Within-person Standard Deviation Research Articles

Assessing Validity and Bias of Within-Person Variability in Affect and Personality.

Within-person variability in affect (e.g., Neuroticism) and personality have been linked to well-being. These are measured either by asking people to report how variable they are or to give multiple reports on the construct and calculating a within-person standard deviation adjusted for confounding by the person-level mean. The two measures are weakly correlated with one another and the links of variability with well-being depend on which measure researchers use. Recent research suggests that people's repeated ratings may be biased by response styles. In a 7-day study (N = 399) with up to five measurements per day, we confirmed that the measures of variability lacked sufficient convergent validity to be used interchangeably. We found only 1 significant correlation (of 10) between variability in repeated ratings of affect or personality and variability in repeated ratings of a theoretically unrelated construct (i.e., features of images). There was very little evidence supporting the response styles hypothesis.

Adherence to behavioral recommendations of cognitive behavioral therapy for insomnia predicts medication use after a structured medication taper.

Cognitive behavioral therapy for insomnia (CBTI) has been paired with supervised medication tapering to help hypnotic-dependent individuals discontinue their hypnotics. This study examined the hypothesis that higher participant adherence to behavioral recommendations of CBTI will predict lower odds of using sleep medications 3 months after completion of a combined CBTI/sleep medication tapering protocol. Fifty-eight individuals who used sedative hypnotics completed four CBTI sessions followed by sleep medication tapering. Logistic regression was used to examine the association of stability of time in bed and stability of rise time (measured as the within-person standard deviation) at completion of CBTI with two outcomes at 3-month follow-up: use of sedative hypnotics and use of any medication/substance for sleep. Participants with more stability in their rise time after CBTI than at baseline (ie, a decrease in their within-person standard deviation) had 69.5% lower odds of using sedative hypnotics at follow-up (odds ratio = 0.305, 95% confidence interval = 0.095-0.979, P = .046) than individuals who had no change or a decrease in the stability of their rise time. Results were similar for time in bed: participants with more stability in their time in bed after CBTI than at baseline had 83.2% lower odds of using sedative hypnotics (odds ratio = 0.168, 95% confidence interval = 0.049-0.580, P = .005). Increase in stability of rise time and stability of time in bed was also associated with reduced odds of using any medication/substance for sleep at follow-up. Participants who implement behavioral recommendations of CBTI appear to have more success with discontinuing use of sleep medications. Registry: ClinicalTrials.gov; Name: The Role of Tapering Pace and Selected Traits on Hypnotic Discontinuation; URL: https://clinicaltrials.gov/ct2/show/NCT02831894; Identifier: NCT02831894. Edinger JD, Wamboldt FS, Johnson RL, etal. Adherence to behavioral recommendations of cognitive behavioral therapy for insomnia predicts medication use after a structured medication taper. J Clin Sleep Med. 2023;19(8):1495-1503.

Reproducibility of plasma glucose responses to moderate-intensity exercise in individuals with type 1 diabetes.

To examine the within-person variability in plasma glucose responses to moderate-intensity morning exercise in young individuals with type 1 diabetes after overnight fasting and under basal insulin conditions. In this pilot study, eight participants completed 40 min of moderate-intensity exercise at 60% V̇O2 peak on three separate days. The within-person standard deviation (SDw) in plasma glucose response was analysed both during and 1 h after exercise using the two visits per participant most closely matched by pre-exercise plasma glucose level. When the two closest matched visits per individual were included for analysis, mean (±SD) change in plasma glucose level was -1.8± 1.1 mmoL/L during exercise and -0.6± 1.0 mmoL/L during recovery, with the SDw of these changes being 0.5 mmol (95% CI 0.2, 0.8) during exercise and 0.8 mmoL/L (95% CI 0.4, 1.3) during recovery. The median intra-individual difference in plasma glucose level change was 0.3 mmoL/L [IQR 0.1, 0.7] during exercise and 0.8 mmoL/L [IQR 0.4, 1.0] during recovery. Within-person plasma glucose responses to moderate-intensity exercise may be reproducible under fasting and basal insulin conditions and similar pre-exercise plasma glucose levels. This finding may assist the design of future studies investigating both the reproducibility of glycaemic responses to exercise and blood glucose management for individuals with type 1 diabetes.

