research designs for quantitative studies ppt

RESEARCH

DESIGNS FOR

QUANTITATIVE

STUDIES

Dr. Jayesh Patidarwww.drjayeshpatidar.blogspot.com

What is a research design?

A researcher’s overall plan for obtaining answers to the research questions or for testing the research hypotheses is referred to as the research design.

Aspects of research design

Intervention

Comparison

Controls of extraneous variables

Timing of data collection

Research sites and settings

Communication with the study participants

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The following questions would be addressed

What exactly is the intervention?

What are the procedures to be used for

both groups?

Who will receive the intervention and who

will not? How will each group be selected?

What is the dosage of the intervention?

INTERVENTION


INTERVENTION – Cont…

How long will the intervention be administered? And when will it begin?

Who will administer the intervention?

Will those administering the intervention are fully informed about the study? Will study participants be fully informed?

Under what conditions will the intervention be withdrawn or altered?


COMPARISONS

In a quantitative study, the researcher specifies the nature of the comparisons in advance, where as in a qualitative study, comparisons may suggest themselves during the course of data collection.

TYPES OF COMPARISONS IN RESEARCH STUDIES

Comparison between two or more groups

Comparison of a single group at two or more points in time

Comparison of a single group under different circumferences or experience

Comparison based on relative rankings

Comparison with samples from other studies


CONTROLS FOR EXTRANEOUS VARIABLES

The researcher must make decisions

about which extraneous variables to

control.

TIMING OF DATA COLLECTION

RESEARCH SITES & SETTINGS

COMMUNICATION WITH THE STUDY

PARTICIPANTS


Overview of Research Design Types

Structured versus flexible designs Eg. Quantitative study and qualitative study

Between –subjects and within –subjects designs Eg. Testing the efficacy of a drug

1. One group administered

one group do not administered Between subjects design

2. Same group before, after

treatment Within subjects design

The time dimension

There are four situations in which it might be appropriate to

design a study with multiple points of data collection.


1. Studying time related processes - Eg. Healing, earning, growth etc

2. Determining time sequences - Eg. Infertility results

in depression

3. Developing comparisons - Eg. Smoking and

lung

4. Enhancing research control - Eg. Two groups withalternative

interventions

Categorization of studies

• Cross sectional design

• Longitudinal design


Longitudinal design

Types– Trend studies

– Cohort studies

– Cross-sequential design (Control studies with a

cross –sectional approach)

– Panel studies

– Follow-up studies

Retrospective versus prospective

designs


Characteristics of good design

Appropriateness to the research question

Lack of bias

Precision

Power

Tips on designing research

Make a written list of the pros and cons of each

Balance a number of considerations, such as time, cost, ethical issues and the integrity of the study.

Anticipate alternative findings and consider whether design adjustments might affect the results.

Seek the advice of research experts in deciding the design

Write out a rationale for your choices one you have made your design decisions.


Experimental Research designs for quantitative studies

Characteristics of true experiments

Manipulation – Involves doing something to at least

one group of subjects

Control – Refers to a group of subjects without

any manipulation

Randomization – involves the Placement of subjects

in groups on a random basis

Research designs

Experimental designs

Quasi experimental designs

Non experimental designs


Types of experimental designs

Basic experimental design

Solomon four group design

Factorial design

Repeated measures design

Randomized clinical trials

Basic experimental design

Types

After only design or post test –only design (R-X-O)

Before after design or pretest –posttest design (R-O1 X O2)

(R-O1 – O2)


Solomon four group design

Group Date collection

Before After

Experimental –with

pretest

X X

Experimental –

without pretest

- X

Control-with pretest X X

Control-without

pretest

- X

This design prevents, the post test measures

getting affected not only by the treatment but

also by exposure to the pre-test9/30/2015 13www.drjayeshpatidar.blogspot.com

Factorial design

Types of stimulation Auditing tactile

A1 A2

A1 B1 A2 B1

A1 B2 A2 B2

A1 B3 A2 B3

15min B1 This design permits the testing

of multiple hypotheses in a

single experimental

Daily exposures

45m

B3

30min B2


Repeated measures design

Randomized clinical trials

Advantages and disadvantages of experimental studies.

Advantage – Confidence with which causal

relationships can be inferred

– Most powerful method available to scientists

Disadvantage – Hawthorne effect limitation

– Number of like characteristics of human

beings, finance etc


QUASI, EXPERIMENTAL RESEARCH

Quasi-Experimental designs

Non equivalent control group designs

Types

1.Non equivalent control group pre-test post –test design

(Quasi experimental)O1 X O2

O1 - O2

2. Non equivalent control group post test only design (Pre experimental)

X O

O


Time series designs

Types

1. Time series design (Quasi –experimental)

O1 O2 O3 O4 X O5 O6 O7 O8

2. Time series non-equivalent control group design (quasi-

experimental)

O1 O2 O3 O4 X O5 O6 O7 O8

O1 O2 O3 O4 - O5 O6 O7 O8

3. Time series with intensified treatment (quasi-experimental)

O1 O2 X O3 O4 X+1 O5 O6 X+2 O7 O8

4. Time series with withdrawn and reinstituted treatment

(quasi-experimental)

O1 O2 X O3 O4 (–X) O5 O6 X O7 O8


Advantages and disadvantages of the

quasi-experimental research

Advantages Feasibility

Generalizability some

extent

Practicality

Disadvantage Absent of control


Non Experimental Research

Reasons for under taking non-experimental

research in nursing o Human characteristics are inherently not subject

to experimental manipulation (eg. blood typepersonality etc) and the effects of thesecharacteristics on some phenomenon of interestcannot be studied experimentally.

o For ethical reasons.

o Not practical to conduct a true experiment

o Experimental design is not appropriate to some

research questions


Types of Non Experimental

Research

Ex post facto or correlational research

Descriptive research

1. Ex post facto design on correlational

research

Schematic diagram

Ex post facto design

Group A O

Group B O


Descriptive research

Purpose

- To observe, describe and document

aspects of situation as it naturally

occurs

- To serve as a starting point of for

hypothesis generation or theory

development.


Types

• Descriptive correlational study – No

control over the independent

variables

• Univariate descriptive studies – Not

focused on only one variable but to

describe the existing factors in terms

of frequency of occurrence


Advantages:

An efficient and effective means of collecting a large amount of data about a problem area

Short time only

No biophysiologic or other measures are needed

Has an intrinsic appeal for the solution of many practical problems.


Disadvantages:

Weak in its ability to reveal causal relationships

Susceptible to the possibility of faulty interpretation

Preexisting differences may be a plausible alternative explanation for any observed differences on the dependent variable of interest.


SURVEY RESEARCH

EVALUATION RESEARCH

NEEDS ASSESSMENT

OUT COMES RESEARCH

SECONDARY ANALYSIS

META –ANALYSIS

DELPHI SURVEYS

METHODOLOGIC RESEARCH

METHODOLOGIC RESEARCH

CONTENT ANALYSIS STUDIES

ADDITIONAL TYPES OF

QUANTITATIVE RESEARCH


research designs for quantitative studies ppt

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