Classroom Action Research

1. DEFINITION, PARADIGM, AND THEORI

Action research is classroom-based research conducted by teachers in order to reflect upon and evolve their teaching. It is a systematic, documented inquiry into one aspect of teaching and learning in a specific classroom. (Conducting Action Research In The Foreign Language Classroom Northeast Conference 1998 New York, Ny Anna Uhl Chamot Sarah Barnhardt Susan Dirstine Materials Contributor: Jennifer Kevorkian)

Action Research is a rather simple set of ideas and techniques that can introduce you to the power of systematic reflection on your practice. (How To Do Action research In Your Classroom Lessons From The Teachers Network Leadership Institute, By Frances Rust And Christopher Clark)

Penelitian tindakan merupakan tindakan yang menekankan kepada kegiatan (tindakan) dengan mengujicobakan suatu ide ke dalam praktek atau situasi nyata dalam skala mikro, yang diharapkan kegiatan tersebut mampu memperbaiki dan meningkatkan kualitas proses belajar mengajar. Jenis-jenis penelitian tindakan antara lain : (1) Penelitian Tindakan Diagnostik; (2) Penelitian Tindakan Partisipasi; (3) Penelitian Tindakan Empiris; (4) Penelitian Tindakan Eksperimental (Penelitian Tindakan, by Hartoto, M.Pd.)

Ada beberapa jenis action research, dua di antaranya adalah individual action research dan collaborative action research (CAR). Jadi CAR bisa berarti dua hal, yaitu classroom action research dan collaborative action research; dua-duanya merujuk pada hal yang sama. Action research lebih bertujuan untuk memperbaiki kinerja, sifatnya kontekstual dan hasilnya tidak untuk digeneralisasi. Namun demikian hasil action research dapat saja diterapkan oleh orang lain yang mempunyai latar yang mirip dengan yang dimiliki peneliti. (http://akhmadsudrajat.wordpress.com)

Classroom action research (CAR) adalah action research yang dilaksanakan oleh guru di dalam kelas. Action research pada hakikatnya merupakan rangkaian “ riset-tindakan-riset-tindakan- yang dilakukan secara siklik, dalam rangka memecahkan masalah, sampai masalah itu terpecahkan. (http://akhmadsudrajat.wordpress.com)

Penelitian Tindakan Kelas (PTK) atau disebut juga dengan Classroom Action Research (CAR) adalah penelitian tindakan yang dilakukan dengan tujuan memperbaiki mutu praktik pembelajaran di kelas. Tujuan utama PTK adalah untuk memecahkan permasalahan nyata yang terjadi di kelas dan meningkatkan kegiatan nyata Guru dalam pengembangan profesionalnya. (Penelitian Tindakan Kelas (Classroom Action Research) Salah Satu Bentuk Karya Tulis Ilmiah Untuk Pengembangan Profesi Guru, Oleh Susanto, S.H.I )

Our basic assumption is that you have within you the power to meet all the challenges of the teaching profession. Furthermore, you can meet these challenges without wearing yourself down to a nub. The only theories involved are the ideas that you already use to make sense of your

experience. (How To Do Action Research In Your Classroom Lessons From The Teachers Network Leadership Institute, By Frances Rust And Christopher Clark)

2. THE SYNTHESIS

Well, after reading the material above,

Based on what we have read, Classroom Action Research has some components

So, Classroom Action Research is a research of an action happens in a classroom (educational situation) specifically about the problems during the teaching activities. It is related to the teacher as the subject of teaching process. The teacher can do this research by him/herself. But it also can be a collaborative one. The researcher's consideration is the teaching process' reflection then finding some problems so that can be solved by applying other strategies.

All of parts happen in a cycle. It means, after applying the new strategy then he/she can reflect it again then finding another strategy. By this research, the researcher can find the better way of teaching for repairing the teaching strategy and also improving his/her skill. Of course, for the teacher, it can develop his/her professionalism.

3. THE REVIEW

A. The Concept of Classroom Action Research

Classroom Action Research is a research that is done to find the problems occur in the teaching and learning process so there will be the solution for repairing the educational system.

The problems taken by the researcher should be an apprehensive one and the researcher has the commitment to solve them. In doing classroom action research, the researcher should be consistent in paying attention to the ethics procedure that is related to his/her job.

Although a class is in the teacher's responsibility's coverage, but in doing the research he/she has to use classroom exceeding perspective, that is the problems are not just considered as a class' context or a certain lesson (micro scale), but they have to be considered as a school's perspective mission entirely (macro scale).

