Non-true-experimental Designs, cont.

PSY 231Research Methods in

Psychology

AnnouncementsJournal Article Summary #2 (or research

participation alternative) due in labs this week

bring results from group projects to labGAs will go over plans of analyses with you

todayChapter 12—The Correlational Research Strategy

Chapter 13—The Descriptive Research Strategy

Chapter 10—The Nonexperimental and Quasi-Experimental Strategies: Nonequivalent Group, Pre-Post, and Developmental Designs

Chapter 14—Single-Subject Research Designs

Chapter 15—Statistical Evaluation of Data

balance of the validitiesinternal—extent to which a research study

produces a single, unambiguous explanation for the relationships between two variables

external—extent to which we can generalize the results of a research study to people, settings, times, measures, and characteristics other than those in that study

balance depends on level of experimental control

threats to internal validityassignment biashistorymaturationinstrumentationtesting effects

nonexperimental research vs.

quasi-experimental researchnonexperimental—intended to demonstrate

a relationship between variables but does not attempt to explain

quasi-experimental—uses some rigor and control of true experiments but contains a flaw that prevents cause-effect

remember—true experiments includea control groupmanipulation of independent variable(s)random assignment to groups

nonexperimental research vs.

quasi-experimental researchboth use comparisons between groups or

conditionsboth use nonmanipulated independent

variables attempts to control internal validity threats

nonexperimental—noquasi-experimental—yes

nonexperimental research vs.

quasi-experimental researchtwo types

between-subjects designsnonequivalent groups

within-subjects designspre-post designs

nonequivalent groups designs

posttest-only nonequivalent groupsassignment bias, no control of time effectsnonexperimental

participants program measure

participants no program measure

example smokerparticipants training program measure

smokers no training program measure

nonequivalent groups designs

pretest-posttest nonequivalent control designassignment bias, some control of time effectsquasi-experimentalparticipants measure program

measure

participants measure no programmeasure

example no t.v. aggression

aggressionparticipants measure t.v.

measure

t.v. aggression aggression

participants measure (no change)measure

pre-post designsone-group pretest-posttest design

little control of time effectsnonexperimental

participants measure programmeasure

example smokerparticipants measure program

measure

pre-post designstime-series design

some control of time effectsquasi-experimental

measure measure measure measure

program

measure measure measure measure

example1951 1952 1953 1954

1955

1959 1958 1957 1956

developmental designsnonmanipulated independent variable—age

or timethree types

cross-sectionallongitudinalsequential

cross-sectional designdifferent participants, at different ages,

studied at same time

year of birth

1988 1978 1968 1958 1948

age at study

20 30 40 50 60

year of study

2008

cross-sectional designadvantages

time efficientno long-term

cooperationdisadvantages

no individual changes

cohort effects

year of birth

1988 1978 1968 1958 1948

age at study

20 30 40 50 60

year of study 2008

longitudinal designsame participants, at different ages,

studied at different times

year of birth

1988

age at study

20 30 40 50 60

year of study

2008 2018 2028 2038 2048

longitudinal designadvantages

no cohort effectsassesses individual

changesdisadvantages

time consuminglong-term

cooperation

year of birth 1988

age at study

20 30 40 50 60

year of study

2008 2018 2028 2038 2048

sequential designdifferent participants, at different ages,

studied at different times

20 30 40 50 60

20 30 40 50

age at study

20 30 40

20 30

20

year of study 2008 2018 2028 2038 2048

single-subject designsoriginally used in behavior modification often seen in clinical and applied settingsnot used very often in traditional research

single-subject designsdifferent from traditional designs

usually conducted with one person or a small group

much more flexiblerequire continuous assessment

single-subject designsbaseline observations—no treatment

administeredbaseline phase—series of baseline

observationstreatment observations—treatment

administeredtreatment phase—series of treatment

observations

reversal designalso called ABAB designbehavior is observed during

baseline phase (A)treatment phase (B)baseline phase (A)treatment phase (B)

reversal design

A B A B

multiple baseline designsreversal designs may not workneed to show treatment is effective across

circumstancesmultiple baseline across

subjectsbehaviorssituations

single-subject designsadvantages

establish cause-effect between treatment and behavior

integrate experimental research with clinical practice

allows flexibility

single-subject designsdisadvantages

cause-effect established for only one personneeds multiple observationsno statistical control

feedbackthinking about my 2 lectures…

please write down 1 thing you likedplease write down 1 thing that you didn’t

like/need to improveturn it in on the table along with Rating

Sheet #1