Generating constrained randomized sequences: Item frequency matters
Category
Journal Article
Authors
French, R. M., Perruchet, P.
Year
2009
Title
Generating constrained randomized sequences: Item frequency matters
Journal / book / conference
Behavior Research Methods
Abstract
All experimental psychologists understand the importance of randomizing lists of items. However, randomization is generally constrained and these constraints, in particular, not allowing immediately repeated items, which are designed to eliminate particular biases, frequently engender others. We describe a simple Monte Carlo randomization technique that solves a number of these problems. However, in many experimental settings, we are concerned not only with the number and distribution of items, but also with the number and distribution of transitions between items. The above algorithm provides no control over this. We, therefore, introduce a simple technique using transition tables for generating correctly randomized sequences. We present an analytic method of producing item-pair frequency tables and item-pair transitional probability tables when immediate repetitions are not allowed. We illustrate these difficulties – and how to overcome them – with reference to a classic paper on infant word segmentation. Finally, we make available an Excel file that allows users to generate transition tables with up to ten different item types, and to generate appropriately distributed randomized sequences of any length without immediately repeated elements. This file is freely available at : http://leadserv.u-bourgogne.fr/IMG/xls/TransitionMatrix.xls
Issue
4
Volume
41
Pages
1233-1241