Quantitative Research Design

Backdrop to Multivariate Analysis

Quantitative Research Process

Research Objectives Background of the Problem Research Questions Hypotheses Method Data Analysis Discussions and Implications Limitations

Research Proposal

A written statement of the research design

Including the purpose of the study, definition of the problem, research methodology and details of the procedures

Sampling

Sampling terminology Sample Population Population element Census

Why sample? Pragmatic reasons Accurate and reliable results

Probability versus Nonprobability Sampling

Probability sampling Simple random sampling Systematic sampling Stratified sampling Proportional versus disproportional strata Cluster sampling Multistage area sampling

Nonprobability sampling Convenience sampling Judgment sampling (purposive sampling) Quota sampling Snowball sampling

Sample Size

Confidence level

Variables

Categorical (classificatory) variable Continuous variable Dummy variable Independent variable Dependent variable

Tips for Questionnaire Design Two basic criteria

Relevance Accuracy

Opened-ended v.s. fixed-alternative questions Types of fixed-alternative questions (mutually

exclusive) Dichotomous-alternative question Determinant-choice question Frequency-determination question Checklist question

The Art of Asking Questions Avoid complexity: use simple language Avoid leading and loaded questions

Counterbiasing statement Split-ballot technique

Avoid ambiguity: be as specific as possible Avoid double-barreled items Avoid making assumptions Avoid burdensome questions that may tax

the respondent’s memory

Some Issues about Questionnaire Design

Order Bias Funnel technique Anchoring effect Filter question Pivot question

Best Layout Multiple-grid question

Pre-testing and Revising

Survey Research

Advantages of survey research: Quick Inexpensive Efficient Accurate

Survey Research

Total Error

Random sampling

error

Systematic error

Respondent error

Administrator error

Nonresponse error

Response bias

Deliberate falsification

Unconscious misrepresentation

Acquiescence bias

Extremity bias

Interviewer bias

Auspices bias

Social desirability

biasData processing error

Sample selection error

Interviewer error

Interviewer cheating

Experimental Research A research investigation in which

conditions are controlled so that an independent variable(s) can be manipulated to test a hypothesis about a dependent variable.

Allows evaluation of causal relationships among variables while all other variables are eliminated or controlled.

Basic Issues in Experimental Design

Manipulation of the independent variable Experimental treatments Experimental and control groups Experimental treatment levels More than one independent variable Selection and measurement of the

dependent variable Demand characteristics Debriefing (ethical issue)

Experimental Validity External validity (generalizability) Internal validity

The ability of an experiment to answer the question of whether an experimental treatment was the sole cause of changes in a dependent variable or whether the experimental manipulation did what it was supposed to do.

History Maturation Testing Instrumentation Selection Mortality

Measurement– types of scales Nominal scale

Frequency in each category Percentage in each category

Ordinal scale (rank order) Median Range Percentile ranking

Interval scale (rank order in equal intervals) Mean Standard deviation Variance

Ratio scale (arithmetic operations on actual quantities) Geometric mean Coefficient of variation

Reliability

Old Rifle New Rifle New Rifle Sunglare

(low reliability) (high reliability) (reliable but not valid)

Reliability Analysis

Cronbach’s alpha cofficeint (Cronbach, 1951) Refer to the applicability of obtained scored

as an estimate of “true” scores if all possible tests or all possible scores were available

What is acceptable reliability? 0.85 or higher Depends on the numbers of item and the situation