NON RANDOM SAMPLING METHODS

vSAMPLING TECHNIQUES 1

vNON RANDOM SAMPLING METHODS
BUSINESS STATISTICS
MARKETING RESEARCH
RESEARCH METHODOLOGY
METHOD OF DATA COLLECTION

1.       COMPLETE ENUMERATION METHOD:_ DATA ARE COLLECTED FOR EACH AND EVERY UNIT(PERSON,FIELD,SHOP,FACTORY ETC) BELONGING TO POPULATION OR UNIVERSE

2.       SAMPLE : SAMPLING IS ONLY A TOOL WHICH HELPS TO KNOW THE FEATURES OF THE UNIVERSE OR POPULATION BY EXAMINING A SMALL PART OF IT.THE VALUE OBTAINED FROM THE STUDY OF SAMPLE SUCH AS AVERAGE OR VARIANCE ARE KNOWN AS STATISTIC AND ON THE OTHER HAND SUCH VALUES FOR THE POPULATION ARE CALLED PARAMETERS.

v    MEANING OF SAMPLING

1.       AS THE PROCESS OF SELECTING CERTAIN MEMBERS OR SUBSETS OF THE POPULATION TO MAKE STATISTICAL CONCLUSIONS FROM THEM AND TO ESTIMATE CHARACTERISTICS OF THE WHOLE POPULATION.

2.       POPULATION:-CONSISTS OF THE TOTALITY OR AGGREGATE OF THE OBSERVATION WITH WHICH THE RESEARCHER IS CONCERNED. IT SHOULD BE CLEARLY DEFINED SO THAT THE SAMPLE CAN BE ACCURATELY DEFINED.

3.       SAMPLE: IS SUBSET OF THE POPULATION THAT IS SELECTED FOR STUDY

4.       SAMPLING IS THE PROCESS OF CHOOSING A REPRESENTATIVE PORTION OF THE ENTIRE POPULAION

•     TERMNIOLOGY

1.       ELEMENTS: THE MOST BASIC UNITS ABOUT WHICH INFORMATION IS COLLECTED

2.       REPRESENTATIVES MEANS THE SAMPLE MUST BE LIKE THE POPULATION IN AS MANY WAYS POSSIBLE

3.       THE SPECIFIC POPULATION TYPE:-

a.       TARGET POPULATION:-IS A GROUP OF INDIVIDUALS WHO MEETS THE CRITERIA

b.       RESPONDENT POPULATION:-GROUP OF INDIVIDUALS PARTICIPATION IN THE STUDY

4.       SAMPLING FRAME DESCRIBES THE COMPLETE LIST OF SAMPLING UNITS FROM WHICH THE SAMPLE IS TAKEN

5.       SAMPLE IS CHOSEN BY ON SOME ELIGIBILITY CRITERIA AND IT MAY INCLUDE GENDER,AGE,MARITAL STATUS INCOME ETC

6.       SAMPLING UNIT REFERS TO SPECIFIC PLACE OR LOCATION FROM WHERE DATA WILL BE COLLECTED

7.       SAMPLING FRAME:-DESCRIBES THE COMPLETE LIST OF SAMPLING UNITS FROM WHICH THE SAMPLING UNITS IS DRAWN

8.       DETERMINE THE SAMPLE SIZE

•     TYPES OF SAMPLING TECHNIQUES

1.       PROBABILITY SAMPLING: IS A SAMPLING TECHNIQUE IN WHICH SAMPLE FROM A LARGER POPULATION ARE CHOSEN USING A METHOD BASES ON THE THEORY OF PROBABILITY. IT CONSIDER EVERY MEMBER OF THE POPULATION AND SAMPLE IS SELECTED ON THE BASIC OF FIXED PROCESS

2.       NON PROBABILITY SAMPLING:-IS A SAMPLING TECHNIQUE WHERE THE SAMPLES ARE GATHERED IN A PROCESS THAT DOES NOT GIVE ALL  THE INDIVIDUALS IN THE POPULATIONS EQUAL CHANCES OF BEING SELECTED.

•     PRINCIPLE OF SAMPLING

1.       PRINCIPLE OF STATISTICAL REGULARITY:_DERIVED FROM THE MATHEMATICAL THEORY OF PROBABILITY. THIS PRINCIPLES POINTS OUT THAT IF SAMPLE IS TAKEN AT RANDOM FROM A POPULATION IT IS LIKELY TO POSSESS ALMOST THE SAME FEATURES AS THAT OF THE POPULATION. BY RANDOM SELECTION WE MEAN A SELECTION WHERE EACH AND EVERY ITEM OF THE POPULATION HAS AN EQUAL CHANCE OF SELECTED.

