# Lecture Slides

# Video Lecture (from 2019)

# Concepts

Classical Experimental design

Independent variable

Dependent variable

Random assignment

Pretest

Posttest

Experimental group

Control group

Key Concepts:

Double-blind experiment

Confederates

Placebo

Deception

Debrief

Types of experiments:

Classical experimental design

True experiment

Quasi-experiment

One-shot case study

Natural experiment

Field experiment

Validity:

Internal validity

External validity

Variable:

Conceptual

Operational

# Random Assignment

**Random assignment** = Using a mathematically random process to sort participants into two or more groups.

E.g. Flip a coin to assign to groups

**Matching cases** = An alternative to random assignment, where for every participant in experimental group, another participant is found for control group with almost identical characteristics

E.g. Create two groups of countries: one with minimum wage, one without. Use matching to make sure each case is matched with a case with similar GDP per capita.

# The classical experimental design

The classical experimental design includes:

**Independent variable**= treatment (cause)**Dependent variable**= outcome (effect)**Pretest**= A measurement of the dependent variable before introducing the independent variable**Posttest**= A measurement of the dependent variable after introducing the independent variable**Experimental group**= a group that receives the independent variable (or receives a higher level of it)**Control group**= a group that does not receive the independent variable (or receives a lower level of it)**Random assignment**= mathematically random assignment to control or experimental group.