NIA Coordinated Analysis of Dynamic Socioemotional Experiences and Well-Being during the Pandemic

We conducted a coordinated analysis of eight longitudinal studies with data collected during the COVID-19 pandemic. Our overarching aim was to examine within-person fluctuations in health and well-being during the pandemic that may differ across the adult lifespan. The studies are from different regions of the U.S. with data collected during different periods of the pandemic. These studies sampled heterogenous age groups, used diverse methods, and were harmonized on constructs. Four longitudinal studies (Notre Dame Study of Health & Well-being, Within-Family Differences Study, Social Relations Study, and the Einstein Aging Study [EAS] Covid Telephone Interviews) and four intensive, microlongitudinal studies (Daily Experience and Well-being Study, Daily COVID-19 Spring, Daily COVID-19 Fall, EAS), with data collected between March 2020 and August 2021 were analyzed. In three studies, older adults were consistently less variable (i.e., lower within-person standard deviation) in negative emotional well-being such as negative affect and depressive symptoms compared to younger adults. In four studies older adults were also less variable in stress. Evidence of better outcomes associated with social interactions was found in three studies, where within-person variability in social interactions was positively correlated with variability in positive affect across age. These findings point toward the complexities of dynamic socioemotional experiences that unfold across historical periods and across the lifespan. These within-person fluctuations could be used as a benchmark to examine long-term trajectories of well-being.

Substantial Intra-Individual Variability in Post-Prandial Time to Peak in Controlled and Free-Living Conditions in Children with Type 1 Diabetes.

The optimal time to bolus insulin for meals is challenging for children and adolescents with type 1 diabetes (T1D). Current guidelines to control glucose excursions do not account for individual differences in glycaemic responses to meals. This study aimed to examine the within- and between-person variability in time to peak (TTP) glycaemic responses after consuming meals under controlled and free-living conditions. Participants aged 8–15 years with T1D ≥ 1 year and using a continuous glucose monitor (CGM) were recruited. Participants consumed a standardised breakfast for six controlled days and maintained their usual daily routine for 14 free-living days. CGM traces were collected after eating. Linear mixed models were used to identify within- and between-person variability in the TTP after each of the controlled breakfasts, free-living breakfasts (FLB), and free-living dinners (FLD) conditions. Thirty participants completed the study (16 females; mean age and standard deviation (SD) 10.5 (1.9)). The TTP variability was greater within a person than the variability between people for all three meal types (between-person vs. within-person SD; controlled breakfast 18.5 vs. 38.9 min; FLB 14.1 vs. 49.6 min; FLD 5.7 vs. 64.5 min). For the first time, the study showed that within-person variability in TTP glycaemic responses is even greater than between-person variability.

Contribution of 20-year body mass index and waist circumference history to poor cardiometabolic health in overweight/obese and normal weight adults: A cohort study

