Category: Statistics

Psychol Methods. 2026 May 18. doi: 10.1037/met0000834. Online ahead of print.

ABSTRACT

Although previous research has described that intervention effects vary across replication studies, less effort has been devoted to identifying causes of this effect heterogeneity with regard to differences in study implementations. However, knowing in which way study characteristics (such as population, measurement instrument, setting, or treatment implementation) impact the study results may not only help to better infer the impact of research practices but also provide evidence for theory building. Causal effects can be easily identified if all study characteristics but the one under investigation are kept constant across two studies. This is, however, not always possible in practice and unintended differences between the studies to be compared may confound the relationship of the study characteristic of interest and the treatment effect. In this article, we present a statistical approach for identifying effects of study characteristics on study-specific treatment effects from randomized experiments in cases in which unintended differences in study implementation across studies cannot be prevented. We present formal definitions of the causal effects of interest, identification assumptions, and derive respective causal estimands. The assumptions can more likely be fulfilled in prospective replication studies or many-lab studies, where researchers have more control over design and measurement of covariates in both studies. We also provide ways to test the assumptions and illustrate consequences of not meeting the assumptions. The approach is illustrated using an empirical example on the imagined intergroup contact effect in social psychology. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

PMID:42149494 | DOI:10.1037/met0000834

J Infect Dis. 2026 May 18:jiag193. doi: 10.1093/infdis/jiag193. Online ahead of print.

ABSTRACT

Infectious disease trials have long used ordinal outcomes, or ranked categorical scales, to capture the full spectrum of response to an intervention. We review 2 summary statistics for ordinal outcomes: the proportional odds ratio (pOR) and the win probability. The pOR asks: How much more likely is a treated participant to be in an improved category compared with control? The win probability asks: In a random treatment-control pair, what is the chance the treated participant fares better? We also introduce visual companions, the stacked-bar chart and bubble plot, to make ordinal trial results more accessible and interpretable.

PMID:42149490 | DOI:10.1093/infdis/jiag193

J Psychopathol Clin Sci. 2026 May 18. doi: 10.1037/abn0001113. Online ahead of print.

ABSTRACT

The stress generation model posits that depression and other psychopathology elevate risk that individuals create or select into stressful life events. Although decades of research support stress generation theory, life stress is inherently challenging to assess and model as an outcome variable, and prior studies follow inconsistent methodological standards. Toward a vision of elevated “next generation” research, we present expert consensus methodological guidelines for conducting stress generation research. A panel of researchers with diverse expertise delineates best practice, acceptable, and nonrecommended methods across 6 areas: stressor operationalizations, assessment, longitudinal study design (including intensive longitudinal design), statistical analysis, openness/transparency, and avoiding stigmatizing language. For example, the review covers modeling stressors as formative variables, statistically comparing effect sizes for predicting independent and dependent stress, and using life stress interviews versus questionnaires, among other methodological concerns pertinent to stress generation research. Following these guidelines will allow future investigators to construct a research base with greater rigor, transparency, and reproducibility, providing a firmer foundation to improve understanding of stress generation. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

PMID:42149474 | DOI:10.1037/abn0001113

Psychol Trauma. 2026 May 18. doi: 10.1037/tra0002167. Online ahead of print.

ABSTRACT

OBJECTIVE: The Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5) characterizes posttraumatic stress disorder (PTSD) by intrusion, avoidance, negative cognition, and hyperarousal symptom clusters. These clusters may reflect distinct underlying pathologies. There is a strong bidirectional relationship between PTSD and sleep disturbances, but sleep’s associations with individual symptom clusters remain unclear. This study examines these relationships and may be the first relating sleep architecture to the negative cognition cluster. We investigated subjective and physiological sleep measures across the spectrum of PTSD symptom cluster severities.

METHOD: This Research Domain Criteria-design study included participants (N = 133) who experienced a Criterion-A trauma within the past 2 years but not the previous month; 68 met PTSD criteria and 65 qualified as resilient or subthreshold PTSD using the Clinician-Administered PTSD Scale for DSM-5. Sleep was assessed via 14-days of sleep diaries and one night of ambulatory polysomnography following an acclimation night. Multiple linear regression models analyzed sleep quality measures (sleep onset latency, total sleep time, sleep midpoint, and wake after sleep onset), while stepwise regression models explored sleep architecture (sleep macroarchitecture, rapid eye movement sleep, and slow-wave sleep microarchitecture).

