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Journal Article Link 4.1: Colagiuri, B. (2010). Participant expectancies in double-blind randomized placebo-controlled trials: Potential limitations to trial validity. Clinical Trials, 7(3), 246-255.

Background Randomized controlled trials (RCTs) that use placebo controls to achieve double-blinding intend to establish the efficacy of a treatment over and above expectancy and other forms of bias. Despite this, a growing body of research suggests that participant expectancies can influence the outcomes of these trials. Purpose and Methods This nonsystematic review examines research assessing the role of participant expectancies in double-blind placebo-controlled RCTs in order to determine if and how they can limit these types of trials. Results There appear to be at least three ways in which participant expectancies can limit the validity of double-blind placebo-controlled RCTs. First, when blinding fails researches cannot determine whether any observed improvement in the group receiving active treatment resulted because of the treatment’s effect or because of participants’ expectancies. Second, participant expectancies could create ceiling effects if there are strong placebo effects in each treatment arm and this may falsely suggest that the active treatment is ineffective without expectancy. Third, the knowledge that a participant will be allocated active treatment or placebo in double-blind placebo-controlled RCTs is likely to lead to weaker treatment responses than would be expected in standard clinical practice, in which patients are unlikely to doubt that they have been given an active treatment. Conclusions Participants’ expectancies can undermine the validity of double-blind placebo-controlled RCTs. Researchers conducting these trials should assess participants’ beliefs about their treatment allocation and actively investigate if and how these beliefs may have influenced the trial’s outcome.

1. Describe a double-blind randomized placebo-controlled trial
2. Give an example of participant expectancies and how it can affect the outcome of a study
3. In addition to suggestions provided by the article, how could researchers decrease participant expectancies in a study?

Journal Article Link 4.2: Lee, H., & Turney, K. (2012). Investigating the Relationship between Perceived Discrimination, Social Status, and Mental Health. Society and Mental Health, 2(1), 1-20.

A growing body of evidence suggests that experiences with discrimination have implications for mental health and that these associations may vary by social status. We use data from the Chicago Community Adult Health Study (CCAHS) to examine how two types of perceived discrimination, chronic everyday discrimination and major lifetime discrimination, are linked to mental health and how this association varies by race/ethnicity, gender, and socioeconomic status. Results indicate that everyday discrimination is generally independently linked to greater depressive symptoms, loneliness, and hostility across all social status groups. Major discrimination is not associated with depressive symptoms or loneliness after adjusting for a host of covariates but is associated with hostility, especially for certain groups. These findings highlight the need to examine multiple indicators of discrimination and mental health and to pay attention to both differences and similarities in these associations by social status.

1. Identify all variables in the study
2. How was each variable operationally defined?
3. How was each variable measured?
4. What was the scale of measurement for each variable?