CAR uses action research's main concept that consists of 4 components :

1) Planning

2) Acting

3) Observing

4) Reflecting

Those four components are related each ther as a cylce.

is the first step the researcher has to do before doing something. The planning is expected to be futuristic and flexible to face some non-anticipated effects. By the planning, we can prepare to handle the troubles early. By a good planning, a researcher can be easier to face some problems and it will be more effective in doing research.

The Planning's Principle

Those five principles should be considered in the planning step.

is an applying of the planning. It can be a teaching method applying that has a purpose to repair or complete a certain model.

That action can be applied by the persons who are involved in the applying a teaching method which the result also will be sude for completing in doing assignment.

is used to see and and capture some influences caused by a classroom action. This observation's result is a basic of doing reflection so that the research should be able to show the real situation. In the observation, the researcher should take a note of the process of action, the action's effetcs, environment, and some troubles.

consists of : analysis, synthesis, interpretation, explanation, and conclusion.

The reflection's result is having revision of the planning which has been done, and it can be used for repairing the teacher's performance in the future. Thereby, the action research can't be held in only one meeting because it needs more time to do the reflection's result as a planning for the cycle after.

B. The Types of Classroom Action research :

1) Diagnostic type

The research that leads the researcher to an action because there is a problem happens. e.g. there is a conflict between students in a class, etc.

2) Participant type

The research which the researcher is involved directly from start till final.

3) Empirical type

The research is done by a planning to take a note of the process and evaluate the process out of the class. So, the researcher should collaborate with the teacher who does the classroom action.

4) Experimental type

The research is done as the way of applying some techniques, methods, or strategies in the teaching and learning process effectively and efficiently.

C. Characteristics

The characteristics of Classroom Action Research are:

It is based on the situation and related to the diagnosis and a problem solving in a certain context.

It can be participatory –if the research is done in a group- so each person takes a part in the process of research.

It can be self evaluative. The researcher doing evaluation continuously to improve his/her professionalism.

The procedure of action research is on the spot that is designed to handle the concrete problem happens in that place.

Its result can be immediately applied and long range

It is supple and adaptive

It more emphasizes the process than the method.

It is done to solve the chronic problem, not the new identified one

The classroom action researcher is ideally the person who really knows about the problems happen. Therefore, a teacher can be a doctor who will cure a chronic ill through the best recipe.

It is done in a cycle – as written in the "planning principle" above –. In every new cycle, ideally there will be significant difference with the previous cycle. It means the cycle in the previous research is not effective enough to solve the problem faced by the researcher.

The reflection's result of the previous cycle is the basic for the next cycle for making re-planning.

D. Purpose and Significance

Generally, the purposes of Classroom Action Research are:

(1) Improving the quality, process, and result of the teaching and learning process in a school.

(2) Helping the teacher and another educational staff to solve the educational problem.

(3) Growing the teacher and another educational staff's professionalism.

(4) Improving the academic culture in the school environment to create an active attitude in repairing the educational quality continuously.

In a graphic, I divide them into two groups of purposes

The significances of Classroom Action Research are :

a. Educational innovation

In the educational innovation, a teacher needs to try changing, developing, and improving his/her teaching style so that he/she can get a new teaching style which is appropriate for the students.

b.

c. Curriculum development

For the curriculum development, CAR will be very helpful if it is used as one of the sources. The process will be influenced by some related ideas about education, knowledge, and teaching. CAR can help the teacher to understand more empirically, not only teoritically.

d. Teacher's professionalism development

A professional teacher will not be bored to do revolution in the teaching process based on the classroom condition. CAR is one of medias used by the teacher to understand what happens in a class. Then he/she begins to repair it professisonally. A professional teacher needs to see and examine the process happens in a class critically . by examining his/her own teaching process, then he/she does reflection and repairing. At last, the teacher will be more professional.

Sources :

- Conducting Action Research In The Foreign Language Classroom Northeast Conference 1998 New York, Ny Anna Uhl Chamot Sarah Barnhardt Susan Dirstine Materials Contributor: Jennifer Kevorkian

- How To Do Action research In Your Classroom Lessons From The Teachers Network Leadership Institute, By Frances Rust And Christopher Clark

- http://akhmadsudrajat.wordpress.com

- Penelitian Tindakan, by Hartoto, M.Pd.