RESULTS: Sleep quality measures had varying relationships with total PTSD Checklist for DSM-5 and symptom cluster scores. Sleep architecture and rapid eye movement sleep-specific and slow-wave sleep-specific features demonstrated unique relationships with PTSD symptom clusters.

CONCLUSIONS: Findings suggest the utility of dimensional approaches, potential symptom-specific intervention targets, and highlight possible distinct contributions of sleep in PTSD cluster pathophysiology. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

PMID:42149467 | DOI:10.1037/tra0002167

Int Urol Nephrol. 2026 May 18. doi: 10.1007/s11255-026-05193-2. Online ahead of print.

ABSTRACT

AIM AND OBJECTIVES: This study aimed to evaluate perirenal and epicardial fat thickness and examine their associations with oxidative stress, inflammation, and metabolic markers in pre-dialysis CKD patients (diabetic and non-diabetic) compared with healthy controls.

MATERIAL AND METHODS: This cross-sectional study included 90 participants (30 diabetic CKD, 30 non-diabetic CKD, and 30 controls). Perirenal fat thickness was assessed by ultrasonography and epicardial fat thickness by echocardiography. Biochemical parameters including renal function, lipid profile, hs-CRP, malondialdehyde (MDA), and ferric reducing antioxidant power (FRAP) were measured. Statistical analysis was performed using parametric or non-parametric tests based on data distribution, with multivariate regression adjusting for age, sex, and BMI.

RESULTS: DKD patients had significantly higher perirenal (32.1 ± 5.0 mm) and epicardial (8.72 ± 1.89 mm) fat thickness compared to non-DKD patients and controls. DKD patients also exhibited increased oxidative stress (MDA 4.65 ± 3.39 µmol/L) and decreased antioxidant capacity (FRAP 0.25 ± 0.16 mmol/L). The inflammatory marker hs-CRP was significantly elevated in DKD patients [8.53 (12.64) mg/L]. No significant differences were observed in lipid profiles or atherogenic indices between groups; however, visceral adiposity showed significant positive correlations with atherogenic indices.

CONCLUSION: Pre-dialysis CKD patients, particularly those with diabetes, exhibit increased visceral adiposity along with higher oxidative stress and inflammation. Although atherogenic indices were not significantly different between groups, their association with visceral fat suggests a potential role of regional adiposity as a marker of metabolic risk; however, longitudinal studies are required to establish the prognostic significance.

PMID:42149464 | DOI:10.1007/s11255-026-05193-2

Methods Mol Biol. 2026;3031:377-398. doi: 10.1007/978-1-0716-5253-4_29.

ABSTRACT

Shaped by evolution, human skin cells have acquired a remarkable capacity to detect and react to sunlight photons through a wide array of photochemical processes. These reactions trigger intricate intracellular signaling cascades, ultimately resulting in photobiological effects that help regulate skin cell homeostasis. Some of these photobiological responses (also so-called photobiomodulation or low-level light therapy) are capable of initiating profound and beneficial therapeutic effects. To identify the regimes for these light-based therapeutic solutions, one needs to carefully decipher the physical, optical, biological, and chemical conditions that all need to be fulfilled to facilitate such positive photobiological effects. Here, we provide the protocols specifically developed to investigate multidimensional parameter space driving photobiological interactions triggered by light in the cells of human integumentary system. The approach also includes the so-called design of experiment (DoE), a statistical method, which allows for the investigation of multidimensional parameters landscapes. This goes hand in hand with sharing practical tips for the design of light-based devices for experimental work. We illustrate practical applications of our methods and light-based devices by sharing comprehensive experimental datasets, highlighting both the robustness and reproducibility of the results.

PMID:42149463 | DOI:10.1007/978-1-0716-5253-4_29

Ophthalmic Physiol Opt. 2026 May 18. doi: 10.1007/s44402-026-00093-5. Online ahead of print.

