SOCI2000 6.3 The Experiment: Types of Experiments

Lecture Slides

Week 6 Lecture Slides

Video Lecture (from 2019)


Classical Experimental design

Independent variable

Dependent variable

Random assignment



Experimental group

Control group

Key Concepts:

Double-blind experiment





Types of experiments:

Classical experimental design

True experiment


One-shot case study

Natural experiment

Field experiment


Internal validity

External validity




Classical experimental design

An experiment with seven elements:

  • Independent variable
  • Dependent variable
  • Pretest
  • Posttest
  • Control group
  • Experimental group
  • Random assignment

True experiment

An experiment with true random assignment of cases to the control and experimental groups.

E.g. Measure ‘happiness’ after coin flip assigns to drink ‘coke’ or ‘pepsi’.

Quasi-experiment (observational study)

An experiment lacking true random assignment.

E.g. Measure ‘happiness’ of people who regularly drink either ‘coke’ or ‘pepsi’.

One shot case study

An experiment where there is only one experimental group who are observed only once, after experiencing an event.

E.g. Measure ‘emotional distress’ of families of plane crash victims.

Natural experiment

A situation which was not designed as an experiment, but which can be studied using the logic of experiments.

E.g. Compare life expectancy of countries with and without universal public health care systems.

Field experiment (vs lab experiment)

An experiment conducted in some sort of more realistic or natural environment (as compared to in a laboratory).

E.g. Measuring likelihood of lending a phone to people of different ethnicities in a shopping centre (as compared to doing it a similar test on a computer screen in a laboratory, or in a survey).

Last updated on 13 April, 2020 by Dr Nicholas Harrigan (