sampling process and collection of data[1]

8/8/2019 Sampling Process and Collection of Data[1]

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MODULE 3MODULE 3

STATISTICAL TOOLS IN RESEARCHSTATISTICAL TOOLS IN RESEARCH

Sampling ProcessSampling Process

Collection of dataCollection of data


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THE SAMPLING PROCESSTHE SAMPLING PROCESS

The Concept of Sampling

Sampling is defined as the process of selecting a

few from a bigger group to become the basis for

estimating or predicting a fact, situation oroutcome regarding the bigger group.

Sampling is also defined as the process of

selecting suitable or representative samples used

for the purpose of determining the characteristics

or properties of the whole population (Webster,

1986)


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SAMPLESAMPLE

defined as any aggregate drawn from a population

(Ferguson, 1976)

It is a small group that is observed while the

population is the larger group about which thegeneralization is made.

It must be adequate in size in order to produce

reliable results.

It should validly represent the whole population

involved in the study.


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POPULATIONPOPULATION

It is the group to which the results will be

generalizable.

It consists of attributed qualities and behavior of a

people or inanimate objects or opinions of peoplecomposing a nation. (Sanchez, 1997)


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STEPS USED IN SAMPLINGSTEPS USED IN SAMPLING

identification of the population

determination of the required sample size

election of the sample


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SAMPLING TECHNIQUESSAMPLING TECHNIQUES

Types of Sampling Techniques

The Probability Sampling - the ratio of the

number of outcomes produced in a given

population taken from the total population(Webster, 1986).

The Non-Probability Sampling - uses no system

of selecting samples and therefore, there is no

guarantee of equal chances of representation in

the samples. Hence, the samples taken may not be

the representative samples of the population


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A. THE PROBABILITY SAMPLINGA. THE PROBABILITY SAMPLING

Classification of Probability Sampling Random Sampling is the drawing of samples of the study which gives

each participant equal chance of being selected. To do randomsampling it is necessary to define the population, list all members ofthe population and then select the sample by employing adequate

procedure. Systematic sampling is the technique of choosing the samples from

the population after determining the sample size of the study whereeach class is treated as a different population. It is done by listing thenames of the identified samples following a logical, systematic oralphabetical or whatever acceptable arrangement.

Cluster sampling involves the selection of samples involving a clusteror a group and it is usually applied on a geographical basis in aheterogeneous population. This sampling is sometimes called areasampling because it is frequently applied on a geographical basis.


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CLASSIFICATION OF THE NONCLASSIFICATION OF THE NON--

PROBABILITY SAMPLINGPROBABILITY SAMPLING

Convenience or accidental sampling - involvesthe selection of the samples based on theconvenience of the researcher

Purposive or deliberate sampling - samples areselected based on the decision or judgment of theresearcher on who best qualifies to answer theobjectives of the study

Quota sampling - identifies quota or number ofsamples to be involved in the study with thequalities proportionate to the population of thestudy


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WAYS TO DETERMINE THE SAMPLE SIZEWAYS TO DETERMINE THE SAMPLE SIZE1. Use of formula:

n= N where n = size of the sample

1+(N)(e)2 1 = constant N = size of population

e = desired margin of error

example: Determine the sample size if the total population of the study is 5000 using a 5% marginor error.

n = 5000

1+5000 (0.5)

n = 5000

1+5000(.0025)n = 5000

1+12.5

n = 500013.5

n = 370 The sample size is 370 respondents


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2.2. USE OF PERCENTAGEUSE OF PERCENTAGE

Gay (1976) give some minimum sizes

Descriptive research 10% of a large population of

1,000 or more; 20% for a small number of population of

500 and less. Correlational research 30 subjects

Experimental research 15 subjects per group of 30 per

group as preferred by some authorities

Ex post facto or causal comparative 15 subjects pergroup


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USE OF SPECIFIC MARGIN OF ERRORUSE OF SPECIFIC MARGIN OF ERRORPopulation Margin of Error / Sample

Representative

+1% +2% +3% +4% +5% +10%

500 NA NA NA NA 222 83

1,500 NA NA 638 441 316 94

2,500 NA 1,250 769 500 345 96

3,000 NA 1,364 811 517 353 97

4,000 NA 1,538 870 541 364 98

5,000 NA 1,667 909 556 370 98

6,000 NA 1,765 938 566 375 98

7,000 NA 1,842 956 574 378 99

8,000 NA 1,908 976 580 381 99

9,000 NA 1,908 989 584 383 99

10,000 5,000 2,000 1,020 588 388 99

50,000 8,333 2,333 1,807 617 387 100


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COLLECTION OF DATACOLLECTION OF DATA

Data are the things we think with. They are the

raw materials of reflection, until by comparison,

combination and evaluation they are stepped up to

higher levels of generalization, where again theyserve as basic materials for higher thinking.

