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Flashcards in Experimental Research Deck (18)
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Experimental research purpose

provide structure for evaluating cause-and-effect relationship between dependent and independent variables.


Experimental Design:
by degree of experimental control

True-experiment vs Quasi-experimental designs


Experimental Design:
by how subjects are assigned to groups

Between-subjects and Within-subjects designs


True experimental design

subjects randomly assigned to at least 2 comparison groups


Quasi-experimental design

does not meet requirements of true experiment

lacks random assignment, comparison groups, or both

used when true experimental design not feasible

accommodates for limitations in natural settings.


Between subjects design

subjects randomly assigned to independent groups

completely randomized


Within subjects design

subjects act as their own control

repeated measures design


Single factor design

structures the investigation of one independent variable

easy to develop

can't account for simultaneous interactions of several variables


mult-facctor design

incorporates two or more independent variables.

n-way design, a x b design, etc


Pretest-posttest control group design

basic structure of RCT

compares 2 or more groups that are formed by random assignment


changes from pretest to posttest that appear in experimental group but not control group:

can be reasonably attributed to the intervention


considered the scientific standard in clinical research for establishing cause-and-effect relationship

Pretest-Posttest Control Group Design


Posttest only control group design

identical to pretest-posttest but with no pretest administered to either group.

Used when pretest is impractical or reactive


Repeated measures design

ability to control potential influence of individual differences

uses subjects as their own control

potential for practice effects and carryover effects


When is a Repeated measures design used?

only used when outcome measure will revert back to baseline between interventions and pt problem will remain stable throughout study period


Crossover design

half of the subjects receive treatment A followed by treatment B. Other half B then A

subgroups randomly assigned into one of the sequences


When would you use a crossover design?

When patient's condition will not change over time

not a reasonable approach when treatment effects are slow

washout period is essential


Mixed design

has within-subject factors and between-subject factors

within: repeated and crossover

between: single factor, multifactor, pretest-posttest, posttest only