- Penelitian Tindakan Kelas (Classroom Action Research) Salah Satu Bentuk Karya Tulis Ilmiah Untuk Pengembangan Profesi Guru, Oleh Susanto, S.H.I

An Introduction to Action Research

I feel that we need to make a greater effort to involve teachers in Action Research. Teachers already know much about teaching--more than many of us do. But many are waiting to be invited to participate in research studies in which they examine students' preconceptions, or effective teaching strategies. It is through joint research studies that science instruction in the schools will improve, and we need to make a great effort in this regard.

Dorothy GabelPresidential Address

National Association for Research in Science Teaching (NARST)San Francisco, April 24, 1995

Action Research (AR) represents a growing field of educational research whose chief identifying characteristic is the recognition of the pragmatic requirements of educational practitioners for organized reflective inquiry into classroom instruction. AR is an process designed to empower all participants in the educational process (students, instructors and other parties) with the means to improve the practices conducted within the educational experience (Hopkins, 1993). All participants were knowing, active members of the research process.

Action research has been described as an informal, qualitative, formative, subjective, interpretive, reflective and experiential model of inquiry in which all individuals involved in the study are knowing and contributing participants (Hopkins, 1993). Action research has the primary intent of providing a framework for qualitative investigations by teachers and researchers in complex working classroom situations.

Some of the most widely accepted definitions of Action Research include following:

[Action Research] ...aims to contribute both to the practical concerns of people in an immediate problematic situation and to the goals of social science by joint collaboration within a mutually acceptable ethical framework. - Rapoport (cited in Hopkins, 1985)

Action Research is a form of self-reflective enquiry undertaken by participants in social (including educational) situations in order to improve the rationality and justice of (a) their own social or educational practices, (b) their understanding of these practices, and (c) the situations in which the practices are carried out. It is most rationally empowering when undertaken by participants collaboratively...sometimes in cooperation with outsiders. - Kemmis (cited in Hopkins, 1985)

[Action Research] ...is the systematic study of attempts to improve educational practise by groups of participants by means of their own practical actions and by means of their own reflection upon the effects of those actions. - Ebbutt (cited in Hopkins, 1985)

The action research framework is most appropriate for participants who recognize the existence of shortcomings in their educational activities and who would like to adopt some initial stance in regard to the problem, formulate a plan, carry out an intervention, evaluate the outcomes and develop further strategies in an iterative fashion (Hopkins, 1993). In short, action research is characterized by those constraints and strengths given a research methodology intended to be a workable technique for working classroom teachers.

Action Research Design

The essentials of action research design are considered by Elliott (in Hopkins, 1993) as per the following characteristic cycle:

Initially an exploratory stance is adopted, where an understanding of a problem is developed and plans are made for some form of interventionary strategy. (The Reconnaissance & General Plan .)

Then the intervention is carried out . (The Action in Action Research) During and around the time of the intervention, pertinent observations are

collected in various forms. (Monitoring the implementation by Observation. )

The new interventional strategies are carried out, and the cyclic process repeats, continuing until a sufficient understanding of (or implement able solution for) the problem is achieved (Reflection and Revision).

The protocol is iterative or cyclical in nature and is intended to foster deeper understanding of a given situation, starting with conceptualizing and particularizing the problem and moving through several interventions and evaluations. A representation of an AR protocol by Kemmis is provided in Figure 1.

Figure 1: Action Research Protocol after Kemmis (cited in Hopkins, 1985)

Figure 1 clearly displays the iterative nature of AR along with the major steps of planning, action, observation and reflection before revising the plan . This may be thought of as similar in nature to the numerical computing technique known as successive approximation - the idea is to close in upon a final goal or outcome by repeated iterations.

Later protocols reflect changes in the goal as determined via experience during the reflections of earlier iterations of AR. For instance, Figure 2 reflects the evolution of the general idea or main topic of interest throughout the process.

Figure 2: Action Research after Elliott (cited in Hopkins, 1985)

Elliott's model emphasizes constant evolution and redefinition of the original goal through a series of reconnaissances recurring every cycle. The reconnaissance necessarily includes some degree of analysis. This design permits much greater flexibility, and seeks to "...recapture some of the 'messiness' which the Kemmis version tends to gloss [over] " (Hopkins, 1985). Ebbutt further illustrates the evolution of the overall plan through a spiral analogy, as described in Figure 3.

