Overcoming Perfectionism: A Randomised Controlled Trial of an Online CBT Based Guided Self-help Intervention

This self-report measure consists of 36 items grouped into six subscales. Participants respond on a five point scale ranging from 1 = "strongly disagree" to 5 = "strongly agree". The measure has been found to be both reliable and valid for use with non-clinical and clinical populations (Frost et al., 1990; Hewitt & Flett, 1991; Hewitt, Flett, Turnbull-Donovan, & Mikail, 1991). Participants will be considered eligible for inclusion in the study if they score one standard deviation above published norms on the Concern over Mistakes subscale, i.e. a score of ≥ 29. This measure has been amended to reflect participants experience over the past month allowing us to measure change.

The OCI-R, a shortened version of the Obsessive-Compulsive Inventory, assesses symptoms of OCD. The measure consists of 18 items (e.g. "I frequently have get nasty thoughts and have difficulty in getting rid of them"). On a five point scale, respondents rate how distressed or bothered they have been in the past month by the symptom described, with responses ranging from "Not at all" to "Extremely." It has been found to have good validity and reliability in both clinical and non-clinical samples (Abramowitz & Deacon, 2006; Foa et al., 2002; Hajcak, Huppert, Simons, & Foa, 2004; Huppert et al., 2007).

The EDE-Q assesses for symptoms of the eating disorders: Anorexia Nervosa (AN), Bulimia Nervosa (BN), Binge Eating Disorder (BED) and sub-threshold variants. The measure consists of 28 items rated on a seven point scale appropriate to the item: number of days a symptom has been experienced over the past month, ranging from no days to every day; and for remaining questions (e.g. "How dissatisfied have you been with your weight?") responses ranging from "Not at all" to "Markedly." It has been found to have good reliability, and has been validated for use among clinical and community samples (Aardoom, Dingemans, Op't Landt, & Van Furth, 2012; Carter, Stewart, & Fairburn, 2001; J. M. Mond, Hay, Rodgers, Owen, & Beumont, 2004; Jonathan M Mond et al., 2008; Reas, Grilo, & Masheb, 2006).

The DASS is a 42 item self-report measure of depression, anxiety and stress (e.g. "I found myself getting upset by quite trivial things"), rated on a four point scale ranging from "Did not apply to me at all" to "Applied to me very much or most of the time." It has been shown to be reliable and has been validated for use among clinical and community samples (Brown, Chorpita, Korotitsch, & Barlow, 1997; Crawford & Henry, 2003; Page, Hooke, & Morrison, 2007).

The VOCI-MC is a self-report measure that assesses symptoms of mental contamination. The measure consists of 20 items (e.g. "Often I look clean but feel dirty), rated on a five point scale ranging from "Not at all" to "Very much." It has been shown to be reliable and valid for use among clinical and community samples (Coughtrey, Shafran, Knibbs, & Rachman, 2012; Coughtrey, Shafran, & Rachman, 2013; Radomsky et al., 2014).

This self-report measure consists of 12 items (e.g. "Have you pushed yourself really hard to meet your goals?" and "Have you raised your standards because you thought they were too easy?"). Participants respond on a four point scale ranging from 1 = "not at all" to 4 = "all the time". This measure of clinical perfectionism was created by Fairburn, Cooper and Shafran at the University of Oxford, and has been found to have good reliability and validity in two community samples and an ED sample; participants will be considered eligible for inclusion if they score similarly to this psychiatric population (i.e. a score of ≥ 29) (Egan, Shafran, et al., 2014). This measure has been amended to reflect participants experience over the past week, allowing us to monitor change on a weekly basis.

This measure consists of three scales which assess fear of compassion for self (e.g. "I worry that if I start to develop compassion for myself I will become dependent on it"), fear of compassion from others (e.g. "I try to keep my distance from others, even if I know they are kind"), and fear of compassion for others (e.g. "Being too compassionate makes people soft and easy to take advantage of"). The FCS is made up of 38 items in total which are rated on a four point scale ranging from 0 = "Don't agree at all" to 4 = "Completely agree." It has been shown to be reliable, and valid for use among clinical and community samples (P Gilbert et al., 2012; Paul Gilbert et al., 2011).

This measure of self-esteem consists of 10 items (e.g. "On the whole I am satisfied with myself" and "I wish I could have more respect for myself") and is rated on a four point scale ranging from 1 = "strongly disagree" to 4 = "strongly agree" It has been found to be reliable, and been validated for use among clinical and community samples (Bagley & Mallick, 2001; Ferring & Filipp, 1996; Martín-Albo, Núñez, Navarro, & Grijalvo, 2007; Phillips, Pinto, & Jain, 2004; Schmitt & Allik, 2005; Shaw-Zirt, Popali-Lehane, Chaplin, & Bergman, 2005).

The IoU consists of 27 items (e.g. "Uncertainty stops me from having a firm opinion" and "It's unfair not having any guarantees in life"), and is rated on a five point scale ranging from 1 = "Not at all characteristic of me" to 5 = "Entirely characteristic of me." It has been found to be reliable, and has been validated for use among clinical and community samples (Kristine Buhr & Dugas, 2002; Kristin Buhr & Dugas, 2006; Jacoby, Fabricant, Leonard, Riemann, & Abramowitz, 2013).

The WEMWBS is a 14 item self-report measure of mental well-being that focuses on positive aspects of mental health, including subjective well-being, psychological functioning (including autonomy, competence, self-acceptance, and personal growth), and interpersonal relationships. Examples of items include, "I have been feeling optimistic about the future," "I have been feeling confident," and "I have been dealing with problems well." Participants respond on a five point scale, ranging from 1 = "none of the time" to 5 = "all of the time." The WEMWBS has shown good reliability (0.83) and has been validated for use among student and population samples (Clarke et al., 2011; Maheswaran, Weich, Powell, & Stewart-Brown, 2012; Tennant et al., 2007).