is true that statistical methods are no substitutes for common sense and that one must not believe statistical data blindly as they can be misterpreted or misused.

Statistical data may have errors made by the investigator while collecting or analysing data.

For example, you may find relationships such as; more the number of schools in an area, more will be the number of educated children. While this may be proved true statistically but this doesnot match with common sense. 

Thus it is important that one uses his/her common sense while working with statistical data.

“The term ‘market’ is not any particular place in which things are bought and sold But the whole of any region where buyers and sellers are in such free intercourse with one another that the price of the same goods tend to equality easily and quickly.”

Individual Series ;-
When the raw data is presented individually in the form of a series, it is called an individual series. In simple words, individual series is the arrangement of raw data individually. It gives numeric values for a specific situation. In an individual series items are shown singly.
For example, following are the marks of secured by the students in a class out of 100.
56, 77, 88, 49, 60, 92, 70, 81, 69, 51,
As we can see, in the above data, it is not clear that how many students got 56 marks or how many got 77 and so on.
Discrete Series :-
On the other hand, discrete gives data for each specific value of variable. The important thing in the discrete series is that, the variable involved in the series has integer values. Data are presented in a manner that exact measurement of items are clearly shown. 
For example, Given below is a table that shows the wages earned by 30 workers. 
Wages                  No. of Workers (Frequency)
 2500                                 7  
 3000                                 9
 4000                                 5
 4500                                 6    
 5000                                 3
From the above table, it is very clear that 7 workers are getting wages Rs. 2500, 9 workers are getting Rs. 3000 and so on.

In Indirect Oral Investigation, data is collected through indirect sources. Persons who are likely to have information about the problems, are interrogated and on the basis of their answers, factual data have to be compiled. Most of the commissions of enquiry appointed by government collect primary data by this method. The accuracy of the method depends largely upon the type of persons interviewed and hence these persons have to be selected very carefully.
Merits of Indirect Oral Investigation:
(i) It is economical in terms of time, cost and manpower.
(ii) Confidential information can be collected.
(iii) Information is likely to be unbiased and reliable.
(iv) This method is relatively simple to under-stand.
Demerits of Indirect Oral Investigation.
(i) The degree of accuracy of information is less.
(ii) This method leads to doubtful, conclusion due to ignorance and carelessness of the witness.

Law of diminishing marginal product or productivity is an economic theory. It proclaims that while increasing one input and maintaining other inputs constant initially helps in increasing the output, a further increase in the input will have a restricted effect and will ultimately have nil consequence or a pessimistic effect on the output.

The Law of Diminishing Marginal Productivity helps in understanding why increased manufacturing isn’t always the best way to increase profitability.

A characteristic which is capable of being measured and changes its value over time is called a variable.

'Statistics' is also a singular word denoting a field of knowledge. ... A 'statistic' is a numerical fact, or a piece of numerical information or data, and collections of such things are called 'statistics' plural. So statistics (plural) are part of the concern of statistics.   In its plural sense, statistics refers to information in terms of numbers or numerical data such as population statistics, employment statistics etc.

Desire refers to the wish a person has.

Want is a strong feeling of possessing some things.

Demand refers to the desire to have a commodity backed by willingness and ability to purchase that commodity at given price during a period of time.

Economics agents are those who take Economic decisions. In microeconomics there are Individual economic agents and at macro level there are institutional Economic agents who take Economic decisions.

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.

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.

Changes in demand include an increase or decrease in demand. Due to the change in the price of related goods, the income of consumers, and the preferences of consumers, etc. the demand for a product or service changes.

So there are two possible changes in demand:

• Increase (shift to the right) in demand
• Decrease (shift to the left) in demand