Quasi & Non-Experimental Designs
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Quasi & Non-Experimental Designs. Quasi-Experimental designs: Not quite true experiments because the different groups/conditions are not created by __________________. Groups or conditions are defined by _____________ variable or a ______ variable.

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Quasi & Non-Experimental Designs

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Quasi non experimental designs

Quasi & Non-Experimental Designs

Quasi-Experimental designs: Not quite true experiments because the different groups/conditions are not created by __________________. Groups or conditions are defined by _____________ variable or a ______ variable.

Non-Experimental designs – do not allow you to rule out many threats to _______________.


Quasi non experimental designs

Quasi & Non-Experimental Designs

  • Those using ____ group, compare behavior across _____:

  • Time-series designs (quasi-experimental)

  • One group pretest-posttest (non-experimental)

  • Longitudinal design (non-experimental

  • Those using multiple, ____________ groups:

  • Pretest-posttest nonequivalent control group design (quasi-experimental)

  • Posttest-only control group design (Static-group design) (non-experimental)

  • Differential (Causal-comparative) design (non-experimental)

  • Cross-sectional design (non-experimental)


Quasi non experimental designs

Summary of Quasi & Non-experimental designs


When would you use a quasi experimental design

When would you use a quasi-experimental design?

  • When you want to investigate a relationship but cannot create ________ assign groups

  • It is not _________ to create randomly assigned groups


Quasi non experimental designs

Pretest-Posttest Non-Equivalent Control-Group Design


Pretest posttest nonequivalent control group design

Pretest-Posttest Nonequivalent Control-Group Design

  • Definition: A quasi-experimental design in which behavior in two _______________groups is measured pre and post-IV

  • No random __________ and ___________

  • Because you measure behavior before treatment you can evaluate group equivalence - it reduces the threat of _______________

    • e.g., Effects of Flexible vs. fixed work hours on productivity in two factories

    • e.g., Effects of Home-based vs. School-based treatment on problem behavior


Quasi non experimental designs

Posttest Only (Static) Group Design


Posttest only static group design

Posttest Only (Static) Group Design

  • No random selection and assignment

  • 2 __________________, e.g., children in 2 clinics

  • Groups should be ______

  • Susceptible to internal validity threats, e.g., assignment bias (selection threat) - group assignment is _______

    • Example: effects of peer tutoring in two classrooms


Time series design

Time-Series Design

  • Definition: A quasi experimental design in which behavior in one group of participants is measured across time _______________ an IV is implemented.

  • ___________________ control for multiple threats to internal validity

  • Allows you to evaluate _________ across time

  • Called ___________________ when the IV is not created by the experimenter

  • Called a time series design with _______________if the treatment is repeatedly presented across multiple groups.


Quasi non experimental designs

Intact Group of Participants

Measurement

of DV

Measurement

of DV

Measurement

of DV

Measurement

of DV

Measurement

of DV

Experimental

Condition

____________ Design


Time series design1

Time-Series Design

Example: Effects of anti-smoking campaign on smoking frequency

No ______ group – hard to tell if campaign was effective

Time Series – Effect was just part of periodic ____________

Time Series – Effect was just part of downward ________

Time Series – Effect occurs only after ____________


Quasi non experimental designs

Group at

Time 1

(e.g., 10 yrs)

Group at

Time 1

(e.g., 20 yrs)

Group at

Time 1

(e.g., 40 yrs)

Developmental Research Designs – study age-related changes in behavior

Longitudinal design

  • Measuring a variable in individuals over an ___________________

  • Like a time-series design with no _______________

  • Can determine how an individual _________

  • No cohort effects

  • Very _____________, expensive

  • Problems with _____, ________


Quasi non experimental designs

One-Group Pretest-Posttest Design

1 naturally occurring group

Pretest and postest


Quasi non experimental designs

One Group Pretest-Posttest Design

  • Observation made in ____ group before and after treatment

  • No attempt is made to control for many threats to ________________


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