Types of Experimental Designs Non-experimental –Post-test only –Pre-post test Experimental –Pre & post-test with control group –Pre & multiple post-test with control group –After-only control group –Solomon four-group Quasi –Non-equivalent control group –Simple time-series –Multiple time series

Laboratory vs. Field Experiments Lab –Artificial (Low external validity) –Control of variables (High internal validity) –Good for theory building and process-level understanding Field –Realistic (High external validity) –Less control (Low internal validity) –Good for program evaluation

Non-Experimental No control group No measurement of dependent variable before intervention Referred to as quasi-experiment in Sekaran

Non-Experimental Post-test only –Referred to as quasi-experiment in Sekaran –Measurement taken only after intervention –No baseline measure taken –Hard to determine if change has occurred is due to intervention –Good for studying nature of intervention –Useful for evaluating participant learning after a training session InterventionPost-measure

Non-Experimental Pre-test/post-test –Referred to as quasi-experiment in Sekaran –Change inferred from differences in pre vs. post intervention measures InterventionPost-measurePre-measure

Non-Experimental Pre-test/post-test –Is affected by testing, instrumentation, history, time, maturation, & statistical regression effects –Use internal referencing data to test whether only relevant var changed and irrelevant var did not change following intervention InterventionPost-measurePre-measure

Experimental Control group Random assignment of participants to conditions –Is the study described in the ethnic identity paper (Kim & Gelfand) an experiment? Why or Why not?

Experimental Pre-test/post-test w/control group InterventionPost-measurePre-measure Post-measurePre-measure Experimental group Control group Subject to mortality threats

Experimental Pre-test/post-test w/control group (omnibus test= repeated measures anova) –Experimental group should be ‘better’ than control group on post-test measures (t-test independent groups) –Experimental group scores should “improve” from pre to post-test (t-test paired) –Control group scores should not change from pre to post-test (t-test paired) –Should be no group differences on pre-test measures esp on matching variables if random assignment was not possible (t-test independent groups)

Pre-test & Post-test Control Group with multiple post-test measures Experimental InterventionPost-measure 1,2,3Pre-measure Post-measure 1,2,3Pre-measure Experimental group Control group –Tests long and short term effects of intervention (e.g., training)

Pre-test & Post-test Control Group with multiple post-test measures (adapted to org’n stakeholders’ needs) Experimental InterventionPost-measure 1 Pre- measure Experimental group Control group Control Post- measure 2 Control Post-measure 1 Pre- measure Intervention Post- measure 2

Experimental After only control group InterventionPost-measure Experimental group Control group Eliminates testing effects found in pre-test post-test control group design Classified as quasi-experimental in Sekaran Referred to as post-tests only with experimental & control groups in Sekaran Subject to Selection & mortality threats

Solomon Four-group design Experimental InterventionPost-measurePre-measure Post-measurePre-measure Experimental group Control group InterventionPost-measure Experimental group Control group

TABLE 7.2 Copyright © 2003 John Wiley & Sons, Inc. Sekaran/RESEARCH 4E

Types of Experimental Designs Experimental –Pre & post-test with control group –Pre & multiple post-test with control group –After-only control group –Solomon four-group Quasi –Non-equivalent control group –Simple time-series –Multiple time series

Quasi-Experimental Non-equivalent control group –E.g., training conditions assigned to pre- existing groups –Gather pre-intervention data on important control variables. –Use pre-measure as a statistical control in the analyses for differences in post- intervention measures

Simple time-series design Quasi-Experimental InterventionPost-measure 1,2,3 Pre-measure 1, 2, 3 Pre-measures should not be different from each other Post measures should not be different from each other Pre vs. post measures should be different from each other

Multiple time-series design Quasi-Experimental InterventionPost-measure 1,2,3 Pre-measure 1, 2, 3 Post-measure 1,2,3 Pre-measure 1, 2, 3 Control group Experimental group Same conditions as simple time series design plus.. Pre and post measures of control group should not differ from each other Limitations: Testing effects, instrumentation problems

Types of Experimental Designs Non-experimental –Post-test only –Pre-post test Experimental –Pre & post-test with control group –Pre & multiple post-test with control group –After-only control group –Solomon four-group Quasi –Non-equivalent control group –Simple time-series –Multiple time series