Chapter 3

Key Terms

Hypotheses: predictions concerning the effects of some factor(s) on behaviour based on a given theory.

Experimental method: a method involving control over the experimental situation (especially the independent variable).

Experimental hypothesis:  prediction as to what will happen in a given experiment; it typically involves predicting the effect of an independent variable on a dependent variable and is often theory-based.

Independent variable: some aspect of the experimental situation manipulated by the experimenter to test a given experimental hypothesis.

Dependent variable: some aspect of the participants’ behaviour that is measured to test a given experimental hypothesis.

Null hypothesis: prediction that the independent variable (manipulated by the experimenter) will have no effect on the dependent variable (some measure of behaviour).

Confounding variables: variables not of interest to the experimenter erroneously manipulated along with the independent variable.

Sample: the participants actually used in a study drawn from some larger population.

Population: a large collection of individuals (e.g., female musicians) from whom the sample used in a study is drawn.

Representative sample: a sample of participants selected to be typical or representative of the population from which it is drawn.

Random sampling: selecting the individuals for a sample from a population using some random process.

Quota sampling: selecting a sample from a population so that those selected are similar to it in certain respects (e.g., proportion of females).

Opportunity sampling: selecting a sample of participants simply because they happen to be available.

Independent design: an experimental design in which each group consists of different participants.

Matched participants design: an experimental design in which participants in two groups are matched in terms of some relevant factor(s).

Repeated measures design: an experimental design in which each participant appears in both groups.

Randomisation: assigning participants to groups at random (e.g., by tossing a coin).

Counterbalancing: this is used with the repeated measures design: each condition is equally likely to be used first or second.

Experimenter effect: unintended influences of the experimenter’s behaviour on that of the participants in an experiment.

Ecological validity: the applicability or relevance of experimental findings to everyday settings.

Demand characteristics: cues used by participants to work out what the experiment is about.

Implacable experimenter: the typical laboratory situation in which the experimenter’s behaviour is uninfluenced by the participant’s behaviour.

Replication: repeating the findings of a previous study using the same design and procedures.

Inter-observer reliability:  the extent of agreement between two observers rating the behaviour of participants.

Cross-sectional method: different groups (e.g., varying in age) are all studied at the same time.

Longitudinal method: one group of participants is tested repeatedly over a relatively long period of time.

Correlation: an association (positive or negative) between two dependent variables or responses produced by the participants.

Case study: the intensive study of one or two individuals.

Weblinks

A video introduction to scientific research methods in psychology
http://www.youtube.com/watch?v=PrlI9oErJJg

American Psychological Association: Lots of information on research in psychology
http://www.apa.org/research/index.aspx

Clear and concise explanations of various aspects of research methods and the scientific process
http://www.experiment-resources.com/

A short summary on how to write hypotheses
https://www.youtube.com/watch?v=xtgyIm1IfHY

Basic experimental method: A simple and straightforward guide. Includes links to more about psychology research, related topics and articles, and suggested reading
http://psychology.about.com/od/researchmethods/a/simpexperiment.htm

Case study research design
http://explorable.com/case-study-research-design.html

The British Psychological Society’s full Code of Ethics and Conduct
https://beta.bps.org.uk/sites/beta.bps.org.uk/files/Policy%20-%20Files/Code%20of%20Ethics%20and%20Conduct%20%282009%29.pdf

What’s the most important psychology experiment that’s never been done?
http://bps-research-digest.blogspot.co.uk/2007/09/most-important-psychology-experiment.html

The Experimental Psychology Society
http://www.eps.ac.uk/