'Dark Triad, Sleep and Metabolic Syndrome in Affective Disorders' (AsPredicted #78276)
Created: 10/28/2021 03:16 AM (PT)
This is an anonymized version of the pre-registration. It was created by the author(s) to use during peer-review.
A non-anonymized version (containing author names) should be made available by the authors when the work it supports is made public.
1) Have any data been collected for this study already? No, no data have been collected for this study yet.
2) What's the main question being asked or hypothesis being tested in this study? Q1) Is there an association between the metabolic syndrome and the individual maifestation in the Dark Triad traits in patients with affective disorders?
Q2) Is there a difference between women and men with affective disorders between the individual manifestation in the Dark Triad traits and the presence of metabolic syndrome?
Q3) Is sleep quality dependent on the metabolic syndrome and the individual expression of the Dark Triad traits in individuals with affective disorders?
The following hypotheses will be examined:
H1) Individuals with affective disorders and higher Dark Triad scores are more likely to meet the criteria for a metabolic syndrome than individuals with lower scores in the Dark Triad traits.
H2) In female patients with affective disorders, the relationship between the individual manifestation of the Dark Triad traits and the presence of metabolic syndrome is greater than in male patients with affective disorders.
H3) Sleep quality is worse in individuals with affective disorders if they meet criteria for a metabolic syndrome and report a higher score in the Dark Triad traits.
3) Describe the key dependent variable(s) specifying how they will be measured. This study is essentially correlative. All key variables are enlisted below.
Sleep Quality. Sleep quality will be measured with the German version of Pittsburgh Sleep Quality Index (PSQI; Buysse et al., 1989), which consists of 19 items. Subjects answer on a four-point Likert scale, ranging from (1) „not during the past month" to (4) „three or more times a week".
Dark Triad. The Dark Triad will be measured with the German version of the Short Dark Triad questionnaire (SD3; Jones & Paulhus, 2014), which consists of 27 items. Subjects answer on a five-point Likert scale, ranging from (1) = "strongly disagree" to (5) = "strongly agree".
For the questionnaires, responses will be averaged over items to build (sub-) scale scores. Specifically, a composite score will be calculated for the Dark Triad traits.
Metabolic syndrome. In order to determine the metabolic syndrome, various physical parameters will be collected (blood pressure, plasma glucose level (fasting), HDL- value, triglycerides, waist and hip circumference, medication records).
4) How many and which conditions will participants be assigned to? There will be no conditions.
5) Specify exactly which analyses you will conduct to examine the main question/hypothesis. Before we examine the hypotheses, we will compute bivariate correlations between all items in this study. All correlation analyses will be calculated with Bonferroni adjustments for the family of predictors (α = .05 divided by 3 (Dark Triad traits) and 1 (sleep quality)). To investigate the relationship between metabolic syndrome and Dark Triad traits (H1), we will compute point-biserial correlations. In order to examine the relationship between gender, metabolic syndrome and Dark Triad scores (H2), as well as the relationship between sleep quality, metabolic syndrome and Dark Triad scores (H3), we will calculate two-way analyses of variance with consecutive Bonferroni-adjusted post-hoc t-tests to determine group differences.
6) Describe exactly how outliers will be defined and handled, and your precise rule(s) for excluding observations. Only people within the age of 18-90 will be tested. Outliers will be considered in further analyses. Data will only be excluded if they are not plausible or realistic (e.g. participants skipped parts of the questionnaires). Plausible data (e.g. high narcissism scores) will not be excluded.
7) How many observations will be collected or what will determine sample size? No need to justify decision, but be precise about exactly how the number will be determined. Due to a lack of previous literature, a small effect size was assumed for correlation analyses (r =.3). With an α-level of 5% and a power of 80%, the minimum sample size is N = 82. However, if more data are available, they will also be included in all analyses.
8) Anything else you would like to pre-register? (e.g., secondary analyses, variables collected for exploratory purposes, unusual analyses planned?)
