Contents of It's not All in Your Head by Asmundson and Taylor

2. METHOD
2.1. Participants
Previous randomized controlled trials for health anxiety were consulted in order to
determine an adequate sample size for this feasibility trial. Based on the samples of those
studies (e.g., Martínez & Botella, 2005, 12 participants; Bouman, 2002, 21 participants;
Bleichhardt, Timmer, & Rief 2005, 27 participants; and Wattar et al., 2005, 16
participants), a sample of 20 participants was chosen. A sample of 20 could produce a
large effect size (d = 2.00; power = 1.00, high power) based on the study‘s primary
outcome measure, the Short Health Anxiety Inventory (SHAI; Salkovskis, Rimes,
Warwick, & Clark, 2002). Ethical clearance was sought and received from the University
of Regina Research Ethics Board (see Appendix E). Twenty participants meeting the
inclusion criteria described below were recruited from the city of Regina, Saskatchewan,
Canada.
The study was advertised on the Internet using fee-based and free online classified
websites, free classified newspapers, and posters distributed across the University of
Regina campus, local physicians‘ offices, gyms, and community bulletin boards (see
poster in Appendix E). Initially, a research assistant or the Head Researcher prescreened
participants by telephone from the Anxiety and Illness Behaviours Laboratory (AIBL) at
the University of Regina and informed consent was obtained prior to asking any
questions. After using this method with some participants the screening was changed to
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