CENSUS METHOD OF DATA COLLECTION In census method of data collection, all the elements or cases of the field of study area are enumerated. The information is collected from all the possible units in the universe in the census method. In this method of data collection, we have to apply the technique of total counting of possible units. For example: if the average daily expenditure of students of NIMS college is to be calculated, then daily expenditure figures would be obtained from each and every student of NIMS college. Then total expenditure is divided by total number of students and we get average expenditure.
Merits:1. Complete information can be obtained about the whole populations.2. Data obtained from this method are more accurate, reliable and representatives.3. In census method, no item is left out. So, the data will be adequate.4. This method is quite useful when the field of study is not big and intensive (lot of work to be done in a short time) survey is to be made.5. Data obtained from the complete enumeration can be used in various investigations.
Demerits:1. It is more expensive, labour and time consuming method of data collection.2. It is not applicable if the population size is infinite or very large in size.3. It contains errors due to non-response, biasness of respondents.4. Some errors or wrong information may enter in an inquiry due to less efficiency of enumerator.5. It is not reliable if it destroys each and every item at the time of testing.
SAMPLING METHOD OF DATA COLLECTION The representative parts of the population is called sample. If the investigation is done by using the representative parts of the population then it is known as sampling method of data collection. Based on this sample, inference is drawn for the entire population. In this method, a part is selected from the population and examined, then it is called sample enumeration or sample survey. Sample survey will usually be less expensive than a census survey and the desired information will be obtained in less time.
Less expensive does not imply that economy is the consideration in conducting sample survey. It is most important that a degree of accuracy is also maintained. Occasionally, the techniques of sampling survey is applied to verify the result obtained from census survey. It has been well established fact that in many situations a well conducted sample survey can provide much more precise result than from census survey. In this method only selected sample represents the whole population.
For example: if we are going to study about the spending behaviour of the students who are studying management in Kathmandu. Then, among all students studying management in Kathmandu we select only 500 students under study. This 500 students are the sample of whole possible number of students studying management in Kathmandu. On the basis of spending behaviour of this 500 students, we can draw conclusion for whole population. The main objectives of this method is to draw conclusion about whole population by taking small units of population.
Examples of sampling which we can face in our daily life are: A cook tastes some pieces of rice or pulse whether it is properly cooked or not. A pathologist or doctor examines few drops of blood to draw the conclusion about the blood constitution of the whole body. A business man gives order for the commodities by examining only small sample of the same commodity.Merits:1. Reduce cost, manpower and time of the survey.2. Greater speed of getting result.
3. More trained and skilled manpower can be used so there is chances of getting greater accurate result.4. This method is very useful to check the reliability of census survey.5. If population size is very large, then this is the only appropriate method of data collection and taking correct result.Demerits:1. The sample should be collected by experts. Otherwise, the result provides wrong conclusion.
2. If the investigator is biased in the process of data collection. Then, it does not provide reliable and accurate result.3. If the sample selected from the population is not the representative one, then it may yield wrong conclusion.4. Selection of sample units and sample size is difficult task.5. If there is lack of full co-operation between enumerator and informants, at that situation we can get wrong information. Which, affects the result of the investigation.
METHODS OF SAMPLING On the basis of objective of investigation, nature of the available data, time and cost, we have to select actual method of sampling. There are various methods of sampling used in practice, which should be known before taking the sample. The sampling procedures that are commonly used may be broadly classified under two headings:A. Probability SamplingB. Non-Probability Sampling
A. Probability Sampling Probability sampling is a scientific method of selecting samples from the population based on some laws of chance, in which each unit in population has some probability of being selected in the sample. It can be categorized under following categories:a. Simple Random Sampling.b. Stratified Random Sampling.c. Systematic Sampling.d. Cluster Sampling.e. Multi-Stage Sampling.
B. Non-Probability Sampling The selection of samples without any probability rule is called non-probability sampling. In this method investigator selects sample from the population by using his own experience and judgement. Some of the non-probability samplings are:a) Judgement or Purposive Sampling.b) Accidental Sampling.c) Convenient Sampling.d) Quota Sampling.e) Snowball Sampling.