Research Design: Blue print for conducting a study

May 15, 2013RG 701- Advance Research Methods

A plan, structure and strategy of

investigation so conceived as to obtain

answers to research question or problem.

What is Research Design?

Operationalizing the variables

Sample selection

Data collection

Analyzing results

Blueprint of research study

Once Research question has been finalized◦ Research Problem: decided what you want to

study

THEN

Need to determine how to conduct study Need to design your research

◦ Set of instructions for researcher to gather and analyze data

◦ Scheme of plan of actions for meeting the objectives

‘How’ of the research journey

To provide a plan in answering research question

Important Consideration:◦ To minimize the possible errors◦ To maximize the validity and reliability of data

In order to maximize the control over factors that could interfere with the validity of the findings

Purpose

1. Conceptualize an operational plan to undertake the various procedures and tasks required to complete your study

2. Control of variance: Ensure that these procedures are adequate to obtain valid, objective and accurate answers to the research question

Functions of a Research Design

Highlights the methods and tools that are used during research

process

Name ‘study design’

Detailed information regarding:

How the study will be conducted

Study population

Sample size

Type of data that will be collected

Identification of variables

Data collection means/method

Where interviews (if required) be conducted

Managing Ethical issues

Etc.

1. The researcher’s plan

Consistency, stability, or dependability of data

A research method should yield the same result, even if conducted twice or more

Reliability of Variables

Data need not only be reliable but valid as well

Validity refers to which extent an instrument is able to actually measure what it is supposed to measure

Validity of variables

Selection of a study design that will minimize the effects of

◦ extraneous variables influencing the independent variable

◦ chance or random error: due to random or chance variables –change in dependent variable due to respondent’s state of mode or ambiguity in the research instrument (ambiguous questions)

2. Theory of Causality

Study design in Quantitative Research

See Fig 8.1of text book

Classification based on:◦ Number of contacts◦ Reference period of study◦ Nature of the investigation

Types of Research Design

Number of Contacts

Three or moreTwoOne

X-sectional studiesBefore and after

studiesLongitudinal

studies

Study Design

Reference Period

Retrospective - Prospective

ProspectiveRetrospective

Study Design

Nature of Investigation

Semi-experimentalNon-experimentalExperimental

Study Design

Study Based on

Number of Contacts

Simple in design Also known as ‘one-shot’ or ‘status studies’ Best suited for finding out the prevalence of

a phenomenon, situation, problem, attitude or issue

Takes one time cross-section of a population Cross-sectional with regard to both

◦ Study population

◦ Time of investigation

Disadvantage:◦ Can not measure change

Cross-sectional Study Design

Also known as ‘Pre-test/post-test’ design Measures change Can be described as two sets of cross-sectional

data collection points on the same population in time

Change is measured by comparing the difference in the variable(s) before and after intervention

Disadvantages◦ Expensive and difficult◦ Measures total change including due to extraneous var.◦ Time lapse problems◦ Reactive effect of instrument/regression e

Before & After Studies

Before and after only measures change but not the trend…

Longitudinal studies determine the pattern in change in relation to time

Intervals may vary from study to study Considered as series of repetitive cross-

sectional studies

Longitudinal Studies

Study Based on

Reference Period

Investigates a phenomenon, situation, problem or issue that has happened in the past

conducted on the basis of:◦ data available for that period or ◦ respondents’ recall of the situation

Retrospective

Refers to the likely prevalence of a phenomenon, situation, problem or outcome in the future

Establishes the outcome of an event or what is likely to happen

Researcher must wait for an intervention to register its effects

Prospective

Focuses on past trends in a phenomenon and study it into the future

Part of data is collected retrospectively from existing records before the intervention in introduce

Influence of intervention is studied afterwards

Retrospective -Prospective

Study Based on

Nature of Investigation

Starting from cause to establish its effects

Introducing the intervention and monitor the change

Flexibility of controlling or manipulating the independent variable

Some commonly used experimental study designs:

◦ Before-and-after

◦ Control group design

◦ Double control design

◦ Comparative design

Experimental

Two population groups are selected for comparison (comparable in every respect except for the

intervention):

1. Experimental group

Receives/is exposed to the intervention

2. Control group

not exposed to the intervention

Chief objective of the control group is to quantify the impact of extraneous variables

Helps to ascertain the impact of the intervention only

Control group design

1. Make ‘Before’ observations on both groups (same time)

2. Experimental group is exposed to intervention3. Make ‘after’ observations on both groups4. Calculate difference in the ‘before’ and ‘after’

observations between the groups regarding dependent variable(s)

Continu….Control group design

Study population

Study population Study population

Study populationIntervention

I/var.

Experimental Group

Control Group

D/var. Y’e D/var. Y”e

D/var. Y’c D/var. Y”c

Exp G: Total Change in D/var. Ye = (Y”e-Y’e) = impact of (intervention ± extraneous var. ± chance var.)Cont. G: Total Change in D/var. Yc = (Y”c-Y’c) = impact of (extraneous var. ± chance var.)

Difference between Ex & Cont Groups equals to the ‘Impact of the Intervention’

Double Control Groups Two control groups To quantify the impact due to the research

instrument Exclude one control group from ‘before’

observation

The study the effectiveness of different interventions

The study population is divided into same number of groups as the number of interventions

Comparative design

Identical members from study population selected for study

Matched Control Experimental Design

Starting from effects to trace the cause

effects/outcomes --------- causation

Observation of a phenomenon and then establishing its cause

Non-experimental

Has properties of both experimental and non-experimental studies

Semi-experimental

Text book http://www.slideshare.net/ludymae/chapter-

7the-research-design

Rrferences