RESEARCH DESIGNS AND CLASSES IN THE

EXPERIMENTAL METHOD

CHAPTER 4 THE EXPERIMENTAL METHOD

PRE-EXPERIMENT

AL CLASS1. One-shot Case Study

2. One-group Pre-test Post-test Design

3. Intact Groups Design

QUASI-EXPERIMENTAL CLASS

1. Non-equivalent Control (or Comparison) Groups Design

2. Time Series Design3. Equivalent Time Samples

Design

EX POST FACTO CLASS1. Criterion Group Design*

2. Correlation Design

TRUE EXPERIMENT

AL CLASS1. Post-test Only Control

Group Design

2. Pre-test Post-test Control Group

Design*MAJOR DESIGNS AND CLASSES OF

RESEARCH DESIGNS IN EXPERIMENTAL

RESEARCH

(after Shavelson, 1981)

Design Does the design involve more than one group of subjects?

Does the design involve administering a treatment?

Does the design involve a randomly selected, randomly assigned control group to compare with the experimental group(s)?

Does the design involve some other kind of comparison group?

Is a pre-test given?

Is random selection used to constitute the sample?

Is random assignment used to constitute the groups?

One-shot Case Study

No Yes No No No No No

One-group Pre-test Post-test Design

No Yes No No Yes No No

Intact Groups Design

Yes Yes No Yes No No No

Non-equivalent Control (or Comparison) Groups Design

Yes Yes No Yes Yes No No

Time Series Design

No Yes No No Yes No No

Equivalent Time Samples Design

No Yes No No Yes No No

Criterion Group Design*

Yes No No Yes No Yes No

Correlation Design

No No No No No Yes No

Post-test Only Control Group Design

Yes Yes Yes No No Yes Yes

Pre-test Post-test Control Group Design*

Yes Yes Yes No Yes Yes Yes

RESEARCH DESIGN ISSUES

CHAPTER 4 THE EXPERIMENTAL METHOD

FROM SAMPLES TO POPULATIONS: THE

LOGIC OF INFERENTIAL STATISTICS

CHAPTER 4 THE EXPERIMENTAL METHOD

SAMPLE- a portion of a population, serving as a basis for estimates of the attribute of the whole population

POPULATION- a finite or infinite collection of items under consideration

Descriptive Statistics

Inferential Statistics

provides methods concerned with summarizing and describing numerical data. Uses tables, graphs, and charts that display data.

MeanStandard DeviationFrequency Polygon

concerns with generalizing information of making an inference about a population based only on a sample or portion observed

PAY-OFFS AND PITFALLS

CHAPTER 4 THE EXPERIMENTAL METHOD

Pitfalls

difficulty of controlling all the possible confounding variables associated with research on human subjectsClassroom research “entails a very large human

and institutional factors that can affect research design and outcomes in an unforeseen and unforeseeable ways”. (Rounds and Schachter, 1996)

more philosophical problemthe issue of subjectivity and objectivity

Pay-offs

a well-documented, highly codified approach to conducting a research with well-developed quality control procedures

an internationally recognized method of conducting a research

there are clear criteria for interpreting the outcomes

possibility of making comparisons across studies conducted at different sites

may enable researchers obtain grant money or get their reports published

CONCLUSION

CHAPTER 4 THE EXPERIMENTAL METHOD

SO WHAT?!The experimental method

has often been used in language classroom research, but with varied success, since it is so difficult to control all the possible confounding variables that can arise in the research with real people. It is, however, a valuable approach to understanding teaching and learning, and it has influenced many other approaches.