PSY2 – Research Methods: Lesson 06

Experimental design

PSY2 RM PowerpointTeachers or students who want the original PPT please tweet @psychopepper

Learning Objectives

  • To KNOW and UNDERSTAND what the term experimental design means.
  • To KNOW and UNDERSTAND what the  features are of a the independent group design, matched pairs design and repeated measure design.
  • To EVALUATE the strengths and limitations of independent group design, matched pairs design and repeated measure design.

Lesson Outline:

Tasks:

  1. To complete and peer assess question D2 in booklet to check knowledge from previous lessons.
  2. To take notes in booklet on what experimental design is.
  3. To work in groups to discover what one of the experimental designs is, and it’s strengths and limitations in order to devise a short role play of an experiment happening which uses it.
  4. To take notes in booklet on the descriptions, strengths and limitations of all three types of experimental design.

Content Recap:

Experimental Design: The way in which participants and variables are distributed (levels of IV) in order to make comparisons about DV performance.

Independent Groups: An experimental design where you recruit a pool of participants and then split them into two different groups who each only experience one of the conditions of the test.

Random Allocation: An important concept in independent group design where each participants is randomly allocated to which condition they will receive to reduce bias.

Repeated Measures: An experimental design where you recruit a pool of participants and then get all participants to experience all conditions of the test.

Order Effects: Due to participants repeating the procedure with only one small change they can be effected by boredom, fatigue or practise.  This means they are better (or sometimes worse) on the second test but not because of the IV.

Counterbalancing: A way to overcome order effects is to have half of your participants complete condition A then condition B, whilst the other half complete condition B then condition A.  This means it should counter any effect of doing the test twice, as half will be effected in condition A and the other half in condition B.  Sometimes seen as ABBA.

Matched Pairs: An experimental design where you recruit a pool of participants and match them on criteria relevant to your study (e.g. IQ) then one of each  pair completes one of the experimental conditions.

If you would like to access PsychoPepper’s Glossary of Terms please click here

Resources used

Experimental Design Allocation Cards

Study Notes (TBC):

If you would like to download a set of study notes for this lesson, you can do so here.  If you would like access to the original word file please tweet @psychopepper

TEXTBOOKS OR EXTRA READING:

I would suggest that you have a copy of one of the textbooks which will allow you to read around the subject matter, pre-read ahead of lessons or even take extra notes/practise questions afterwards.  I would recommend the following (you do not need to replicate books, one of each type is plenty!)

Extra ReadingElephants on Acid or Hippo Eats Dwarf

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