Campus Units

Human Development and Family Studies

Document Type

Article

Publication Version

Published Version

Publication Date

2-2013

Journal or Book Title

Journal of MultiDisciplinary Evaluation

Volume

9

Issue

20

First Page

33

Last Page

42

Abstract

Background: This paper addresses one threat to the internal validity of a randomized controlled trial (RCT), selection bias. Many authors argue that random allocation is used to ensure baseline equality between study conditions in a given study and that statistically significant differences at pretest mean that randomisation has failed.

Purpose: The purpose of this study was to clarify the role of random allocation in an RCT study. Is the role of random allocation to protect against selection bias? And does it have a further role, namely to ensure baseline equality and the absence of statistically significant differences between study conditions at pretest?

Setting: The participants for this study were 229 children in 1st and 2nd grade and data were collected as part of an RCT evaluation of a volunteer reading programme piloted in Ireland, Wizards of Words (WoW).

Comments

This is an article from Journal of MultiDisciplinary Evaluation, 2013, 9(20); 33-42. Posted with permission.

Copyright Owner

Journal of MultiDisciplinary Evaluation, Western Michigan University.

Language

en

File Format

application/pdf

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