Social Research Glossary


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Citation reference: Harvey, L., 2012-20, Social Research Glossary, Quality Research International,

This is a dynamic glossary and the author would welcome any e-mail suggestions for additions or amendments. Page updated 19 December, 2019 , © Lee Harvey 2012–2020.


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Order effect

core definition

Order effects occur in a succession of social psychological experiments where the earlier treatments may impact on later treatments.

explanatory context

Order effects occur in social psychological experiments where one treatment follows another. Earlier treatments can themselves efffect later ones.


Randomising treatments to a group of subjects is a possible way of overcoming order effects. Alternatively the same subjects could be tested several times under different conditions in order to counterbalance the order effects.


Order effects are usually seen to fall into one of two categories.


First, practice effect where there is an improvement in performance with practice.


Second, fatigue effect, where there is a reduction in performance due to tiredness or boredom

analytical review (undated) prov ides a definition and lists four types:

Order Effects Definition

Order effects refer to differences in research participants' responses that result from the order (e.g., first, second, third) in which the experimental materials are presented to them. Order effects can occur in any kind of research. In survey research, for example, people may answer questions differently depending on the order in which the questions are asked. However, order effects are of special concern in within-subject designs; that is, when the same participants are in all conditions and the researcher wants to compare responses between conditions. The problem is that the order in which the conditions are presented may affect the outcome of the study.

Types of Order Effects

Order effects occur for many reasons. Practice effects occur when participants warm up or improve their performance over time. In reaction time studies, for example, participants usually respond faster as a result of practice with the task.

Participants may also perform differently at the end of an experiment or survey because they are bored or tired. These fatigue effects are more likely when the procedure is lengthy and the task is repetitive or uninteresting. Carryover effects occur when the effect of an experimental condition carries over, influencing performance in a subsequent condition. These effects are more likely when the experimental conditions follow each other quickly. They also depend on the particular sequence of conditions. For example, people's estimates of height may be lower after they have been exposed to professional basketball players than after they have been exposed to professional jockeys. Interference effects occur when previous responses disrupt performance on a subsequent task. They are more likely when the second task quickly follows the first and the response required in the second task conflicts with the response required in the first task.

associated issues


related areas

See also


Researching the Real World Section 9

Sources, nd, 'Order effects', available at, accessed 12 June 2019.

copyright Lee Harvey 2012–2020


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