(Whitney, 1950).


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Structured self reporttechniques utilize a formal

written document which is usually referred to as

instrument.

interview schedule - when answered orally questionnaire - when answered using a paper and

pencil


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CLASSIFICATION OF DATACLASSIFICATION OF DATA

objective or subjective

quantitative or qualitative

attributes or variables

methods and types of research that the researcher

may use, e.g. historical, experimental, descriptive,

sociological and so on

primary or secondary raw or derived.


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SOURCES OF DATASOURCES OF DATA

Manuscripts

Relics

Fossils

Books Pamphlets

Magazines

Newspapers

Monuments and all kinds of specimen within human reach and

interpretation.


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CLASSIFICATION OF SOURCES OF DATACLASSIFICATION OF SOURCES OF DATA

(BEST, 1981)(BEST, 1981)

primary sources - official records of legislative

bodies, departments, school officials, minutes of

board meetings, annual bulletins course study,

curriculum guides, report cards and the like secondary sources - reports of a person on the

testimony of an actual witness of participant in an

event, history textbooks, encyclopedias and other

similar second hand account


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TOOLS OR TECHNIQUES USED IN THETOOLS OR TECHNIQUES USED IN THE

COLLECTION OF DATACOLLECTION OF DATA

A. Observation - considered as one of the oldest forms of

studying behavior

B. The Interview - a data-gathering device which enables

the researcher to draw information from the subject or

interviewee verbally in a face-to-face relationship.

C. Inquiry Forms


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TYPES OF OBSERVATIONTYPES OF OBSERVATION

Naturalistic observation - means watching and

describing behavior as it occurs in its natural

setting.

Participant observation - the person doing theresearch becomes actively involved in the lives of

the people being observed, thus, participant

observation is obtrusive.


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CHARACTERISTICS OF GOOD OBSERVATIONCHARACTERISTICS OF GOOD OBSERVATION

Observation should be carefully planned, systematic, and

perceptive

Observers should note the important details

Observers should be objective

Observers should separate the facts from the interpretation of

the facts

Observers should check and verify their observations with those

of other competent observers.

Observers should use appropriate instruments to systematize,quantify, and carefully record the results of their observations.

Observers should ensure that their observations are valid and

reliable.


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TYPE OF INTERVIEW ACCORDING TOTYPE OF INTERVIEW ACCORDING TO

STYLESTYLE

Formal Interview - utilizes an interview schedule

which consists of standard set of questions.

Answer sheet is also provided where answers to

specific questions may be written. Informal Interview - the interviewer is guided by

the interview guide which provides some salient

points on which the interview is focused


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IMPORTANT POINTS TO BE CONSIDERED INIMPORTANT POINTS TO BE CONSIDERED IN

THE CONDUCT OF INTERVIEWTHE CONDUCT OF INTERVIEW

Preparation- involves the preparation of an interview

guide, interview schedule and identification of possible

strategy to be used in the conduct of interview

Know the appropriate place and time for interview.

Select an ideal, comfortable place free from noise and

distraction and time, where, and when to conduct the

interview.

Develop rapport. The interviewer should develop

harmonious, friendly and cordial atmosphere with theinterviewee.


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Sustaining the interview - the interview should learn to

carry on the conversation smoothly until the end of the

interview by using some key words that will help sustain

the interview

Interview Recording - a portable tape recorder could be

used to accurately document the interview but permission

to use one should be requested from the interviewee.

Clarification of the statements is made by the interviewee.

closing the Interview. The interviewer should end theinterview with the expression of deep gratitude and

appreciation for the time, effort and generosity of the

interviewee in providing information relevant to the study.


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Inquiry Forms

Questionnaire - defined by Good (1954) as a list

of planned, written questions related to a

particular topic, with space provider for indicating

the response may be sent by mail to individualswho are called respondents but it can also be

administered personally to groups of individuals

The Opinionnaire - or attitude scale measures

the attitude or belief of an individual.


