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Thursday, May 25, 2017

Research Methodology Notes - Sampling and Questionnaire

Unit – 3: Sampling and Questionnaire

Meaning, Features and Types of Sampling
According to Goode and Hatt, “A sample as the name applies, is a smaller representative of a large whole”.  According to Pauline V Young, “A statistical sample is a miniature of cross selection of the entire group or aggregate from which the sample is taken”.  According to Bogrdus, “Sampling is the selection of certain percentage of a group of items according to a predetermined plan”.
Feature of Sampling Techniques:  The sampling techniques have following good features and these bring into relief its value and significance:
(a)    Scientific Base:  It is a scientific because the conclusion derived from the study of certain units can be verified from other units.  By taking random sample, we can determine the amount of deviation from the norm.
(b)   Economy:  The sampling technique is much less expensive,  much less time consuming than the census technique.
(c)    Reliability:  If the choice of sample unit is made with due care and the matter under survey is not heterogeneous, the conclusion of the sample survey can have almost the same reliability as those of census survey.
(d)   Detailed study: Since the number of sample units is fairly small, these can be studied intensively and elaborately. They can be examined from multiple of views.
(e)   Greater Suitability in most Situations:  Most of the surveys are made by the techniques of sample survey, because whenever the matter is of homogeneous nature, the examination of few units suffices.  This case in majority of situations.

Methods of Sampling: The methods of selecting a sample are as follows:

(a) Purposive sampling:  In this method the investigator has complete freedom to choose his sample according to his wishes and desire.  To choose or leave an item for the purpose of study depends entirely upon the wishes of investigator and he will chose items or units which in his judgment are representative of the whole data.  This is a very simple technique of choosing the samples and is useful in cases where the whole data is homogeneous and the investigator has full knowledge of the various aspects of the problem.

Ø  More representation is possible in this method.
Ø  As sample is small in size, the method is less expensive and less time consuming.
Ø  The utility of this method increases when few units of universe have special importance.
Ø  When units are less in number, sample is profitable
Ø  Units are selected by researcher at his will.  Hence sample is biased.
Ø  The error of the sample can not be detected.
Ø  Researcher is unable to understand the whole group.
Ø  Those hypothesis on which inference of error of sample is attributed, are less used.