Figure 3: Action Research Protocol after Ebbutt (cited in Hopkins, 1985)

The Role of Communication

Another distinguishing characteristic of Action Research is the degree of empowerment given to all participants. Involvement is of a knowing nature, with no hidden controls or preemption of direction by the researcher. All participants negotiate meaning from the data and contribute to the selection of interventionary strategies, including the university researchers, the teachers and the students.

The Role of Reflection

Another distinguishing characteristic of action research is the degree of empowerment given to all participants. Involvement is of a knowing nature, with no hidden controls or preemption of direction by the researcher. All participants including the university researchers, the teachers and the students negotiate meaning from the data and contribute to the selection of interventionary strategies.

Elliott (in Kemmis & McTaggart, 1990b) considers the need for communication between all participants to be of paramount importance:

Since action research looks at a problem from the point of view of those involved it can only be validated in unconstrained dialogue with them. ...Since action research involves unconstrained dialogue between "researcher" (whether he be an outsider or teacher/researcher) and the participants, there must be free information flow between them. (p. 122)

Perhaps the key component involved in action research is the notion of praxis. Action research is intended to be the reflective counterpart of practical diagnosis (Elliott, 1978). Schon (1983) describes the use of reflection to generate models from a body of previous knowledge. These models are used to re-frame a problem;

then experiments are performed to bring about outcomes which are subjected to further analysis. This model (called reflection-in-action) frames means and ends interdependently and recognizes that there is little or no separation of research from practice, little or no separation of knowing and doing. Schon's model of reflection-in-action compliments the iterative and investigative natures of action research.

Dan MacIsaac, 1996 (http://www.physics.nau.edu/~danmac)

References:

Gabel, D. (1995). NARST President's Speech. Presented at the annual meeting of the National Association for Research in Science Teaching, San Francisco, CA.

Hopkins, D. (1985). A teacher's guide to classroom research. Philadelphia: Open University Press.

Kemmis, S., & McTaggart, R. (Eds.). (1990b). The action research reader. Victoria: Deakin University.

Schon, D. A. (1983). The reflective practitioner : How professionals think in action. New York: Basic Books.

EXPERIMENTAL DESIGNS  FOR RESEARCH

Causality Experimental Designs Control Group Pre-test/Post-test Design Threats to Internal Validity Threats to External Validity Post-Test only Control Group Design

CAUSALITYTo establish whether two variables are causally related, that is, whether a change in the independent variable X results in a change in the dependent variable Y, you must establish:

1) time order--The cause must have occurred before the effect;

2) co-variation (statistical association)-- Changes in the value of the independent variable must be accompanied by changes in the value of the dependent variable;

3) rationale-- There must be a logical and compelling explanation for why these two variables are related;

4) non-spuriousness-- It must be established that the independent variable X, and only X, was the cause of changes in the dependent variable Y; rival explanations must be ruled out.

To establish causality, one must use an experimental or quasi-experimental design. Note that it is never possible to prove causality, but only to show to what degree it is probable.

EXPERIMENTAL DESIGNS

True experimental designs include:

Pre-test/Post-test control group design

Solomon Four-Group design

Post-test only control group design

Pre-test/Post-test control group design This is also called the classic controlled experimental design, and the randomized pre-test/post-test design because it:

1) Controls the assignment of subjects to experimental (treatment) and control groups through the use of a table of random numbers.

This procedure guarantees that all subjects have the same change of being in the experimental or control group. Because of strict random assignment of subjects, it is assumed that the two groups are equivalent on all important dimensions and that there are no systematic differences between the two groups. Researchers may substitute matching for random assignment. Subjects in the two groups are matched on a list of characteristics that might affect the outcome of the research (e.g., sex, race, income). This may be cheaper but matching on more than 3 or 4 characteristics is very difficult. And if the researcher does not know which characteristics to match on, this compromises internal validity.

2) Controls the timing of the independent variable (treatment) and which group is exposed to it.

Both group experience the same conditions, with the exception of the experimental group, which receives the influence of the independent variable (treatment) in addition to the shared conditions of the two groups.

3) Controls all other conditions under which the experiment takes place.

Nothing but the intervention of the independent (treatment) variable is assumed to produce the observed changes in the values of the dependent variable.

The steps in the classic controlled experiment are:

1) randomly assign subjects to treatment or control groups;

2) administer the pre-test to all subjects in both groups;

3) ensure that both groups experience the same conditions except that in addition the experimental group experiences the treatment;

4) administer the post-test to all subjects in both groups;

5) assess the amount of change on the value of the dependent variable from the pre-test to the post-test for each group separately.