2.       PRINCIPLE OF INERTIA OF LARGE NUMBERS: OTHER THINGS EQUAL THE LARGER THE SIZE OF THE SAMPLE,MORE ACCURATE THE RESULTS LIKELY TO BE

•     NON PROBABILITY

1.       CONVENIENCE

2.       QUOTA

3.       PURPOSIVE OR JUDGMENTAL SAMPLING

4.       SNOWBALL SAMPLING

•     PROBABILITY

1.       SIMPLE RANDOM

2.       SYSTEMATIC

3.       STRATIFIED

4.       CLUSTER

5.       MULTISTAGE

•     CONVENIENCE /ACCIDENTALSAMPLING

•     SAMPLE IS SELECTED ACCORDING TO THE CONVENIENCE OF THE SAMPLE. THE RESEARCHER SELECTS SAMPLE WHICH IS CONVENIENT FOR HIM. IT ENSURES CONVENIENCE IN RESPECT OF  AVAILABILITY OF SOURCE LIST AND ACCESSIBILITY OF THE UNITS

•     SUITABILITY:-

1.       NO CLEAR DEFINITION OF THE UNIVERSE

2.       SAMPLING UNIT IS NOT CLEAR

3.       A COMPLETE SOURCE LIST IS NOT AVAILABLE

•     EVALUATION

•     MERITS

1.       SAVES TIME AND MONEY

2.       SAVES EFFORT

3.       EASY TO COLLECT DATA

DEMERITS

1.       NO REPRESENTATIVE

2.       POSSIBLE RESTRICTING'S OF GENERALIZATION ABOUT THE STUDY FINDING

•     JUDGMENTS SAMPLING

1.       INVOLVES THE SELECTION OF A GROUP FROM THE POPULATION ON THE BASIS OF AVAILABLE INFORMATION

2.       SELECTION OF THE GROUP  BY INTUITION ON THE BASIS OF CRITERIA DEEMED TO BE SELF EVIDENT

3.       UNITS ARE INCLUDED IN THE SAMPLE ON THE BASIS OF THE JUDGMENT

4.       IS USED WHEN SIZE OF THE SAMPLE IS SMALL.

5.       SUITABLE TO SOLVE EVERY DAY BUSINESS PROBLEMS AND MAKING PUBLIC POLICY DECISIONS.

6.       MAY BE USED TO CONDUCT PILOT STUDY

•     EVALUATION

•     MERITS

1.       SAVES THE TIME AND COST

2.       TO INCLUDE THE POSITIVE STRATIFICATION IN THE SAMPLE

DEMERIT

1.       CHANCES OF BIASEDNESS

2.       SUCCESS DEPENDS ON THE RIGHT JUDGMENT

3.       UNSCIENTIFIC

•     QUOTA SAMPLING

1.       TYPE OF JUDGMENT SAMPLING

2.       QUOTA ARE SET UP ACCORDING TO GIVEN CRITERIA BUT WITH IN THE QUOTA SELECTION OF SAMPLE ITEMS DEPENDS UPON PERSONAL JUDGMENT.

3.       LIKE IN A RADIO LISTENING SURVEY THE INTERVIEWERS MAY BE TOLD TO INTERVIEW OF 500 PEOPLE LIVING IN PARTICULAR LOCALITY AND THAT OUT OF EVERY 100 PERSONS INTERVIEWED 60 ARE TO HOUSEWIVES,25 FARMERS AND 15 CHILDREN UNDER THE AGE OF 15. WITH IN THESE QUOTA,THE INTERVIEWER IS FREE TO SELECT THE PEOPLE INTERVIEWED

•     EVALUATION

•     MERIT:_

•     COST PER PERSON WILL BE LESS

•     DEMERIT:_

a) RISK OF PERSONAL PREJUDICE

b)CHANCES OF BIASEDNESS

•     SNOW BALL SAMPLING

•      

1.       IS A WELL KNOWN NON PROBABILITY METHOD OF SURVEY SAMPLE

2.       USED FOR LOCATING HIDDEN POPULATION

3.       RELIES ON REFERRAL FROM INITIALLY SAMPLES RESPONDENTS

ADVANTAGE: COST AND EFFICIENCY

DEMERIT:

a) NON RANDOM SELECTION PROCEDURE

b)RELIES ON THE SUBJECTIVE JUDGMENT OF INFORMANTS