Background and aimsWe investigated the associations of 20-year body mass index (BMI) and waist circumference (WC) histories with risk of being 1) metabolically unhealthy overweight/obese (MUOO) vs metabolically healthy overweight/obese (MHOO) and 2) metabolically unhealthy normal weight (MUNW) vs metabolically healthy normal weight (MHNW). Methods and resultsParticipants comprised 3018 adults (2280 males; 738 females) with BMI and WC measured, every ~5 years, in 1991–1994, 1997–1999, 2002–2004, 2007–2009, and 2012–2013. Mean age in 2012–2013 was 69.3 years, with a range of 59.7–82.2 years. Duration was defined as the number of times a person was overweight/obese (or centrally obese) across the 5 visits, severity as each person's mean BMI (or WC), and variability as the within-person standard deviation of BMI (or WC). At the 2013–2013 visit, participants were categorised based on their weight (overweight/obese or normal weight; body mass index (BMI) ≥25 kg/m2) and health status (healthy or unhealthy; two or more of hypertension, low high-density lipoprotein cholesterol, high triglycerides, high glucose, and high homeostatic model assessment of insulin resistance). Logistic regression was used to estimate associations with the risk of being MUNW (reference MHNW) and MUOO (reference MHOO) at the last visit. BMI and WC severity were each related to increased risk of being unhealthy, with estimates being stronger among normal weight than overweight/obese adults. The estimates for variability exposures became null upon adjustment for severity. Individuals who were overweight/obese at all 5 time points had a 1.60 (0.96–2.67) times higher risk of being MUOO than MHOO compared to those who were only overweight/obese at one (i.e., the last) time point. The corresponding estimate for central obesity was 4.20 (2.88–6.12). Greater duration was also related to higher risk of MUNW than MHNW. ConclusionBeing overweight/obese yet healthy seems to be partially attributable to lower exposure to adiposity across 20 years of adulthood. The results highlight the importance of maintaining optimum and stable BMI and WC, both in adults who become and do not become overweight/obese.

The Statistical Specificity of Emotion Dynamics in Borderline Personality Disorder.

Persons with borderline personality disorder (BPD) experience heightened emotional instability. Different components underlie instability, and the relation between instability and well-being could be confounded by average emotionality and within-person standard deviation across emotional states, reflecting variability. Therefore, the goal was to examine which pattern of emotion dynamics parsimoniously captures the emotional trajectories of persons with BPD. Forty persons with BPD, 38 clinical controls in a major depressive episode, and 40 healthy controls rated the intensity of their emotions 10 times a day for 1 week. After correction for differences in average emotionality, persons with BPD showed heightened emotional instability compared to both control groups. When additionally correcting for emotional variability, the authors found that instability indices did not differ between groups anymore. This shows that persons with BPD differ from control groups in the magnitude of emotional deviations from the emotional baseline, and not necessarily in the degree of abruptness of these deviations.

Effect of Handwashing on Skin Carotenoid Measurements Using Pressure-Mediated Reflectance Spectroscopy

Abstract Objectives To determine whether washing hands with soap and water significantly affects skin carotenoid measurements in healthy adults. Hypotheses: Washing hands with soap and water does not significantly affect mean skin carotenoid scores or variability of skin carotenoid scores in healthy adults. Methods A cross-sectional study was conducted with 30 participants that were recruited by convenience. Subjects completed a brief dietary survey before measurements. Skin carotenoid scores (SCS) on the nondominant index finger were obtained using pressure-mediated reflectance spectroscopy (Veggie Meter) at baseline and after each of 3 rounds of handwashing. Participants washed their hands with soap and water for 20–30 seconds and hands were dried completely. The mean and standard deviation (SD) of the 3 SCS measured at each timepoint were analyzed with repeated-measures ANOVA (α = 0.05). To simulate a usual study, the mean changes between baseline SCS and SCS after round 1 were analyzed with a paired sample t-test (α = 0.05). Results Participants included 3 (10%) males and 27 (90%) females, ranging in age from 19–60. Participants identified themselves as “white” (73%), “black or African American” (7%) and “Asian” (20%). Among these groups, 17% identified as “Hispanic or Latina/Latino”. Mean SCS for each timepoint (baseline, after round 1, after round 2, and after round 3) were not significantly different over the handwashing cycles (P = 0.312). Similarly, the within-person standard deviations for all timepoints remained fairly constant, as there was no significant change throughout the study (P = 0.978). The mean SCS before handwashing was 264.24 ± 18.14 and was 261.14 ± 17.89 after round 1. This showed that while SCS values declined slightly when participants washed their hands, the change was not significant (P = 0.416). Conclusions The SCS of the participants in this study were not significantly affected by handwashing. It is important that the instrument remains clean between measures in order to get the most accurate readings, thus, ensuring that hands are clear of dirt or ink is a vital component of maintaining this accuracy. Asking participants to clean their hands before measurement with the Veggie Meter will not detract from their “true” SCS. Funding Sources Funded in part by Indiana University.

