Post on 08-Jan-2018
description
Types of Experimental Designs(Educational research)
True Experimental
Quasi-Experimental
Types of Experimental Designs
Simple True Experimental
Quasi-Experimental
Types
Randomized posttest control group design Randomized pretest-posttest control group
design
Randomized posttest control group design
R T PostR C Post
Randomized pretest-posttest control group design
R Pre T PostR Pre C Post
Makes it possible to ascertain that groups were equivalent at the beginning of the study.
Not necessary if: 1. Randomization was used2. Large sample size
Solomon four-group design
R Pre T PostR Pre C PostR T PostR C Post
Four groups are formed by random assignment ( R ) of participants, two groups are pretested ( O ) and two are not, one pretested and one unpretested group receive the experimental treatments ( X1, X2 ), each group is administered a posttest on the dependent variable, and posttest scores are compared to determine effectiveness of treatments
Types of Experimental Designs
Simple True Experimental
Quasi-Experimental
Characteristics of True Designs
Manipulation (treatment) Randomization Control group
Less control More real-world Program evaluation
Quasi-experimental Designs
One group posttest-only design One group pretest-posttest design Non-equivalent control group design Non-equivalent control group pretest-
posttest design Time series
Quasi-experimental Designs
One group posttest-only design One group pretest-posttest design Non-equivalent control group design Non-equivalent control group pretest-
posttest design Time series
Randomized posttest control only design
R T PostR C Post
One group posttest-only design (One shot study)
T Post
No control of IV threatsUse?
Quasi-experimental Designs
One shot study One group pretest-posttest design Non-equivalent control group design Non-equivalent control group pretest-
posttest design Time series
Randomized pretest-posttest control group design
R Pre T PostR Pre C Post
One group pretest-posttest design
Pre T Post
•History•Maturation•Testing•Instrumentation•Regression
Use control group
Quasi-experimental Designs
One shot study One group pretest-posttest design Non-equivalent control group design Non-equivalent control group pretest-
posttest design Time series
Randomized posttest control group design
R T PostR C Post
Non-equivalent control group design
(Static group comparison design)T PostC Post
•Selection bias
Quasi-experimental Designs
One shot study One group pretest-posttest design Non-equivalent control group design Non-equivalent control group pretest-
posttest design Time series
Randomized pretest-posttest control group design
R Pre T PostR Pre C Post
Non-equivalent control group pretest-posttest design
Pre T PostPre C Post
•Can check selection bias
Quasi-experimental Designs
One shot study One group pretest-posttest design Non-equivalent control group design Non-equivalent control group pretest-
posttest design Time series
Time series
Pre Pre Pre Pre T Post Post Post Post
…a single group is pretested ( O ) repeatedly until pretest scores are stable, exposed to a treatment ( X ) and, then, is repeatedly posttested ( O )