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Quasi & Non-Experimental Designs

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Presentation on theme: "Quasi & Non-Experimental Designs"— Presentation transcript:

1 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 _______________.

2 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)

3 Summary of Quasi & Non-experimental designs
Time-series design (One group) Differential/Causal comparative design (Multiple groups) Pretest-posttest non-equivalent control-group design Developmental: Cross Sectional design Developmental: Longitudinal design One-group pretest-posttest design Posttest-only nonequivalent group (Static) design

4 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

5 Pretest-Posttest Non-Equivalent Control-Group Design

6 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

7 Posttest Only (Static) Group Design

8 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

9 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.

10 Intact Group of Participants
Measurement of DV Experimental Condition ____________ Design

11 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 ____________

12 Developmental Research Designs – study age-related changes in behavior
Group at Time 1 (e.g., 10 yrs) (e.g., 20 yrs) (e.g., 40 yrs) 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 _____, ________

13 One-Group Pretest-Posttest Design
1 naturally occurring group Pretest and postest

14 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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