0360 Neighborhood Disadvantage is Associated with Lower Quality Sleep and More Variability in Weeknight Sleep Duration Among Urban Adolescents

Abstract Introduction Differential social and contextual environments may contribute to adolescent sleep disparities. Yet, most prior studies are limited to self-reported sleep data, and the actigraphic studies of sleep are not conducted at a national level, thus limiting the variation in neighborhood contexts. This study examined the association between neighborhood disadvantage and actigraphic assessment of adolescent sleep. Methods Participants (682 adolescents, mean age 15.4 years) were racially/ethnically diverse (44% Black, 26% Hispanic, 17% White, 14% other race/ethnicity), sampled from 20 large US cities in the Fragile Families and Child Wellbeing Study. Neighborhood disadvantage was calculated from American Community Survey 2015 census data using the Standardized Neighborhood Deprivation Index (SNDI), consolidating five variables (proportion of female-headed households, public assistance recipients, households in poverty, adults without high school degrees, and unemployed) into an index. SNDI quartiles 1-3 fell below national averages of SNDI variables (“most disadvantaged”) and were compared to quartile 4 (“least disadvantaged”). Sleep indicators (duration, quality, and timing) were measured over ≥5 nights using wrist-worn accelerometers. Separate multilevel models estimated differences in sleep indicators, adjusting for weekday/weekend and summer/school year. General linear models used within-person standard deviations of sleep indicators (controlling for number of days) to test for associations between neighborhood disadvantage and consistency of weeknight sleep patterns. Models adjusted for individual-level sociodemographic covariates (age, sex, race/ethnicity, household income, caregiver education, and family structure). Results In fully adjusted models, adolescents living in more disadvantaged neighborhoods spent more time awake after falling asleep (4.0 minutes/night, p<0.05), spent greater percentage of nighttime sleep intervals awake (1%, p<.01), and had less consistent sleep duration (11.7% higher standard deviation, p<.05). Sleep duration and timing did not differ across neighborhood groups. Conclusion Living in more disadvantaged neighborhoods is associated with lower quality adolescent sleep; more research is needed to identify causal mechanisms. Support Research was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) of the National Institutes of Health (NIH), award numbers R01HD073352 (PI: Hale), R01HD36916, R01HD39135, and R01 HD40421, and private foundations. The content is the responsibility of the authors and does not represent official NIH views.

Sample size re-estimation in crossover trials: application to the AIM HY-INFORM study

BackgroundCrossover designs are commonly utilised in randomised controlled trials investigating treatments for long-term chronic illnesses. One problem with this design is its inherent repeated measures necessitate the availability of an estimate of the within-person standard deviation (SD) to perform a sample size calculation, which may be rarely available at the design stage of a trial. Interim sample size re-estimation designs can be used to help alleviate this issue by adapting the sample size mid-way through the trial, using accrued information in a statistically robust way.MethodsThe AIM HY-INFORM study is part of the Informative Markers in Hypertension (AIM HY) Programme and comprises two crossover trials, each with a planned recruitment of 600 participants. The objective of the study is to test whether blood pressure response to first line antihypertensive treatment depends on ethnicity. An interim analysis is planned to reassess the assumptions of the planned sample size for the study. The aims of this paper are: (1) to provide a formula for sample size re-estimation in both crossover trials; and (2) to present a simulation study of the planned interim analysis to investigate alternative within-person SDs to that assumed.ResultsThe AIM HY-INFORM protocol sample size calculation fixes the within-person SD to be 8 mmHg, giving > 90% power for a primary treatment effect of 4 mmHg. Using the method developed here and simulating the interim sample size reassessment, if we were to see a larger within-person SD of 9 mmHg at interim, 640 participants for 90% power 90% of the time in the three-period three-treatment design would be required. Similarly, in the four-period four-treatment crossover design, 602 participants would be required.ConclusionsThe formulas presented here provide a method for re-estimating the sample size in crossover trials. In the context of the AIM HY-INFORM study, simulating the interim analysis allows us to explore the results of a possible increase in the within-person SD from that assumed. Simulations show that without increasing the planned sample size of 600 participants, we can reasonably still expect to achieve 80% power with a small increase in the within-person SD from that assumed.Trial registrationClinicalTrials.gov, NCT02847338. Registered on 28 July 2016.

