5.3 Experimental and Quasi-Experimental Designs

Question 1

Types of Quantitative Research Designs

Answer 1

• Experimental
• Quasi-experimental
• Non-experimental

Question 2

Experimental

Answer 2

Gold Standard - Randomized control trial (RCT) - Level 2 evidence.
Systematic review of RCT’s are level 1 evidence

CONCEPTS THAT MUST BE PRESENT IN EXPERIMENTAL DESIGN
- Randomization
- Control
- Manipulation (All experimental designs involve the manipulation of the independent variable (cause) and measurement of a dependent variable (effect).
- NOTE casual relationships are difficult to establish so researchers should avoid the word “prove” when discussing hypothesis testing

Question 3

Types of Experimental Designs

Answer 3

• Classic Randomized Clinical Trials
• Solomon four-group design
• After-Only Experimental Design

Question 4

Classic Randomized Clinical Trial

Answer 4

STEPS
- Sample is selected from the population
- Baseline is collected
- Subjects are randomized
- 2 Groups (intervention and control group)
- Post intervention data is collected from each group

Question 5

Solomon Four-Group Design

Answer 5

STEPS
- Sample is selected from the population
- Subjects are randomized into 4 groups that vary based on collected baseline data
- Control and intervention groups are created for both when baseline data is collected and baseline data is not collected
- After this postintervention data is collected

Question 6

After-Only Experimental Design

Answer 6

STEPS
- Subjects are randomized into an intervention and control group
- Post intervention data is collected

Question 7

Strengths/Weaknesses of an Experimental Design

Answer 7

Strengths
- Gold standard and best at testing cause-effect relationships.
- Control, manipulation, and randomization is one of the best ways to measure differences between 2 groups

Cons
- Complicated and costly
- Many variables related to patient care outcomes cannot be manipulated due to ethical concerns

Question 8

Quasi-Experimental Design

Answer 8

• Difference between experimental and quasi-experimental is that quasi does not contain either a control group or random assignment
• Weaker cause-effect relationship
• Level 3 evidence

Question 9

Types of Quasi-Experimental Designs

Answer 9

• Nonequivalent Control Group
• After-Only Nonequivalent control design
• One-group (Pretest/Posttest)
• Time series design

Question 10

Nonequivalent Control Group Design

Answer 10

STEPS
- 2 groups are created, control and intervention group
- Baseline data is collected
- Intervention is applied to the experimental group
- Postintervention data is collected for the experimental group and data is collected again for the control group.

Question 11

After-Only Non-equivalent Control Group Design

Answer 11

STEPS
- 2 Groups created (control and intervention)
- Intervention is applied to experimental group
- Postintervention data collected for experimental group, data collected from control group

Question 12

One-Group (Pretest, Posttest) Design

Answer 12

STEPS
- Only experimental group is created
- Baseline data is collected
- Intervention is applied
- Postintervention data is collected

Question 13

Time-Series Design

Answer 13

STEPS
- Experimental design is collected
- Data is collected twice prior to intervention
- Intervention is applied
- Post-Intervention data is collected twice

Question 14

Strengths/Weaknesses of Quasi-experimental Design

Answer 14

Strengths
- Practical, feasible, cost-effective, potential generalizable findings, more adaptable to real-world settings

Weakness
- Inability to make clear cause-effect determinations. Did manipulation of independent variable actually affect the change in the dependent variable