Ch.7: Group Research Designs Flashcards
Group Experimental Designs
compare groups of individuals to describe, compare, or relate them; used statistical or qualitative methods
Features of Groups Experimental Design
Control/Comparison Group, Random Assignment, Pre- and Post-test
Control/Comparison Group
the group that DOES NOT receive the intervention, treatment, stimulus, etc
Random Assignment
randomly assigning participants to different treatment conditions
Pre- and Post-Test
Pre-Test: measure the effects before an intervention
Post-Test: measure the effects after an intervention
Classic experimental Design
(Pretest-Posttest Control Group Design)
R O1 X O2
R O1 O2
Randomization and Pretests
Posttest only control group
R X O1
R O1
No baseline measurement
Impossible to check whether the groups equivalent initially
Internal Validity
our level of confidence in cause-and-effect
Threats to Internal Validity
selection bias, history, testing, maturation, instrumentation, attrition, contamination, placebo effect
Selection Bias
occurs when a treatment group and control group are not comparable at the beginning of the study
History
external events that occur b/t pretest and posttest
Testing
repeatedly taking the same test causes scores to change
Maturation
changes over time naturally during the study, regardless of intervention
Instrument
occurs when there are changes in the measurement tools or procedures used during a study
Attrition
loss of study participants