Response.

Dear Editor-in-Chief, We believe that Loucks (1) has inaccurately represented our randomized controlled trial (RCT) designed to test the effects of 3 months of controlled exercise and diet at varying degrees of energy deficit on the induction of menstrual disturbances (MD) (2). Like Bullen et al. (3), we studied 35 previously untrained, eumenorrheic women who were screened to rule out existing organic, endocrine, and psychological causes of MD. Inclusion criteria included two screening cycles and one baseline eumenorrheic cycle with no MD as confirmed with serum (progesterone) and urinary (luteinizing hormone, estrogen, progesterone) measures. Our design allowed for a dose–response analysis with a control and three non-overlapping energy deficit groups. We demonstrated a dose–response relationship between the percent energy deficit and the incidence of MD (2). We confirmed this dose–response relationship in a follow-up analysis (4) where energy balance data were reanalyzed as “energy availability” in a manner similar to Loucks (5). We reported overall significant declines in T3 and IGF-1 with energy deficiency and weight loss relative to our weight-stable exercising control group (2). Dose–response–related changes in metabolic hormones, but not body weight, were demonstrated by Loucks’ 5-d studies, but notably all participants were not exposed to all treatments (semi-cross over design), and the data were analyzed using single-sided, one sample t-tests, providing more power in a single direction (5). As such, the assertion that our 3-month RCT should produce similar dose–response relationships in endocrine biomarkers between our deficit groups should be considered in light of several factors: 1) our RCT was not powered to detect differences among deficit groups in biomarkers or urinary E2, it was powered to detect MD as per our hypothesis of a dose–response relationship between MD and energy deficiency; 2) sources of variability affecting endocrine biomarkers include exercise training effects, the different combinations of diet and exercise among groups to achieve the prescribed energy deficit, individual variability in compensatory reductions in weight, body fat, and RMR (6); and 3) subject compliance to the fed diet outside the two supervised daily meals. These factors are more easily accounted for over 5 d as in Loucks et al. (5) than over 3 months. We reject Loucks’ suggestion that our findings reflect age-related menstrual instability. Any predisposition to MD due to nonintervention-related causes was spread evenly among groups given our RCT design. The stability of our subjects’ three preintervention cycle lengths is demonstrated by a within-person standard deviation of 1.2 d. Our intervention induced significantly more MD as energy deficiency increased, that is, 35% of cycles in up to 88% of women, whereas our exercising control group experienced MD in 16% of cycles in up to 13% of the subjects. In summary, we have demonstrated dose–response relations between energy deficiency and MD in two different articles from the same RCT (2,4). We have not observed a threshold effect of energy availability in these analyses, and we do not support the assertion that a critical threshold of energy availability is associated with MD in exercising women. Nancy I. Williams Mary Jane De Souza Department of Kinesiology Women’s Health and Exercise Laboratory Penn State University University Park, PA

Assessing meaningful within-person variability in Likert-scale rated personality descriptions: An IRT tree approach.