ABSTRACT

PURPOSE: To evaluate systematically the effect of different concentrations of atropine eye drops on accommodative amplitude and binocular visual function in children and adolescents with myopia.

METHODS: A systematic review and meta-analysis of randomised controlled trials was conducted in accordance with PRISMA 2020 guidelines and registered in PROSPERO (registration number: CRD420261297760). PubMed, Web of Science and Scopus were searched up to January 15, 2025. Eligible studies compared atropine eye drops (0.01-1%) with placebo, single-vision correction or no treatment and reported accommodative or binocular vision outcomes. The primary outcome was the change in accommodative amplitude. Secondary outcomes included accommodative lag, stereoacuity, heterophoria and fusional vergence. Mean differences (MD) with 95% confidence intervals (CI) were pooled using fixed- or random-effects models based on heterogeneity.

RESULTS: Thirteen randomised controlled trials were included, most of which were conducted in Asian populations. Low-dose atropine (0.01%) was associated with a small but statistically significant reduction in accommodative amplitude (MD: -0.84 D, 95% CI: -1.50 to -0.18), with substantial heterogeneity and no consistent effects at individual follow-up time points. Intermediate concentrations (0.02-0.03%) showed variable and heterogeneous effects. Atropine 0.05% produced a consistent and clinically meaningful reduction in accommodative amplitude (MD: -1.96 D, 95% CI: -2.36 to -1.57) and measurable changes in binocular parameters. Higher concentrations (≥0.1%) resulted in marked cycloplegic effects.

CONCLUSIONS: The effects of atropine on accommodation and binocular visual function are dose-dependent. Low-dose atropine demonstrates a favourable functional safety profile, while higher concentrations are associated with clinically relevant accommodative impairment.

PMID:42149424 | DOI:10.1007/s44402-026-00093-5

Environ Monit Assess. 2026 May 18;198(6):605. doi: 10.1007/s10661-026-15472-1.

ABSTRACT

The development processes of soil are influenced by temperature and precipitation; moreover, changes in soil properties are influenced by land use factors. This study aimed to identify the pattern of changes in climate over 40 years (from 1985-2024) and, concomitantly, the spatial and temporal variabilities in the soil properties of Sylhet, a humid subtropical region of Bangladesh. Soil samples were taken from 8 unions of the Sylhet sadar upazila during 2024 and tested in the laboratory to determine the present status of different soil parameters. The temporal changes in soil properties were assessed by comparing the laboratory-analysed data with soil resource development institute-reported soil data from 2007. The annual maximum temperature during the last 20 years of the study (2005-2024) increased by 0.42°C on average, and the hottest year was 2023. The total annual precipitation sharply decreased by 762.34 mm compared with that in the first 20 years (1985-2004), with continuous below-normal precipitation events (-1270.96 mm to -104.32 mm) from 2018-2023 and high interannual variability. In addition, this study revealed greater spatial variability in soils than temporal variability, which was influenced mainly by inherent soil characteristics such as texture and pH and assumed land management practices. Moderate temporal variability in soil organic carbon and other nutrient availability might be associated with changing climates. These findings on spatial and temporal changes in soil properties are expected to be helpful for guiding future soil and crop management in humid subtropical regions in a better way under changing climates.

PMID:42149408 | DOI:10.1007/s10661-026-15472-1

J Community Genet. 2026 May 18;17(3):63. doi: 10.1007/s12687-026-00899-3.

