EXPERIMENTAL RESEARCHCHAPTER 13

Presented by :Nurul Ain binti Abd Manan 2013160689

Nor Zakiah binti Ismail 2013741249

Siti Khalijah binti Zainol 2013977165

Traditional type of research EXPERIMENTAL RESEARCH concerns relationships between

variables Purpose is to investigate cause-and-effect relationships

among variables• Experimental groups vs. control groups• Each group of participants receives a different treatment• Always involves manipulation of the independent variable

The researcher actually establishes different treatments and then studies their EFFECTS, results from this type of research are likely to lead to the most clear-cut interpretations

EXPERIMENTAL RESEARCH

STEPS IN EXPERIMENTAL RESEARCH

State the research problem Determine if experimental

methods apply Specify the independent

variable(s) Specify the dependent

variable(s) State the tentative hypotheses Determine measures to be used Pause to consider potential

success

Identify intervening (extraneous) variables

Formal statement of research hypotheses

Design the experiment Final estimate of potential

success Conduct the study as planned Analyze the collected data Prepare a research report

UNIQUENESSEXPERIMENTAL RESEARCH

Two ways in which EXPERIMENTAL RESEARCH differs from other educational research.

Researcher manipulate the independent variable :-

1. Decide the nature of the treatment

- to whom it is to be applied

- to what extent2. Enables researchers to go

- beyond description and prediction

- beyond the identification of relationship, to at least a partial determination of what causes them.

CHARACTERISTIC OF EXPERIMENTAL RESEARCH

CONTROL OF EXTRANEOUS VARIABLES

Researchers who conduct experimental studies try to control any and all the subject characteristics.

There are some common ways that had been used by researchers to minimize or eliminate threats

WAYS TO MINIMIZE OR ELIMINATE THREATSRandomization : assume the groups are equivalentHolding certain variable constant : eliminate the possible

effectsBuilding the variable into design : include as distinct groupMatching : pairs subjects matched to certain variablesUsing subjects as their own controls :compared the

performance Using analysis of covariance : equate groups

statistically on the basis of pretest or other variables

GROUP DESIGNS IN EXPERIMENTAL RESEARCH

Good designs control many of the various threats to internal validity (chapter 9) while poor designs control only a few.

The quality of an experiment depends on how well the various threats to internal validity are controlled.

POOR EXPERIMENTAL DESIGNS

One-Shot Case Study DesignIt does not provide for any comparison, so the

researcher cannot compare the treatment results (as measured by the attitude scale) with the same group before using the new textbook, or with those of another group using a different textbook.

The researcher knows nothing about what the group was like before using the text.

POOR EXPERIMENTAL DESIGNS

One-Group Pre test-Post test Design

This design is better than the one-shot case study (the researcher at least knows whether any change occur).

Nine uncontrolled-for threats (history, maturation, instrument decay, data collector characteristics, data collector bias, testing, statistical regression, attitude of subjects, and implementation).

The researcher would not know if any differences between pretest and posttest are due to the treatment or to one or more of these threats.

TRUE EXPERIMENTAL DESIGNS

The essential ingredient of a true experimental design is that subjects are randomly assigned to treatment groups.

Random assignment is a powerful technique for controlling the subject characteristics threat to internal validity

The randomized posttest-only control group design involves two groups formed by random assignment.

The randomized pretest-posttest control group design differs from the randomized posttest-only control group design only in the use of a pretest.

TRUE EXPERIMENTAL DESIGNS

TRUE EXPERIMENTAL DESIGNS

EVALUATING THE LIKELIHOOD OF A TRHREAT

The important consideration in planning an experimental study.

A number of possible threats may exist.The must ask question by the research is :

How likely is it that any particular threat exist in this study?

AID IN ASSESSING THE LIKELIHOODStep 1 : What specific factors either are

known to affect the dependent variable or may logically to be expected to affect this variable?

Step 2 : What is the likelihood of the comparison groups differing on each of these factors?

Step 3 : Evaluate the threats on the basis of how likely they are to have an effect, and plan to control for them.

THREATS TO INTERNAL VALIDITY

Subject characteristics

MortalityLocationInstrumentationTesting

HistoryMaturationAttitude of SubjectsRegressionImplementation

CONTROL OF EXPERIMENTAL TREATMENTS

Intended to improve the internal validity.It has advantages and disadvantages.The researcher control over the experimental

treatments- what, who, when and how of it.Researchers seldom have control in educational

research.

QUESTIONS

1)What is experimental research?

2)What are the uniqueness of experimental research?

3)How does the experimental research differ from other type of research?

4)What is random assignment, and what is the difference between random assignment and random selection?

5)How to describe poor experimental design?