Personality researchers and clinical psychologists have long been interested in within-person variability in a given personality trait. Two critical methodological challenges that stymie current research on within-person variability are separating meaningful within-person variability from (a) true differences in trait level; and (b) careless responding (or person unreliability). To partly avoid these issues, personality researchers commonly only study within-person variability in personality states over time using the standard deviation (SD) across repeated measurements of the same items (typically across days)-a relatively resource-intensive approach. In this article, we detail an approach that allows researchers to measure another type of within-person variability. The described approach utilizes item-response theory (IRT) on the basis of Böckenholt's (2012) three-process model, and extracts a meaningful variability score from Likert-ratings of personality descriptions that is distinct from directional (trait) responding. Two studies (N = 577; N = 120-235) suggest that IRT variability generalizes across traits, has high split-half reliability, is not highly correlated with established indices of IRT person unreliability for directional trait responding, and correlates with within-person SDs from personality inventories and within-person SDs in a diary study with repeated measurements across days 20 months later. The implications and usefulness of IRT variability from personality descriptions as a conceptually clarified, efficient, and feasible assessment of within-person variability in personality ratings are discussed. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

On Standardizing Within-Person Effects: Potential Problems of Global Standardization

Person-mean centering has been recommended for disaggregating between-person and within-person effects when modeling time-varying predictors. Multilevel modeling textbooks recommended global standardization for standardizing fixed effects. An aim of this study is to evaluate whether and when person-mean centering followed by global standardization can accurately estimate fixed-effects within-person relations (the estimand of interest in this study) in multilevel modeling. We analytically derived that global standardization generally yields inconsistent (asymptotically biased) estimates for the estimand when between-person differences in within-person standard deviations exist and the average within-person relation is nonzero. Alternatively, a person-mean-SD standardization (P-S) approach yields consistent estimates. Our simulation results further revealed (1) how misleading the results from global standardization were under various circumstances and (2) the P-S approach had accurate estimates and satisfactory coverage rates of fixed-effects within-person relations when the number of occasions is 30 or more (in many conditions, performance was satisfactory with 10 or 20 occasions). A daily diary data example, focused on emotional complexity, was used to empirically illustrate the approaches. Researchers should choose standardization approaches based on theoretical considerations and should clearly describe the purpose and procedure of standardization in research articles.

A novel standardised side hop test reliably evaluates landing mechanics for anterior cruciate ligament reconstructed persons and controls

ABSTRACT We propose a novel one-leg standardised rebound side-hop test (SRSH) specifically designed for detailed analysis of landing mechanics. Anterior cruciate ligament reconstructed persons (ACLR, n = 30) and healthy-knee controls (CTRL, n = 30) were tested for within-session and test-retest (CTRL only, n = 25) reliability and agreement. Trunk, hip and knee angles and moments in sagittal, frontal, and transversal planes during landing, including time to stabilisation (TTS), were evaluated using intra-class correlations (ICCs), average within-person standard deviations (SW) and minimal differences. Excellent within-session reliability were found for angles in both groups (most ICCs > 0.90, SW ≤ 5°), and excellent to good for moments (most ICCs > 0.80, SW ≤ 0.34 Nm/kg). Only knee internal rotation moment showed poor reliability (ICC < 0.4). Test-retest results were excellent to fair for all angles and moments (ICCs 0.47–0.91, SW < 5° and ≤ 0.25 Nm/kg), except for peak trunk lateral bending angle and knee internal rotation moment. TTS showed excellent to fair within-session reliability but poor test-retest results. These results, with a few exceptions, suggest promising potential of evaluating landing mechanics during the SRSH for ACLR and CTRL, and emphasise the importance of joint-specific movement control variables in standardised tasks.