ABSTRACT

Hemoglobinopathies remain a major public health concern in Tunisia. Effective prevention depends on informed prenatal screening, yet the role of health literacy in screening acceptability is poorly documented in North Africa. This pilot study developed and culturally adapted a 9-item health literacy questionnaire based on Nutbeam’s multidimensional framework and examined its direct and indirect associations, via perceived understanding, with screening acceptability. A cross-sectional pilot study was conducted at the national referral maternity center CHU La Rabta in Tunis with 256 pregnant women aged 18-49 years. The questionnaire was rigorously adapted to Tunisian Arabic dialect through forward-back translation and cognitive debriefing with five pregnant women. Health literacy was assessed using functional, interactive, and critical subscales (1-4 Likert scale). Screening acceptability and perceived understanding to decide were also measured. Data was analyzed with descriptive statistics, reliability testing (Cronbach’s α), Spearman correlations, and bootstrapped mediation analysis. Mean global health literacy was 2.70 ± 0.77 (59.8% in the “high” category). The 9-item scale showed good reliability (Cronbach’s α = 0.826). Interactive literacy scored highest (2.95 ± 0.92), while functional (2.58 ± 0.93) and critical (2.56 ± 1.00) dimensions were lower. The analysis revealed associations consistent with partial mediation: higher health literacy was associated with screening acceptability both directly (c’ = 0.438, p = 0.042) and indirectly through perceived understanding (indirect effect = 0.314, 95% CI 0.128-0.562, p < 0.001), accounting for 41.8% of the total effect. After adjustment for age, education, and residence, global health literacy remained independently associated with screening acceptability (adjusted OR = 1.55, p = 0.041). A brief, culturally adapted health literacy tool proved feasible and reliable in the Tunisian prenatal context. Higher health literacy was associated with greater screening acceptability both directly and indirectly through improved perceived understanding. These findings provide a strong empirical basis for integrating health literacy assessment and targeted literacy-enhancing interventions into Tunisia’s national hemoglobinopathy prevention program.

PMID:42149388 | DOI:10.1007/s12687-026-00899-3

Ann Nucl Med. 2026 May 18. doi: 10.1007/s12149-026-02218-9. Online ahead of print.

ABSTRACT

OBJECTIVE: To compare whole-brain histogram analysis (WBHA) of amyloid-β (Aβ) positron emission tomography (PET) using several magnetic resonance imaging (MRI)-based brain extraction (brain extraction tool [BET]) methods, to evaluate a novel quantitative analysis method, namely the Top 20% Gray and White Matter Ratio (GW-ratio), to determine appropriate thresholds, and to evaluate diagnostic performance in comparison with the Centiloid scale (CL).

METHODS: We analyzed structural MRI, ¹⁸F-flutemetamol amyloid PET images, and dementia severity scores (Global Clinical Dementia Rating [G-CDR] and Mini-Mental State Examination [MMSE]) of 262 participants. For WBHA, BET was performed using structural MRI and three different BET software programs, namely High-Definition-BET (HD-BET), FMRIB Software Library (FSL), and Statistical Parametric Mapping (SPM). Skewness and mode-to-mean ratio (MMR) were measured using brain-extracted PET. The Top 20% Map was generated from SPM BET images, separated into gray and white matter voxels, and their ratio was calculated as the GW-ratio. The CL value was computed using structural MRI. Aβ-negativity or positivity was visually determined.

RESULTS: Skewness from three BET methods was strongly negatively correlated with CL. Skewness (HD-BET) showed the strongest correlation (R = -0.9043). Moreover, the GW-ratio strongly correlated with CL (R = 0.8332), whereas MMR, particularly MMR (FSL) (R = 0.2112), showed poor correlation. All indicators significantly distinguished Aβ-negative from Aβ-positive visuals. CL had the highest area under the curve (AUC, 0.9959), followed by skewness (HD-BET) (0.9927), Top 20% GW-ratio (0.9872), and skewness (SPM) (0.9779), with no statistical difference between CL and skewness (HD-BET) (P = 0.5763). Based on mean and SD values from 118 cognitively unimpaired (G-CDR = 0, MMSE ≥ 28) and visually Aβ-negative participants, 95% cut-off limits for Aβ-negative individuals without dementia symptoms were: CL ≤ 12.9, skewness (HD-BET) ≥ 0.1769, MMR (HD-BET) ≤ 0.9372, skewness (FSL) ≥ 0.1819, MMR (FSL) ≤ 1.9132, skewness (SPM) ≥ -0.0382, MMR (SPM) ≤ 1.1274, and GW-ratio ≤ 0.1079.

CONCLUSION: WBHA using MRI-based BET and GW-ratio showed strong correlations with CL and demonstrated a diagnostic performance comparable to that of CL.

PMID:42149370 | DOI:10.1007/s12149-026-02218-9