(b) Random Sampling: Off all the methods of selecting sample, random sampling technique is made maximum use of and it is considered as the best method of sample selection.  Random sampling is made in following ways:
(i) Lottery Method: In this the number of data are written on sheet of paper and they are thrown into a box.  Now a casual observer selects the number of item required in the sample.  For this method it is necessary that sheet of paper should be of equal dimensions.
(ii) By Rotating the Drum:  In this method, piece of wood, tin or cardboard of equal length and breadth, with number 0,1 or 2 printed on them, are used. The pieces are rotated in a drum and then requisite numbers are drawn by an impartial person. 
(iii) Selecting from Sequential List:  In this procedure units are broken up in numerical, alphabetical or geography sequence.  Now we may decide to choose 1, 5, 10 and so on , if the division is alphabetical order we decide to choose every item starting from a, b, c and so on.
(iv) Tippet’s Number:  On the basis of population statistics, Tippet has constructed a random list of four digits each of 10, 400 institutions.  These numbers are the result of combining 41,600 population statistics reports.
Ø  Due to impartiality, there is possibility of selecting any unit as sample.
Ø  Units have the characteristic of universe, hence units are more representative.
Ø  Simplicity of method makes no possibility of error.
Ø  Error can be known easily
Ø  It saves money, time and labour.
Ø  The selector has no control over the selection of units. The researcher can not contact the far situated units.
Ø  He can not prepare the whole field when the universe is vast.
Ø  If units have no homogeneity, the method is not appropriate.
Ø  There is no question of alternatives.  The selected units can not be replaced or changed.
(c) Stratified Sampling:  This method of selecting samples is a mixture of both purposive and random sampling techniques. In this all the data in a domain is spilt into various classes on the basis of their characteristics and immediately thereafter certain items are selected from these classes by the random sampling technique.  This technique is suitable in those cases in which the data has sub data and having special characteristics. For example if we wish to collect information regarding income expenditure of the male population strata on the basis of shopkeeper, workers, etc.  From these we shall select randomly some units for study of income-expenditure statistics.
Process of Stratifying:   The stratification of domain or data should be with great care, because the success of the technique depends upon successful stratification.  Following points should be born in mind:
a.       We should process extensive information of all items including in a domain and should know which item make a coherent whole on the basis of similar traits and which others re different from them and why?
b.      The size of each stratum should be large to enable use of random sampling technique.
c.       In stratifying it must be kept in mind that various strata should have similar relation to the domain and should be themselves homogeneous.
d.      The various strata should differ from each other should be the same as the proportion of stratum from the domain.  Suppose a domain has four strata, accordingly the proportion of each stratum of domain is ¼.  Now if the number of total items of the sample is 64, we shall select 16 items from each stratum and thus the proportion of selected items from each stratum will be ¼.
Ø  Neither group nor class of importance is totally neglected as units of each are represented in the sample.
Ø  If different classes are divided properly, selection of few units represents the whole group.
Ø  On the classification of regional basis, units are not in contact easily. This leads to economy of time and money.
Ø  There is a facility in substitution of units. If someone is not contacted easily, the other person of the same class can be substituted for him.  Such inclusion result will not show any contradicting.
Ø  The sample does not become representative if selected sample has more or less units of a class.
Ø  If the sizes of different group are different, no equal proportional quality can be viewed.
Ø  Non-proportional selection leads to more emphasis in the end.  During such time researcher ca be biased, hence samples will not representate.
Ø  If group is not expressed properly, the difficulty is seen about the unit to be kept under which group or class.
(d) Quota Sampling:  This method of study is not much used. In this method entire data is spilt into as many as there are investigators and each investigator is asked to select certain items from his block and study.  The success of this method depends upon the integrity and professional competence of investigators.  If some investigators are competent and others are not so competent, serious discrepancies will appear in the study.
(e) Multi-Stage sampling:  This is not a favoured procedure of sampling.  In this items are selected in different stages at random.  For example, if we wish to know per acre yield of various crops in U.P., we shall begin by studying a single crop in one study.  Here we shall begin by making at random selection of 5 districts in the first instance, and then of these 5 districts, 10 villages per districts will be chosen in the same manner. Now in the final stage, again by random selection 5 fields out of every village. Thus we shall examine per acre yield in 250 farms all over U.P. this number can increased or decreased depending upon the opinion of experts.
(f) Extensive sampling:  This method is virtually same as census except that irrelevant or irascible items are left out.  Every other item is examined.  For instance, if we are to study the educational levels of Indians, we may leave foreigners living in India from our study.  This method has all the merits and demerits of census survey and is very rarely used. 
(g) Convenience Sampling:   This is hit or miss procedure of study.  The investigator selects certain item from the domain as per his convenience.  No planned efforts are made to collect information. This is method by which a tourist studies generally the country of his visit.  He comes across certain people and things, has transaction with them and then tries to generalize about the entire populace in his travelogue.  This is essentially unscientific procedure and has no value as a research technique. 
Questionnaire Method
In this method a list of questions pertaining to the survey is prepared and sent to the various informants by post. The questionnaire contains questions and provides space for answers.  A request is made to the informants through a covering letter to fill up he questionnaire and send it back within a specified time.  This method is adapted by private individuals, research workers, private and public organisations and even by govt.
Merits:  This method is most extensively employed in various economic and business surveys. The main merits are as follows:
a)      There is low cost even when the universe is large and is widely spread geographically.
b)      It is free from the bias of the interviewer; answers are in respondent’s own words.
c)       Respondents have adequate time to give well out answers.
d)      Respondents who are not easily approachable can also be reached conveniently.
e)      Large sample can be made use of and thus the results can be more dependable and reliable.
a)      Low rate of return of the duly filled in questionnaires, bias due to no-response is often indeterminate.
b)      It can be used only when respondents are educated and cooperating.
c)       There is inbuilt inflexibility because of the difficulty of amending the approach once questionnaires have been sent.
d)      The control over questionnaire may be lost once it is sent.
e)      There is also the possibility of ambiguous replies or omission of replies altogether to certain questions, interpretation of omission is difficult.
f)       It is difficult to know whether willing respondents are truly representative.
g)      This method is likely to be the slowest of all.
Requirement of good Questionnaire: The following general principle/requirements are useful in framing questionnaire:
a)      Covering Letter: The person conducting the survey must introduce himself and state objective of the survey.  A short letter stating the purpose of survey should be enclosed along with the questionnaire.
b)      Number of questions: The number of questions to be included in the questionnaire would strictly depend upon the object and the scope of the investigation and number of the questions should be as small as possible.  Because if the questionnaire is lengthy, the rate of response will be lower.
c)       Should be Arranged Logically: The question should be arranged logically so that a natural and spontaneous reply to each is induced. For example it is illogical to ask a person about his income before asking him whether he is employed or not.
d)      Short and Simple: The question should be short and simple to understand and technical terms should be avoided.
e)      Personal Question:  Personal question should be avoided such as income, income tax is paid etc.
f)       Necessary Instructions: The instructions about the unit of measurement or the time within which questionnaire should be sent back etc should be provided.
g)      Objective Answers: The descriptive questions should be avoided while framing the questionnaire.  As far as the question should be of such nature that can be answered easily in ‘yes’ or ‘no’.
h)      Calculation: Question requiring calculation should be avoided. If calculus is included, informant may not answer the questions.
i)        Attractive: The quality of paper used and printing should be of high quality. Sufficient space should be given for answering.
Designing a questionnaire AND ITS TYPES
Quite often questionnaire is considered as the heart of a survey operation. Hence it should be very carefully constructed. If it is not properly set up, then the survey is bound to fail. This fact requires us to study the main aspects of a questionnaire viz., the general form, question sequence and question formulation and wording. Researcher should note the following with regard to these three main aspects of a questionnaire:
1. General form: So far as the general form of a questionnaire is concerned, it can either be structured or unstructured questionnaire.
Structured questionnaires are those questionnaires in which there are definite, concrete and pre-determined questions. The questions are presented with exactly the same wording and in the same order to all respondents. Resort is taken to this sort of standardisation to ensure that all respondents reply to the same set of questions. The form of the question may be either closed (i.e., of the type ‘yes’ or ‘no’) or open (i.e., inviting free response) but should be stated in advance and not constructed during questioning. Structured questionnaires may also have fixed alternative questions in which responses of the informants are limited to the stated alternatives. Thus a highly structured questionnaire is one in which all questions and answers are specified and comments in the respondent’s own words are held to the minimum. When these characteristics are not present in a questionnaire, it can be termed as unstructured or non-structured questionnaire. More specifically, we can say that in an unstructured questionnaire, the interviewer is provided with a general guide on the type of information to be obtained, but the exact question formulation is largely his own responsibility and the replies are to be taken down in the respondent’s own words to the extent possible; in some situations tape recorders may be used to achieve this goal.
Structured questionnaires are simple to administer and relatively inexpensive to analyse. The provision of alternative replies, at times, helps to understand the meaning of the question clearly. But such questionnaires have limitations too. For instance, wide range of data and that too in respondent’s own words cannot be obtained with structured questionnaires. They are usually considered inappropriate in investigations where the aim happens to be to probe for attitudes and reasons for certain actions or feelings. They are equally not suitable when a problem is being first explored and working hypotheses sought. In such situations, unstructured questionnaires may be used effectively. Then on the basis of the results obtained in pretest (testing before final use) operations from the use of unstructured questionnaires, one can construct a structured questionnaire for use in the main study.
2. Question sequence: In order to make the questionnaire effective and to ensure quality to the replies received, a researcher should pay attention to the question-sequence in preparing the questionnaire. A proper sequence of questions reduces considerably the chances of individual questions being misunderstood. The question-sequence must be clear and smoothly-moving, meaning thereby that the relation of one question to another should be readily apparent to the respondent, with questions that are easiest to answer being put in the beginning. The first few questions are particularly important because they are likely to influence the attitude of the respondent and in seeking his desired cooperation. The opening questions should be such as to arouse human interest. The following type of questions should generally be avoided as opening questions in a questionnaire:
1. questions that put too great a strain on the memory or intellect of the respondent;
2. questions of a personal character;
3. questions related to personal wealth, etc.
Following the opening questions, we should have questions that are really vital to the research problem and a connecting thread should run through successive questions. Ideally, the question sequence should conform to the respondent’s way of thinking. Knowing what information is desired, the researcher can rearrange the order of the questions (this is possible in case of unstructured questionnaire) to fit the discussion in each particular case. But in a structured questionnaire the best that can be done is to determine the question-sequence with the help of a Pilot Survey which is likely to produce good rapport with most respondents. Relatively difficult questions must be relegated towards the end so that even if the respondent decides not to answer such questions, considerable information would have already been obtained. Thus, question-sequence should usually go from the general to the more specific and the researcher must always remember that the answer to a given question is a function not only of the question itself, but of all previous questions as well.

