EDU702 Research Methodology

Quantitative Research

Prepared byAzurawati Binti Wok Zaki

2011313879ED7701A2

Chapter 16:Causal-Comparative

Research

(Ex post facto ResearchNon-experimental research)

THE AIM

to determine the cause of existing differences among groups.

Causal-Comparative Research is Differentiated from Experimental

Research

• In an experiment, the independent variable is manipulated by the researcher.

• In causal comparative research the independent has already occurred.– Examples of independent variables

include socioeconomic status, pre-school history, number of siblings, and so on.

Three types of causal-comparative research

Type 1

• Exploration of effects (dependent variable) cause by membership in a given group

• Question: What differences in abilities are caused by gender?

• Research hypothesis: Females have a greater amount of linguistic ability than males.

Type 2

• Exploration of causes (independent variable) of group membership

• Question: What causes individuals to join a gang?

• Research hypothesis: Individuals who are members of gangs have more aggressive personalities than individuals who are not members of gangs.

Type 3

• Exploration of the consequences (dependent variable) of an intervention

• Question: How do students taught by the inquiry method react to propaganda?

• Research hypothesis: Students who were taught by the inquiry method are more critical of propaganda than are those who were taught by the lecture method.

Causal- comparative and Correlational Research

• Similarities: researchers explore relationship

among variablesseek identify variables that are

worthy of later exploration through experimental research.

provide guidance for subsequent experimental studies.

attempt to explore causation

Differences:Causal-Comparative vs Correlational

- Compare 2 or more groups of subjects

- Require a score on each variable for each subject.

-Involve at least one categorical variables (group membership)

- Investigate 2 (or more) quantitative variables

- Often compare averages or use crossbreak tables.

- Analyse data using scatterplots

Causal-comparative and Experimental Research

• Similarities:• - Require at least one

categorical variable (group membership).

• - Compare group performances (average score) to determine relationship.

• - Both typically compare separate group of subjects.

Differences: Causal-Comparative vs Experimental

- No manipulation takes place

- Independent variable is manipulated

- Provide much weaker evidence for causation than do experimental studies.

- The group are already formed (the researcher must locate them)

- The researcher can assign subjects to treatment groups

- The researcher has much greater flexibility in formulating the structure of the design.

Value of Causal Comparative Research

• Uncovers relationships to be investigated experimentally.

• Used to establish cause-effect when experimental design not possible.

• Less expensive and time consuming than experimental research.

• Note: if you conduct a quantitative research study it most likely will be a causal-comparative study.

• More Examples:• How does preschool attendance

affect social maturity at the end of the first grade?

• How does having a working mother affect a child’s school absenteeism?

STEPS TAKEN

1) Problem Formulation2) Sample

3) Instrumentation4) Design

Threats

• Subject Characteristics• - Matching the subjects• - Finding or Creating

Homogeneous Subgroups• - Statistical Matching

Data Analysis in Causal-Comparative Studies

• To construct frequency polygon• Means and standard deviations are

usually calculated in the variables involved are quantitative.

• The most used test is a t-test for differences between means.

• Analysis of covariance is useful.• The results should always be

interpreted with caution.

Chapter 17:Survey Research

The most popular technique for

gathering primary data in which a

researcher interacts with people to

obtain facts, opinions,

and attitudes.

The Purpose of Survey Research

To describe the characteristics of a population

To find out how the members of a population distribute themselves on

one or more variables

Rarely is the population as whole studies, however. Instead, a sample is

surveyed and a description of the population is inferred from what the

sample reveals.

3 Characteristics

Information is collected from a group of people

in order to describe some

aspects of characteristics of the population of which that group

is a part.

The main way- asking questions

Information is collected from a sample rather

than from every member of the

population.

Types of Surveysi) Cross-sectional study

• A study in which various segments of a population are sampled. E.g. managers and non-managers.

• Data are collected at a single moment in time.

• When an entire population is surveyed: Census

example

• A professor of Mathematics might collect data from a sample of all the high school mathematics teachers in a particular state about their interests in earning a master’s degree in Mathematics from his university.

ii) Longitudinal study

• Longitudinal survey• - information is collected at

different points in time in order to study changes over time.

3 Longitudinal designs

Trend study

Cohort Study

Panel Study

different samples from a population whose member may change are surveyed at different points in time.

a particular population whose members do not change over the course of the survey.

the researcher surveys the same sample of individuals at different times during the course of the survey.

Examples:

• Trend study:- A researcher might be interested in

the attitudes of high school principals towards the use of flexible scheduling. He would select a sample each year from a current listing of high school principals throughout the year. The same individual would not be the sampled each year, he would compare responses from year to year to see whether any trends were apparent.

Cohort study

• A researcher would like to study growth in teaching effectiveness of all the 1st year teachers who had graduated in the past 5 years from a university. The names of all would be listed, and different sample would be selected from this listing at different times.

Panel study

• A researcher select a sample of last year’s graduates from a university who are 1st year teachers and survey on the same individual several times during the teaching years.

Steps taken

Defining the problem

- It should be interesting and

important to motivate individuals to

respond.

Identifying the target population

Forms of Survey Research

Mail SurveysMail Surveys

Telephone surveysTelephone surveysPersonal InterviewsPersonal Interviews

Internet surveysInternet surveys

Comparison of three kinds of surveysCOMPARISON OF SURVEY TECHNIQUES

Advantages and Disadvantages Direct Administration

Tele-phone

Mail Inter-view

Comparative Cost Lowest Inter-mediate

Inter-mediate

High

Facilities needed? Yes No No Yes

Require training of questioner?

Yes Yes No Yes

Data collection time Shortest Short Longer Longest

Response rate Very high Good Poorest Very High

Group administration possible

Yes No No Yes

Allow for random sampling? Possibly Yes Yes Yes

Require literate sample? Yes No No No

Permit follow-up-questions? No Yes Yes Yes

Encourage response to sensitive topics?

Somewhat Somewhat

Somewhat

Weak

Standardization of responses Easy Somewhat

Somewhat

Hardest

Questionnaire Design

Open-EndedQuestion

Open-EndedQuestion

Closed-EndedQuestion

Closed-EndedQuestion

An interview question that encourages an answer phrased in respondent’s

own words.

An interview question that encourages an answer phrased in respondent’s

own words.

An interview question that asks the respondent to make a selection

from a limited list of responses.

An interview question that asks the respondent to make a selection

from a limited list of responses.

Advantages Closed-ended Open-ended

-Enhance consistency of response across respondents

- Allow more freedom of response

-Easier and faster to tabulate - Easier to construct

- More popular with respondents - Permit follow-up by interviewer

Disadvantages- May limit breadth of response - Tend to produce responses that

are consistent in length and content across respondents

- Take more time to construct - Both questions and responses subjects to misinterpretation

- Require more questions to cover the research topic

- Harder to tabulate and synthesize

Typical problems in wording questionsTYPICAL PROBLEMS IN WORDING QUESTIONS

Respondent Error• A classification of

sample bias resulting from some respondent action

Non-response -Total Nonresponse

Non-response-total nonresponse

• Not enough people respond or refuse to respond

• NONRESPONDENTS - People who refuse to cooperate

• NOT-AT-HOMES• SELF-SELECTION BIAS

especially in case of self-administered questionnaire. People respond to only those they like.

Item Nonresponse

- The respondent may not know the answer to a particular question, the respondent may find the questions embarrassing or irrelevant.

The END

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