These steps are diagramed as follows:

    R     O1     X     O2     R     O1             O2

This diagram can be expanded upon as in the following table:  

Scientific Random Assignment of Subjects to:

1st observation (measurement) of the dependent variable O1 = Pre-test

Exposure to the Treatment (X) (independent variable)

2nd observation (measurement) of the dependent variable O2 = Post-test

Experimental GroupExperimental Group's average score on the dependent variable

XExperimental Group's average score on the dependent variable

Control GroupControl Group's average score on the dependent variable

Control Group's average score on the dependent variable

The difference in the control group's score from the pre-test to the post-test indicates the change in the value of the dependent variable that could be expected to occur without exposure to the treatment (independent) variable X.

Control group    -    control group     =    control group difference pre-test score        post-test score            on the dependent variable

The difference in the experimental group's score from the pre-test to the post-test indicates the change in the value of the dependent variable that could be expected to occur with exposure to the treatment (independent) variable X.

Experimental group    -    experimental group     =    experimental group difference pre-test score                post-test score                    on the dependent variable

The difference between the change in the experimental group and the change in the control group is the amount of change in the value of the dependent variable that can be attributed solely to the influence of the independent (treatment) variable X.

Control group difference    -    experimental group difference    =    difference attributable to X

This can be illustrated by the following experiment to see whether participation in small group discussions would improve medical students' ability to respond to emotional needs of patients:  

Scientific Random Assignment of Medical Students to:

How many times did students use emotional words to describe patients

Exposure to the Treatment (X) (independent variable)

How many times did students use emotional words to describe patients

Small group discussions (experimental group)

Average of .68 times per student in 3 case studies

Attended small group discussions plus regular course work

Average of 2.02 times per student in 3 case studies

Control GroupAverage of .89 times per student in 3 case studies

Regular course work only

Average of 1.13 times per student in 3 case studies

The control group used emotional words an average of .89 times per student (in three case studies) on the pre-test and an average of 1.13 times per student (in three case studies) on the post-test.  The difference in the control group's score from the pre-test to the post-test is +.24 times per student.  This indicates the change in using emotional words that could be expected to occur with regular course work only.

The experimental group used emotional words an average of .68 times per student (in three case studies) on the pre-test and an average of 2.02 times per student (in three case studies) on the post-test.  The difference in the experimental group's score from the pre-test to the post-test is +1.34 times per student.  The experimental group's score from the pre-test to the post-test indicates the change in using emotional words that could be expected to occur with regular course work plus the small group discussions.

The difference between the change in the experimental group (+1.34) and the change in the control group (+.24) is +1.10.  This is the amount of change in using emotional words that can be attributed solely to the influence of the small group discussions.

The controlled or true experimental design allows the researcher to control for threats to the internal and external validity of the study.  Threats to internal validity compromise the researcher's ability to say whether a relationships exists between the independent and dependent variables.  Threats to external validity compromise the researcher's ability to say whether this study's findings are applicable to any other groups.

Controlling for Threats to Internal Validity1) History: did some other current event effect the change in the dependent variable? No, because both groups experienced the same current events.

2) Maturation:  were changes in the dependent variable due to normal developmental processes?  No, because both groups experienced the same developmental processes.

3) Statistical Regression:  did subjects come from low or high performing groups?  Differences between the two groups that could influence the dependent variable would be controlled for as subjects were generally equivalent at the beginning of the research.

4) Selection:  were the subjects self-selected into experimental and control groups, which could affect the dependent variable?  No, the subjects were assigned by strict random selection and all had equal chance of getting the treatment or control condition.

5) Experimental Mortality:  did some subjects drop out?  did this affect the results?  About the same number of students made it through the entire study in both the experimental and control groups, so there appears to be no bias.

6) Testing:  Did the pre-test affect the scores on the post-test?  Both groups got a pre-test; but a pre-test may have made the experimental group more sensitive to the treatment.

7) Instrumentation:  Did the measurement method change during the research?  The measurement method and instruments did not change.

8) Design contamination:  did the control group find out about the experimental treatment?  did either group have a reason to want to make the research succeed or fail?  The researcher must do some qualitative investigation to find out if there was design contamination.  

Controlling for Threats to External Validity1) Unique program features: There may have been an unusually motivated set of facilitators for the small group discussions.

2)  Effects of Selection:  Probably applicable to other medical students.

3) Effects of Setting:  Medical schools have their own cultures; doubtful if this would be applicable to other types of students.

