Chapter 1

Basics of data collection

 

(A) Very Short Questions and Answers

1.  Give two examples of secondary data.

Ans: (a) Data collected from Newspaper

(b) Data collected from Magazines.

2. What is the census method?

Ans: Census method refers to the method where data are collected for each and every unit of the investigation.

3. What do you mean by statistical data?

Ans: By statistical data we mean facts and figures.

4. Define enumerators.

Ans: Enumerators are the persons who collect desired statistical information.

5. Define respondents.

Ans: Respondents are the persons who provide the actual data.

6. Write any two demerits of the census method.

Ans: (a) Census method requires a large number of enumerators which is not easily available.

(b) There is a possibility of statistical errors as the investigator deals with a large volume of data.

7.What is random sampling?

Ans: Random sampling is that type of method where every item of the universe has equal chance of being selected in the sample.

8. State the method which should be used in case of infinite population.

Ans: Sampling method.

9. State the method which estimates the population in a country.

Ans: Census method.

10. What are non-sampling errors?

Ans: Non-sampling errors occur in any type of survey whether it be census or sample method.

11. What are sampling errors?

Ans: Sampling error is the difference between the result of studying a sample and the result of the census of the whole population.

12. What is the measure of central tendency?

Ans: Measures of central tendency describe the tendency of indi- vidual items to cluster or concentrate around the centre in a frequency distribution.

13. What is systematic sampling?

Ans: Systematic sampling is the method where units of the population are numerically, geographically and alphabetically arranged. Every nth item of the numbered is selected as a sample item.

14.  Define mode.

Ans: The value which occurs most frequently in series is known as mode.

15. Give the meaning of median.

Ans: Median is the middle value of a series when it is arranged either in ascending or descending order.

16. What is meant by dispersion?

Ans: Dispersion indicates the extent to which the individual val- ues fall away from the central value.

17. What does harmonic mean?

Ans: Harmonic mean is a type of average that is calculated by dividing the number of values in a data series by the sum of the reciprocals of each value in the data series.

18. Define range.

Ans: Range is defined as the difference between the largest and the smallest item in a distribution.

19. Mention any two demerits of standard deviation.

Ans. (i) Standard deviation is difficult to calculate.

(ii) It is affected by extreme values.

(B) Short Question and Answer

1. What are the essentials of a sample investigation?

Ans: The essentials of sampling are-

(a) The sample must truly represent the population.

(b) The size of the sample must be adequate.

(c) The sample unit should be selected randomly and independently.

(d) The population must be homogenous.

2. What are the purpose of average in the statistical method?

Ans: The purpose of average in the statistical method are-

(a) Brief description

(b)Comparison

(c) Formulation of policies

(d) Statistical analysis

(e) One value of all.

3. Explain briefly the random methods of collecting samples.

Ans: The various random sampling methods are-

(i) Simple random sampling: A simple random sampling is one in which every item of the population has an equal chance of being selected. Under this, the following methods are used- (a) Lottery method (b) Use of random number table.

(ii) Restricted random sampling: In case of heterogenous population, it becomes necessary to select a random sample under certain restriction. Such samples are known as 'restricted random samples'. Some of important random sampling under this category are -

(a) Stratified random sampling (b) Systematic sampling (c) Cluster sampling (d) Multistage sampling.

4. Discuss the non-random methods of sampling.

Ans: Under a non-random sampling method, the selection of a sample depends on the judgment of the investigator rather than on choice. This method does not provide every item in the universe with a known chance of being included in the sample. If the investigator is unbiased and intelligent, the selected sample may be more representative of the popula- tion than a random sample. The main methods of nonrandom sampling are-

(i) Judgement sampling

(ii) Quota sampling

(iii) Convenience sampling.

5. Discuss the precautions to be considered while mak- ing use of secondary data.

Ans: The following precautions are to be considered while mak- ing use of secondary data-

(i)The authority which has collected the data should be reli- able and dependable.

(ii) The purpose of the inquiry under investigation should have uniformity with the original purpose for which data are collected.

(iii) The interval between the time periods, when data are origi- nally collected to the time when it is going to be used should not be much.

(iv) The definition of units in which the data were collected.

(v) There should not be a significant variation between the degree of accuracy required for the present purpose and the original data.