3. Question formulation and wording: With regard to this aspect of questionnaire, the researcher should note that each question must be very clear for any sort of misunderstanding can do irreparable harm to a survey. Question should also be impartial in order not to give a biased picture of the true state of affairs. Questions should be constructed with a view to their forming a logical part of a well thought out tabulation plan. In general, all questions should meet the following standards—(a) should be easily understood; (b) should be simple i.e., should convey only one thought at a time; (c) should be concrete and should conform as much as possible to the respondent’s way of thinking. (For instance, instead of asking. “How many razor blades do you use annually?” The more realistic question would be to ask, “How many razor blades did you use last week?” Concerning the form of questions, we can talk about two principal forms, viz., multiple choice question and the open-end question. In the former the respondent selects one of the alternative possible answers put to him, whereas in the latter he has to supply the answer in his own words. The question with only two possible answers (usually ‘Yes’ or ‘No’) can be taken as a special case of the multiple choice question, or can be named as a ‘closed question.’ There are some advantages and disadvantages of each possible form of question. Multiple choice or closed questions have the advantages of easy handling, simple to answer, quick and relatively inexpensive to analyse. They are most amenable to statistical analysis. Sometimes, the provision of alternative replies helps to make clear the meaning of the question. But the main drawback of fixed alternative questions is that of “putting answers in people’s mouths” i.e., they may force a statement of opinion on an issue about which the respondent does not infact have any opinion. They are not appropriate when the issue under consideration happens to be a complex one and also when the interest of the researcher is in the exploration of a process. In such situations, open-ended questions which are designed to permit a free response from the respondent rather than one limited to certain stated alternatives are considered appropriate. Such questions give the respondent considerable latitude in phrasing a reply. Getting the replies in respondent’s own words is, thus, the major advantage of open-ended questions. But one should not forget that, from an analytical point of view, open-ended questions are more difficult to handle, raising problems of interpretation, comparability and interviewer bias.

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