4) Effects of History:  No information given

5) Effects of Testing:  No information given

6)  Reactive effects of experimental arrangements:  It would be best to replicate the results in other medical schools.  

Post-Test Only Control Group Design This design follows all the same steps as the classic pre-test/post-test design except that it omits the pre-test. There are many situations where a pre-test is impossible because the participants have already been exposed to the treatment, or it would be too expensive or too time-consuming. For large enough groups, this design can control for most of the same threats to internal and external validity as the classic controlled experimental design. For example, it eliminates the threat to internal validity of pre-testing by eliminating the pre-test. It may

also decrease the problem of experimental mortality by shortening the length of the study (no pre-test).

For small groups, however, a pre-test is necessary.  Also, a pre-test is necessary if the researcher wants to determine the exact amount of change attributable to the independent variable alone. Public administrators would like to be able to use experimental designs for policy and program evaluation.  Did a regional economic development policy bring more business to the economically depressed region?  Did the Women-Infants-and-Children (WIC) program lower the rate of malnutrition in young children?  

Unfortunately, it is difficult for public administrators to meet the requirements of the classic controlled experimental design.

-It is difficult to conduct program evaluations in a laboratory, where other influences can be controlled.

-It is difficult to achieve random assignment, due to political and ethical concerns.

-Policies may not be specific as to what changes they intend to produce.

-Often funds or other resources for a large-scale research project are lacking.

-Decision makers often operate on short time frames and cannot wait for an experimental study to run its course.

-Research is not always begun before a program is implemented, and therefore cannot take measurements of the "before" condition.

-Programs are not always implemented all at once, but rather gradually, over time, which may diminish their effects.

-Programs may not be implemented as originally intended, or may not produce the effects that researchers are looking for.

-Small treatments with modest goals are more amenable to a controlled experimental design than large scale social programs with ambitious goals.

EXPERIMENTAL RESEARCH

The Uniqueness of Experimental Research

Experimental research is unique in that it is the only type of research that directly attempts to influence a particular variable, and it is the only type that, when used properly, can really test hypotheses about cause and effect relationships. Experimental designs are some of the strongest available for educational researchers to use in determining cause and effect.

Essential Characteristics of Experimental Research

Experiments differ from other types of research in two basic ways-comparisons of treatments and the direct manipulation of one or more independent variables by the researcher.

Randomization

Random assignment is an important ingredient in the best kinds of experiments. It means that every individual who is participating in the experiment has an equal chance of being assigned to any of the experimental or control conditions that are being compared.

Control of Extraneous Variables

The researcher in an experimental study has an opportunity to exercise far more control than in most other forms of research.

Some of the most common ways to control for the possibility of differential subject characteristics (in the various groups being compared) are randomization, holding certain variables constant, building the variable into the design, matching, using subjects as their own controls, and using analysis of the covariance.

Weak Experimental Designs

Three weak designs that are occasionally used in experimental research are the one shot case study design, the one group pretest-posttest design, and the static group comparison design. They are considered weak because they do not have built in controls for threats to internal validity.

In a one shot case study, a single group is exposed to a treatment or event, and its effects are assessed.

In the one group pretest posttest design, a single group is measured or observed both before and after exposure to a treatment.

In the static group comparison design, two intact groups receive different treatments.

True Experimental Designs

The essential ingredient of a true experiment is random assignment of subjects to treatment groups.

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

As before, the symbol X represents exposure to the treatment and O refers to the measurement of the dependent variable. R represents the random assignment of individuals to groups. C now represents the control group.

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

The randomized Solomon four group design involves random assignment of subjects to four groups, with two being pretested and two not.

Matching

To increase the likelihood that groups of subjects will be equivalent, pairs of subjects may be matched on certain variables. The members of the matched groups are then assigned to the experimental and control groups.

Matching may be either mechanical or statistical.

Mechanical matching is a process of pairing two persons whose scores on a particular variable are similar.

Two difficulties with mechanical matching are that it is very difficult to match on more than two or three variables, and that in order to match, some subjects must be eliminated from the study when no matches can be found.

Statistical matching does not necessitate a loss of subjects.

Quasi-Experimental Designs

The matching only design differs from random assignment with matching only in that random assignment is not used.

In a counterbalanced design, all groups are exposed to all treatments, but in a different order.

A time series design involves repeated measurements or observations over time, both before and after treatment.

Factorial Designs

Factorial designs extend the number of relationships that may be examined in an experimental study.