Census & Sample Methods of Collection of Data

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Census & Sample Methods of Collection of Data:

Census & Sample Methods of Collection of Data Chapter 3

Census Method:

Census Method Census method is that method in which data are collected covering every item of the universe or population relating to the problem under investigation. Its is based on enumeration method.

Census method:

Census method Merits The results will be absolutely accurate and reliable. Extensive information Study of diverse characteristics. It is also unbiased. Demerits It is time consuming. It is very costly. Large manpower required. And also not suitable for large investigation.

Sample Method:

Sample Method Sample method is that method in which data is collected about the sample on a group of item taken from the population for examination and conclusions are drawn on their basis. It is based on estimation method.

Sample Method:

Sample Method Merits Its takes less time and consumes less energy. Large area of investigation. It is less costlier. This method is easy and simple. Demerits It is less accurate. Conclusions can be wrong. Biased. This method cannot advantageously used in small area of investigation.

Essentials of Sample:

Essentials of Sample A sample must be REPRESENTATIVE means represents all characteristics of the entire population. The number of item in the sample should fairly ADEQUATE so that some reliable conclusions can be drawn. All units of the sample must be INDEPENDENT of each other. Inclusion of one item in the sample doe not depend on other item. In case of more than one sample, these sample should be HOMOGENOUS to each other .

Types of Sampling Method:

Types of Sampling Method RANDOM SAMPLING PURPOSIVE AND DELIBRATE SAMPLING STRATIFIED OR MIXED SAMPLING SYSTEMATIC SAMPLING QUOTA SAMPLING CONVENIENCE SAMPLING

Random Sampling:

Random Sampling Random sampling is that method of sampling in which each and every item of the universe has equal chance of being selected in the sample. Method used- Lottery method: In this method, paper slips are made for each item of the universe. Tables of random numbers: Some statisticians have prepared a set of tables called table of random numbers.

Random Sampling:

Random Sampling Merits Easy and straightforward method. Not biased. Have equal chances of being selected. Demerits Only hit and trail method. It doesn’t give much weightage to some points and guarantee proportionate representation of different items in the universe.

Purposive and Deliberate Sampling:

Purposive and Deliberate Sampling Purposive sampling is that method in which the investigator himself makes the choice of the sample items which in his opinion are the best representative of the universe. Probability of getting selected is not equal.

Purposive and Deliberate Sampling:

Purposive and Deliberate Sampling Merits According to the study or investigation. Allows selection of important items. Very simple technique of the sample items Demerits Possibility of personal bias in selection of items. Reliability of the results becomes doubtful.

Stratified Sampling or Mixed Sampling :

Stratified Sampling or Mixed Sampling This method of sampling is generally adopted when population consist of different groups with different characteristics. According to this method of sampling, population is divided into different strata having different characteristics and some of the items are selected from each strata, so that the entire population gets represented. And it is also called mixed sampling because it is a combination of random and purposive sampling.

Systematic Sampling:

Systematic Sampling According to this method, units of the population are arranged numerically, geographically and alphabetically or to ascending and descending order. Every nth item of the numbered items is selected as a sample item.

Systematic Sampling:

Systematic Sampling Merits It is a very simple method. It is free form personal bias. Demerits If all the items in the population are homogenous, then this method will be least effective. Probability of getting equal chances is less.

Quota Sampling:

Quota Sampling In this method, the population is divided into different groups or classes according of different characteristics of the population. Some percentage of different groups in total population is fixed. Investigator selects the fixed number of items from each group to frame a sample. Not very expensive. High risk of personal bias.

Convenience Sampling:

Convenience Sampling In this method, sampling is done by the investigator in such a manner that suits his convenience. This method is the simplest and least expensive, but unscientific and unreliable. Investigator can use his techniques or methods for his statistical investigation study.

Reliability of Sampling Data:

Reliability of Sampling Data Size of the sample: Not to small. Method of sampling: Must be simple Bias of correspondents and enumerators: Personal bias of these people should be as less as possible. Training of Enumerators: Trained enumerator will collect reliable data for investigation.

Census and Sampling Method: A cooperative Look :

Census and Sampling Method: A cooperative Look Some of the principal differences between census and sampling methods are as under: Coverage: In the census method, an investigator collects information relating to all the items in the population. In the sampling method, on the other hand, only some of the items which represents the population are covered for an investigation. Suitability: Census method is suitable when the area of investigation is relatively small. On the other hand, when the area of investigation is large, it is sampling method which is generally used.

Continue…:

Continue… Accuracy: There is generally a greater degree of accuracy in the results based on the census method then the sampling method. This is because in the census method each and every item of the population is studied. Cost: Sampling method is certainly much less expensive than the census method. Smaller the sample size out of the given population, lesser the cost of investigation. Time: Sample method is less time consuming than the census method. Nature of Items: Census method is particularly suitable when the item in the population are homogenous. Verification: verification of the statistical information obtained through census method id generally not possible. Sample information, on the other hand, can be easily verified .

Sampling Error:

Sampling Error The difference between sampling and census result under same circumstances is known as sample error . Can be minimized by taking large sample. Two Types: Biased errors: Errors arise due to the bias of the selector. Unbiased errors: Errors arise due to the small size of the sample not because of the biasness of the selector.

Non-Sampling Error:

Non-Sampling Error Such errors may arise intentionally or unintentionally. Arise due to negligence, lack of knowledge, non responsiveness etc. It can occur in both census or sampling method.

Hardik Arora :

Hardik Arora Thank You

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