Dr Kishor BhanushaliAssociate Professor

Unitedworld School of Business

Mob: 9898422620Email: kishorkisu@gmail.com

Rai University , May 2015 Ph.D. Coursework of Research Methodology

Sampling Fundamentals

SamplingSampling may be defined as the

selection of some part of an aggregate or totality on the basis of which a judgement or inference about the aggregate or totality is made.

In other words, it is the process of obtaining information about an entire population by examining only a part of it.

NEED FOR SAMPLINGSave time and moneyAccurate measurementsOnly way for infinite populationOnly choice when a test involves

the destruction of the itemSampling usually enables to

estimate the sampling errors and, thus, assists in obtaining information concerning some characteristic of the population.

SOME FUNDAMENTAL DEFINITIONSUniverse/PopulationSampling frameSampling designStatistics and parametersSampling error Confidence level and significance

levelSampling distribution

IMPORTANT SAMPLING DISTRIBUTIONSSampling distribution of meanSampling distribution of

proportionStudent’s t-distributionF distributionChi-square distribution

CENTRAL LIMIT THEOREMWhen sampling is from a normal

population, the means of samples drawn from such a population are themselves normally distributed

The significance of the central limit theorem lies in the fact that it permits us to use sample statistics to make inferences about population parameters without knowing anything about the shape of the frequency distribution of that population other than what we can get from the sample.

CONCEPT OF STANDARD ERROR

The standard deviation of sampling distribution of a statistic is known as its standard error (S.E) and is considered the key to sampling theory.

SAMPLE SIZE AND ITS DETERMINATIONNature of universeNumber of classes proposedNature of studyType of samplingStandard of accuracy and acceptable

confidence levelAvailability of financeOther considerations: (a) Nature of units, (b)

size of the population, (c)size of questionnaire, (d) availability of trained investigators, (e)the conditions under which the sample is being conducted, (f) the time available for completion of the study.

Sampling Design

CENSUS AND SAMPLE SURVEY

A complete enumeration of all items in the ‘population’ is known as a census inquiry.

Highest level of accuracyThis type of inquiry involves a great deal of time,

money and energy.The respondents selected should be as

representative of the total population as possible in order to produce a miniature cross-section.

The selected respondents constitute what is technically called a ‘sample’ and the selection process is called ‘sampling technique.

Researcher must prepare a sample design for his study i.e., he must plan how a sample should be selected and of what size such a sample would be

STEPS IN SAMPLE DESIGNType of universeSampling unitSource listSize of sampleParameters of interestBudgetary constraintSampling procedure

CRITERIA OF SELECTING A SAMPLING PROCEDURE

Inappropriate sampling frameNon-respondentsIndeterminancy principleNatural bias in the reporting of

dataWhile selecting a sampling

procedure, researcher must ensure that the procedure causes a relatively small sampling error and helps to control the systematic bias in a better way.

CHARACTERISTICS OF A GOOD SAMPLE DESIGN

(a) Sample design must result in a truly representative sample.

(b) Sample design must be such which results in a small sampling error.

(c) Sample design must be viable in the context of funds available for the research study.

(d) Sample design must be such so that systematic bias can be controlled in a better way.

(e) Sample should be such that the results of the sample study can be applied, in general, for the universe with a reasonable level of confidence

DIFFERENT TYPES OF SAMPLE DESIGNS

COMPLEX RANDOM SAMPLING DESIGNS

Systematic samplingStratified samplingCluster samplingArea sampling Multi-stage samplingSampling with probability

proportional to sizeSequential sampling

Methods of Data Collection

The primary data are those which are collected afresh and for the first time, and thus happen to be original in character

The secondary data, on the other hand, are those which have already been collected by someone else and which have already been passed through the statistical process

COLLECTION OF PRIMARY DATA (i) observation method, (ii) interview method, (iii) through questionnaires,(iv) through schedules, and (v) other methods which include (a)

warranty cards; (b) distributor audits; (c) pantry audits; (d) consumer panels; (e) using mechanical devices; (f) through projective techniques; (g) depth interviews, and (h) content analysis.

Observation Method Most commonly used method specially in studies

relating to behavioural sciences Information is sought by way of investigator’s own

direct observation without asking from the respondent Subjective bias is eliminated, if observation is done

accurately Information obtained under this method relates to

what is currently happening Independent of respondents’ willingness to respond Very limited information Structured observation & Unstructured observation Participant observation & non-participant observation controlled & uncontrolled observation.

Personal interviewStructured interviews &

unstructured interviewsFocused interviewClinical interviewNon-directive interviewMerits & demerits of interview

methodsPre-requisites and basic tenets of

interviewing

Telephone interviewsThis method of collecting

information consists in contacting respondents on telephone itself. It is not a very widely used method, but plays important part in industrial surveys, particularly in developed regions.

Merits & demerits.

COLLECTION OF DATA THROUGH QUESTIONNAIRESQuestionnaire is sent (usually by post)

to the persons concerned with a request to answer the questions and return the questionnaire

The respondents have to answer the questions on their own

Pilot SurveyMain aspects of a

questionnaire :general form, question sequence and question formulation and wording

Essentials of a good questionnaire Short and simple Logical sequence moving from easy to more difficult

question Personal and intimate questions should be left to the end. Technical terms and vague expressions capable of different

interpretations should be avoided in a questionnaire Open-ended should be avoided Control questions in the questionnaire which indicate the

reliability of the respondent Questions affecting the sentiments of respondents should

be avoided Adequate space for answers There should always be provision for indications of

uncertainty, e.g., “Do not know,” “no preference” and so on Brief directions with regard to filling up the questionnaire

should invariably be given in the questionnaire itself Physical appearance

COLLECTION OF DATA THROUGH SCHEDULESschedules (proforma containing a set of

questions) are being filled in by the enumerators who are specially appointed for the purpose

Enumerators explain the aims and objects of the investigation and also remove the difficulties which any respondent may feel in understanding the implications of a particular question or the definition or concept of difficult terms.

Enumerators should be trained

SOME OTHER METHODS OF DATA COLLECTIONWarranty cards Distributor or store audits Pantry auditsConsumer panelsUse of mechanical devicesProjective techniques :(i) Word association

tests (ii) Sentence completion tests (iii) Story completion tests (iv) Verbal projection tests (v)Pictorial techniques(vi) Play techniques (vii) Quizzes, tests and examinations

Depth interviewsContent-analysis

COLLECTION OF SECONDARY DATA

(a) various publications of the central, state are local governments;

(b) various publications of foreign governments or of international bodies and their subsidiary organisations;

(c) technical and trade journals; (d) books, magazines and newspapers; (e) reports and publications of various associationsconnected with business and industry, banks, stock

exchanges, etc.; (f) reports prepared by research scholars, universities,

economists, etc. in different fields; and (g) public records and statistics, historical documents,

and other sources of published information

Characteristics of Secondary DataReliability of dataSuitability of dataAdequacy of data

SELECTION OF APPROPRIATE METHOD FOR DATA COLLECTIONNature, scope and object of

enquiryAvailability of fundsTime factorPrecision required

Thanks

ThanksDr Kishor BhanushaliAssociate Professor

Unitedworld School of BusinessMob: 9898422620

Email: kishorkisu@gmail.com