Short‐term change and prediction of suicidal ideation among adolescents: a daily diary study following psychiatric hospitalization

Our understanding of suicidal ideation (SI) and its risk precursors is largely informed by studies spanning over wide time intervals (weeks, months, years). Little is known about SI as it occurs in daily lives of individuals at risk for suicide, the extent to which suicidal thoughts are dynamic over short periods of time, and the degree to which theoretically informed risk factors predict near-term SI. Thirty-four adolescents hospitalized due to last-month suicide attempt and/or last-week SI (76% female; ages 13-17) responded to daily surveys sent to their cell phones for four consecutive weeks after discharge (n=652 observations). There was notable variability in day-to-day SI, with half of ideation ratings changing at least one within-person standard deviation from one day to the next. Results of mixed effects models revealed concurrent (same-day), but not short-term prospective (next-day), associations between SI (frequency, duration, urge) and well-established predictors (connectedness, burdensomeness, hopelessness). However, synergistic effects of low connectedness with either high burdensomeness or high hopelessness were reliably associated with more severe same- and next-day suicidal ideation. This study adds to emerging literature indicating that suicidal thoughts fluctuate considerably among individuals at risk for suicide, further extending it by focusing on adolescents in the critical posthospitalization period. Fostering high-risk adolescents' sense of connectedness to others may be an especially promising intervention target. Frequent assessment of SI and its predictors, independently and in combination, could help identify promising predictors of short-term risk and meaningful intervention targets in high-risk teens.

Night-to-Night Sleep Variability in Older Adults With Chronic Insomnia: Mediators and Moderators in a Randomized Controlled Trial of Brief Behavioral Therapy (BBT-I).

Sleep variability is a clinically significant variable in understanding and treating insomnia in older adults. The current study examined changes in sleep variability in the course of brief behavioral therapy for insomnia (BBT-I) in older adults who had chronic insomnia. Additionally, the current study examined the mediating mechanisms underlying reductions of sleep variability and the moderating effects of baseline sleep variability on treatment responsiveness. Sixty-two elderly participants were randomly assigned to either BBT-I or self-monitoring and attention control (SMAC). Sleep was assessed by sleep diaries and actigraphy from baseline to posttreatment and at 3-month follow-up. Mixed models were used to examine changes in sleep variability (within-person standard deviations of weekly sleep parameters) and the hypothesized mediation and moderation effects. Variabilities in sleep diary-assessed sleep onset latency (SOL) and actigraphy-assessed total sleep time (TST) significantly decreased in BBT-I compared to SMAC (Pseudo R2 = .12, .27; P = .018, .008). These effects were mediated by reductions in bedtime and wake time variability and time in bed. Significant time × group × baseline sleep variability interactions on sleep outcomes indicated that participants who had higher baseline sleep variability were more responsive to BBT-I; their actigraphy-assessed TST, SOL, and sleep efficiency improved to a greater degree (Pseudo R2 = .15 to .66; P < .001 to .044). BBT-I is effective in reducing sleep variability in older adults who have chronic insomnia. Increased consistency in bedtime and wake time and decreased time in bed mediate reductions of sleep variability. Baseline sleep variability may serve as a marker of high treatment responsiveness to BBT-I. ClinicalTrials.gov, Identifier: NCT02967185.

Abstract 128: Visit-to-visit Variability of Systolic BP and Renal Outcomes in the SPRINT Trial

