Please enable JavaScript.
Coggle requires JavaScript to display documents.
Experimental Research, Nonequivalent Designs, Hybrid Experimental Designs …
Experimental Research
Two-Group Experimental Designs - involves one treatment group & one control group; ideally suited for testing the effects of a single independent variable that can be manipulated
-
-
-
Factorial Design - enables researcher to examine not only the individual effect of each treatment on the dependent variables, but also their joint effect (interaction effect); requires manipulation of two or more independent variables.
Main Effect - exists if the dependent variable shows a significant difference between multiple levels of one factor, at all levels of other factors.
Interaction Effect - exists when the effect of differences in one factor depends upon the level of a second factor.
2 Categories of Experimental Research: 1). true experimental design; 2). quasi-experimental designs - both designs require treatment manipulation, but true experiments also require random assignment & quasi-experiments do not.
Quasi Experimental Designs - are almost identical to true experimental designs, but lacking random assignment.
Nonequivalent Groups Design - the quasi-equivalent version of pretest-posttest control group design.
Nonequivalent Switched Replication Design - the quasi-experimental version of switched replication design.
Internal Validity (Causality) - the unique strength of experimental research; has the ability to link cause & effect through treatment manipulation, while controlling for the spurious (false or fake) effect of extraneous variable.
-
Laboratory Experiments - conducted in a laboratory (artificial) setting; tend to be high in internal validity.
Field Experiments - conducted in field settings such as in a real organization; high in both internal and external validity; relatively rare because of the difficulties associated with manipulating treatments and controlling for extraneous effects in a field setting.
Treatment Group - in experimental research, some subjects are administered one or more experimental stimulus (treatment); multiple levels of experimental stimulus administered & there could be more than one treatment group.
Control Group - in experimental research, some subjects are not given a stimulus.
Treatment Manipulation - helps control for the "cause" in cause-effect relationships; must be checked using pretest measures (measurements conducted before the treatment is administered) and pilot tests prior to the experimental study. Posttest measures are conducted after the treatment;
Random Selection - process of randomly drawing a sample from a population or a sampling frame; typically used in survey research; assures that each unit in the population has a positive chance of being selected into the sample; related to sampling, so more closely related to external validity (generalizability) of findings.
Random Assignment - process of randomly assigning subjects to experimental or control groups; standard practice in true experimental research to ensure treatment groups are similar (equivalent) to each other and to the control group prior to treatment administration; related to design, so more closely related to internal validity.
-
History Threat - possibility that observed effects (dependent variables) are caused by extraneous or historical events rather than the experimental treatment.
Maturation Threat - possibility that observed effects are caused by natural maturation of subjects rather than the experimental treatment.
Testing Threat - threat in pre-post designs where subject's posttest responses are conditioned by their pretest responses.
Instrumentation Threat - occurs in pre-post designs, refers to the possibility that the difference between pretest and posttest scores is not due to the remedial math program, but due to the changes in the administered test.
Mortality Threat - refers to the possibility that subjects may be dropping out of the study at differential rates between the treatment and control groups due to a systematic reason.
Regression Threat (regression to the mean) - refers to the statistical tendency of a group's overall performance on a measure during a posttest to regress toward the mean of that measure rather than in the anticipated direction.
-
Nonequivalent Designs
Regression-Discontinuity (RD) Design - subjects are assigned to treatment or control group based on a cutoff score on a preprogram measure.
Proxy Pretest Design - looks very similar to the standard NEGD (pretest-posttest) design, but the pretest score is collected after the treatment is administered.
Separate Pretest-Posttest Samples Design - useful if it is not possible to collect pretest and posttest data from the same subjects for some reason.
Nonequivalent Dependent Variable (NEDV) Design - a single-group pre-post quasi-experimental design with 2 outcome measures; Pattern Matching NEDV Design - employs multiple outcome variables and a theory that explains how each variable will be affected by the treatment.
Hybrid Experimental Designs - those that are formed by combining features of more established designs.
Randomized Block Design - a variation of the posttest-only or pretest-posttest control group design where the subject population can be grouped into relatively homogeneous subgroups (blocks) within which the experiment is replicated.
Solomon Four-Group Design - the sample is divided into two treatment groups and two control groups; one treatment group and one control group receive the pretest and the other two groups do not.
Switched Replication Design - this is a two-group design implemented in two phases with three waves of measurement; the treatment group in the 1st phase serves as the control group in the 2nd phase, and the control group in the 1st phase becomes the treatment group in the 2nd phase.