Search

Product recommendations can benefit consumers' online product search via multiple underlying mechanisms, such as showing products that offer them high value, facilitating navigation on the website, or exposing more product information. However, it is unclear ex ante which is the primary underlying mechanism that drives the benefits of product recommendations to consumers. We conducted a randomized field experiment to estimate the benefits of an item-based collaborative filtering (CF) recommendation system to consumers. We collect unique data on the affinity scores computed by an item-based CF algorithm to develop measures of a product's net value and horizontal (taste) fit for consumers. Our results indicate that product recommendations help consumers search for higher-value products that are lower priced, fit their tastes better, or both. Besides that, we find that the ability to find higher-value products (rather than easy navigation or exposure to more product information) is the primary driver for consumers' higher purchase probabilities under recommendations. We further find a higher benefit of recommendations in product categories with higher price dispersion and heterogeneity in consumers' tastes, providing additional evidence for the lower price and better horizontal fit mechanisms. Finally, we find that when made available, consumers substitute their usage of other search tools on the website with product recommendations. Our findings have important implications for online retailers, policymakers, regulators, and item-based CF recommendation system design. This paper was accepted by D. J. Wu, information systems. Funding: This work was supported by the Public Utility Research Center of the University of Florida, the Hi! PARIS Fellowship, the HEC Foundation, and the Leavey School of Business at Santa Clara University [Grant 102720]. Supplemental Material: Data and the online appendix are available at https://doi.org/10.1287/mnsc.2023.4951. [ABSTRACT FROM AUTHOR]

Target values for 25-hydroxy vitamin D and 1,25(OH)2D or 1,25-dihydroxy vitamin D remain a topic of debate among clinicians. We analysed data collected from December 2012 to April 2020 from two cohorts. Cohort A, comprising 455,062 subjects, was used to investigate the relationship between inflammatory indicators (white blood cell [WBC] count and C-reactive protein [CRP]) and 25(OH)D/1,25(OH)2D. Cohort B, including 47,778 subjects, was used to investigate the connection between 25(OH)D/1,25(OH)2D and mineral metabolism markers (phosphate, calcium, and intact parathyroid hormone [iPTH]). Quadratic models fit best for all tested correlations, revealing U-shaped relationships between inflammatory indicators and 25(OH)D and 1,25(OH)2D. Minimal CRP and WBC counts were observed at 1,25(OH)2D levels of 60 pg/mL and at 25(OH)D levels of 32 ng/mL, as well as of 42 ng/mL, respectively. iPTH correlated inversely with both 1,25(OH)2D and 25(OH)D, while phosphate as well as calcium levels positively correlated with both vitamin D forms. Calcium-phosphate product increased sharply when 25(OH)D was more than 50 ng/mL, indicating a possible risk for vascular calcification. Multiple regression analyses confirmed that these correlations were independent of confounders. This study suggests target values for 25(OH)D between 30–50 ng/mL and for 1,25(OH)2D between 50–70 pg/mL, based particularly on their associations with inflammation but also with mineral metabolism markers. These findings contribute to the ongoing discussion around ideal levels of vitamin D but require support from independent studies with data on clinical endpoints. [ABSTRACT FROM AUTHOR]

Introduction: Periostin is a matricellular protein. Elevated serum concentrations of periostin have been reported in patients with various cardiovascular diseases, including heart failure. Patients with end-stage renal disease have a substantially increased risk for cardiovascular diseases. However, there is a lack of clinical studies to clarify the prognostic significance of systemic periostin on all-cause mortality in patients with end-stage renal disease on hemodialysis., Methods: 313 stable end-stage renal disease patients were recruited and followed for 5 years concerning all-cause mortality. At baseline, we collected blood samples and clinical data. Serum periostin concentrations were measured using a certified ELISA., Results: The optimal cut-off value for serum periostin regarding all-cause mortality, calculated through receiver operating characteristic analysis, was 777.5 pmol/L. Kaplan-Meier survival analysis using this cut-off value demonstrated that higher periostin concentrations are linked to higher all-cause mortality (log-rank test: p = 0.002). Subgroup analysis revealed that serum periostin concentrations only affected all-cause mortality in male but not in female patients (p = 0.002 in male patients and p = 0.474 in female patients). Multivariate Cox regression analyses, adjusted for confounding factors, likewise showed that elevated serum periostin concentrations were positively associated with all-cause mortality in male (p = 0.028) but not in female patients on hemodialysis (p = 0.313)., Conclusion: Baseline serum periostin is an independent risk factor for all-cause mortality in male patients with chronic renal disease on hemodialysis., (© 2024 The Author(s). Published by S. Karger AG, Basel.)