Increased visit-to-visit variability (VVV) in systolic blood pressure is a known predictor of adverse CV events &amp; in diabetics, is associated with higher risk of incident albuminuria &amp; chronic kidney disease. However, the impact of VVV in SBP on renal outcomes in the absence of diabetes is unknown. We investigated the association between VVV in SBP &amp; adverse CVE &amp; renal events among non-diabetic participants in SPRINT cohort. Methods: Primary exposure was quartile of within-person standard deviation of systolic blood pressure (SDBP). Primary outcomes 1) primary composite CV outcome from SPRINT study, 2) primary SPRINT renal outcome among those without CKD 3) incident albuminuria among those with &amp; without CKD. We compared covariates by SDBP quartile, using ANOVA or chi-square tests. We fit incremental Cox hazards models to examine associations between SDBP &amp; events. We performed sensitivity analyses for # visits in all models. Results: Among 9361 participants, 8589 (92%) met inclusion criteria &amp; comprised the primary analytic sample. The mean SBP across all quartiles was similar (137 - 141 mmHg). There was no association between quartile of SDBP and the primary composite cardiovascular outcome. There was a significant association between quartile of SDBP and incident CKD among those without baseline CKD. Among 3350 participants without baseline CKD and 942 participants with CKD, higher VVV in SBP was independently associated with increased risk of incident albuminuria, regardless of baseline CKD status. This association was robust after adjustment for the number of visits. The interaction between SDBP and the primary intervention was not statistically significant in the no CKD (p=0.11) or CKD groups (p=0.93). Discussion: In this post-hoc analysis of SPRINT, we found that higher VVV in SBP is associated with greater risk of incident albuminuria among non-diabetic adults with and without baseline CKD. This association remained significant after adjustment for numerous potential confounders across follow-up. Our analysis demonstrates a significant association between VVV of SBP and incident albuminuria in patients with and without baseline CKD. This novel finding in an exclusively non-diabetic, hypertensive population deserves further investigation.

High wage workers and high wage peers

This paper investigates the effect of coworker characteristics on wages, measured by the average person effect of coworkers in a wage regression. The effect of interest is identified from within-firm changes in workforce composition, controlling for person effects, firm effects, and sector-specific time trends. My estimates are based on a linked employer employee dataset for the population of workers and firms of the Italian region of Veneto for years 1982-2001. I find that a 0.1 increase in the average labour market value of coworkers’ skills (which is around one within-person standard deviation) is associated with a 3.6 percent wage premium. I also find that a sizeable share of the wage variation previously explained by unobserved individual and firm heterogeneity may be due to variation in coworker skills. An event-type study, a Placebo exercise and a series of heterogeneity analyses lend credibility to the baseline results. I also evaluate the role of the spillover effects for wage differentials between specific groups of workers. I find that around 12 percent of the gender wage gap and 10 to 16 percent of the immigrant wage gap can be explained by differences in coworker characteristics.

Intrapersonal variability in interpersonal perception in romantic relationships: Biases and accuracy

We examined whether intrapersonal variability in the perception of partner’s behavior, perception spin, was related to partner’s intrapersonal variability in behavior, behavioral spin, and was associated with biases in the perception of negative affect. Ninety-three cohabiting couples reported their perceptions of partner’s affect and partner’s communal and agentic behavior in interactions with each other for 20 days. Perception spin was calculated as the within-person standard deviation of perception scores across interactions. Spin in the perception of the partner was associated with the partner’s behavioral spin. Participants with higher perception spin overestimated their partner’s negative affect and more strongly assumed that their partner’s affect was similar to their own negative affect. Thus, perception spin is an individual difference variable that reflects in part the extent of variability in the partner’s behavior, but higher spin also indicates distortions in perceptions of others.

ADHD Symptoms in Adolescents’ Everyday Life: Fluctuations and Symptom Structure Within and Between Individuals

Objective: This study investigated whether self-reported ADHD symptoms fluctuate substantially within adolescents from day to day, and examined the underlying symptom factor structure on a within- and between-person level. Method: Adolescents (N = 166) rated their ADHD symptoms over the phone on eight consecutive evenings (total ratings: n = 1,264). Results: ADHD symptoms showed substantial fluctuations within adolescents from day to day, as indicated by within-person standard deviations and intraclass correlation coefficients. Both a two-level factor model with three correlated factors (inattention, hyperactivity, impulsivity) and a two-level bifactor model with a general ADHD symptom factor and a specific inattention factor provided acceptable to good accounts of the structure underlying daily ADHD symptom ratings on the between- and the within-person level. Conclusion: The study demonstrates that adolescents’ ADHD symptoms fluctuate from day to day and highlights the need for intensive diagnostic processes with repeated symptom assessments and interventions that address symptom fluctuations.