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TYPES OF QUESTIONNAIRETYPES OF QUESTIONNAIRE

Structured - structured questionnaire asks a

question and provides several possible answers

Unstructured - primarily asks questions, but no

suggested answers are given by the investigator.According to Nutt et. al (1966)it provides more

freedom to the respondents but are difficult to

analyze when large groups of subjects are used.

The decision as to which type of questionnaire

to use is based on the problem being studied and

other practical factors.


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PRINCIPLES IN CONSTRUCTING APRINCIPLES IN CONSTRUCTING A

QUESTIONNAIREQUESTIONNAIRE

Define or qualify terms that could easily be misinterpreted.

Be careful in using descriptive adjectives and adverbs that have

no agreed-upon meaning.

Be careful of inadequate alternatives

Avoid double negatives.

Avoid the double-barreled question

Underline a word if you wish to indicate special emphasis

Avoid unwarranted assumptions.

Phrase questions so that they are appropriate for allrespondents.

Design questions that will give a complete answer.

Provide for the systematic quantification of responses.

Consider the possibility of classifying the responses.


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CHARACTERISTICS OF A GOODCHARACTERISTICS OF A GOOD


It deals with a significant topic, on which the respondent will

recognize as important enough to warrant spending his time on.

It seeks only information which cannot be obtained from other

sources such as school reports or census data.

It is as short as possible only long enough to get the essentialdata.

It is attractive in appearance, neatly arranged, and clearly

duplicated or printed.

Directions are clear and complete, important terms are defined,each question deals with a single idea, all questions are worded

as simply and as clearly as possible, and the categories provide

an opportunity for easy, accurate and unambiguous responses.


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The questions are objective, with no leading suggestions as to

the responses desired.

Questions are presented in good psychological order, proceeding

from general to more specific responses. If possible,

embarrassing questions should be avoided. The responses are easy to tabulate and interpret.


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TYPES OF QUESTIONS IN PREPARATION OFTYPES OF QUESTIONS IN PREPARATION OF

THE QUESTIONNAIRETHE QUESTIONNAIRE

Open-ended Question or Free response questions. This

type will freely allows the respondents to express

themselves on the issue or the problem raised regarding

the study. The questions frequently asked are what, why

and how.

Closed Type or structural form of Questionnaire. It is

also called fixed alternative questions. It provides a list of

choices among enumerated alternatives as answers to the

specific question raised in the study.


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CRITERIA IN PREPARATION OF THECRITERIA IN PREPARATION OF THE


Knowing the two types of questions.

Utilize the knowledge and information you will gather from

the review of related literature.

Talk with persons who are knowledgeable on the

construction of the questionnaire can also help in the

preparation of the questionnaire such as your professors,

department heads or the deans of your college or university

officials.

Make the draft of your questionnaire and then submit it toyour advisers and other professors for comments and

suggestions.

Test the validity and reliability of your questionnaire using

dry-run.


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GUIDE IN ADMINISTERING THEGUIDE IN ADMINISTERING THE


Choose respondents carefully.

Secure the approval of the appropriate authorities

If the desired information is delicate or intimate in

nature, consider the possibility of providing foranonymous responses.

Try to get the aid of sponsorship.

Include a courteous and carefully constructedcover letter to explain the purpose of the study

Make a vigorous follow-up to increase the number

of returns.


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QUALITIES OF A GOOD INSTRUMENTQUALITIES OF A GOOD INSTRUMENT

Validity - measures what it claims to measure

Reliability - measures consistently, from one time to

another whatever it should measure

Sensitivity - the ability of an instrument to makediscriminations required for the resource problem

Objectivity - the degree to which the measure is

independent of personal opinions, subjective

judgment, biases and beliefs of the individual test user Feasibility - concerns the skills, cost and time needed

in preparing the test


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TYPES OF VALIDITYTYPES OF VALIDITY

1. Content validity shows how adequately the test

samples the universe of knowledge, attitudes, and skills

that a student is expected to master.

2. Construct validity is the degree to which scores on a

test can be accounted for by the explanatory constructs

of a sound theory.

3. Criterion-related validity is a broad terms that refers

to two different criteria.

a. predictive validity - which refers to the usefulness of a test in

predicting some future performance.

b. concurrent validity - which refers to the usefulness of a test


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sampling process and collection of data[1]

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