Prediction Accuracy Measures for a Nonlinear Model and for Right-Censored Time-to-Event Data

This article develops a pair of new prediction summary measures for a nonlinear prediction function with right-censored time-to-event data. The first measure, defined as the proportion of explained variance by a linearly corrected prediction function, quantifies the potential predictive power of the nonlinear prediction function. The second measure, defined as the proportion of explained prediction error by its corrected prediction function, gauges the closeness of the prediction function to its corrected version and serves as a supplementary measure to indicate (by a value less than 1) whether the correction is needed to fulfill its potential predictive power and quantify how much prediction error reduction can be realized with the correction. The two measures together provide a complete summary of the predictive accuracy of the nonlinear prediction function. We motivate these measures by first establishing a variance decomposition and a prediction error decomposition at the population level and then deriving uncensored and censored sample versions of these decompositions. We note that for the least square prediction function under the linear model with no censoring, the first measure reduces to the classical coefficient of determination and the second measure degenerates to 1. We show that the sample measures are consistent estimators of their population counterparts and conduct extensive simulations to investigate their finite sample properties. A real data illustration is provided using the PBC data. Supplementary materials for this article are available online. An R package PAmeasures has been developed and made available via the CRAN R library. Supplementary materials for this article are available online.</p

Table_1_Meta-analysis of the diagnostic value of 18F-FDG PET/CT in the recurrence of epithelial ovarian cancer.docx

BackgroundOvarian cancer is the leading cause of cancer-related death among gynecologic malignancies. With much evidence suggesting that 18F-FDG PET/CT may be an excellent imaging test for the diagnosis of epithelial ovarian cancer recurrence, we conducted a systematic review and meta-analysis to summarize relevant studies and evaluate the accuracy and application value of 18F-FDG PET/CT in the diagnosis of recurrence of epithelial ovarian cancer.Materials and methodsClinical trials of 18F-FDG PET/CT for the diagnosis of recurrence of epithelial ovarian cancer were systematically searched in PubMed, Embase, Cochrane Library, Web of Science and OVID database. The relevant literature was searched until May 22, 2022. Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) was used to evaluate the quality of the included original studies, and the meta-analysis was performed using a bivariate mixed-effects model and completed in Stata 15.0.ResultsA total of 17 studies on 18F-FDG PET/CT for the diagnosis of epithelial ovarian cancer recurrence were included in this systematic review, involving 639 patients with epithelial ovarian cancer. Meta-analysis showed that the sensitivity, specificity and area under the curve of 18F-FDG PET/CT for the diagnosis of epithelial ovarian cancer recurrence were 0.88 (95% CI: 0.79 - 0.93), 0.89 (95% CI: 0.72 - 0.96) and 0.94 (95% CI: 0.91- 0.96), respectively. Subgroup analysis showed higher diagnostic efficacy in prospective studies than in retrospective studies, and no significant publication bias was observed in Deeks’ funnel plot, with sensitivity analysis revealing the stability of results. Meta regression shows that the heterogeneity of this study comes from study type.Conclusion18F-FDG PET/CT has good diagnostic value in the recurrence of epithelial ovarian cancer.</p

Data_Sheet_1_Temporal-spatial analysis of a foot-and-mouth disease model with spatial diffusion and vaccination.pdf

Foot-and-mouth disease is an acute, highly infectious, and economically significant transboundary animal disease. Vaccination is an efficient and cost-effective measure to prevent the transmission of this disease. The primary way that foot-and-mouth disease spreads is through direct contact with infected animals, although it can also spread through contact with contaminated environments. This paper uses a diffuse foot-and-mouth disease model to account for the efficacy of vaccination in managing the disease. First, we transform an age-space structured foot-and-mouth disease into a diffusive epidemic model with nonlocal infection coupling the latent period and the latent diffusive rate. The basic reproduction number, which determines the outbreak of the disease, is then explicitly formulated. Finally, numerical simulations demonstrate that increasing vaccine efficacy has a remarkable effect than increasing vaccine coverage.</p

Mean value comparison of Scenarios 1 and 2.

Mean value comparison of Scenarios 1 and 2.</p

Hypothesis testing—Main variables of Scenario 1.

Hypothesis testing—Main variables of Scenario 1.</p

Map of keywords of groups on substandard drugs during 1985–2019.

Map of keywords of groups on substandard drugs during 1985–2019.</p

Countries in which substandard and falsified medicinal products have been reported to WHO, 2013–2017[1].

Countries in which substandard and falsified medicinal products have been reported to WHO, 2013–2017[1].</p

CV results of scenario 1 & 2.

CV results of scenario 1 & 2.</p

Current state and limiting factors of wheat yield at the farm level in Hubei Province

Longitudinal wheat yields in China have declined in recent times due to climate change, more frequent natural disasters, and suboptimal agronomic management. To date, it has been unclear which factors have predominated yield penalties realised hitherto in Hubei Province. This study aimed to identify key factors limiting wheat production across systems and agroecological regions, and provide a basis for increasing crop production while engendering food security. Survey data from 791 households in Hubei Province were analyzed using descriptive statistics and logistic regression. Significant spatial heterogeneity in average wheat yields was observed, with the Jianghan Plain region having significantly lower yields compared with the northwest region (yield gap: 1,125 kg·hm−2). Dryland wheat had higher average yields than rice-rotation wheat (yield gap: 134 to 575 kg·hm−2). Socioeconomic factors, cultivation management measures, and environmental factors contributed differently to yield differences. Input costs and economic benefits were key social factors influencing wheat production. Variation in management were mainly attributed to planting methods, while soil fertility and climatic factors limited yields in some regions. In the northwest, low soil fertility and susceptibility to drought and high temperatures had greater influence on yields. In the Jianghan Plain, soil waterlogging and erosion were key challenges. Waterlogging increased the probability of low yields by 8.6 times, while severe soil erosion increased probability of yield loss by a factor of almost five. Low-yield farms in the Jianghan Plain were 21% higher than those in the northwest. Extreme weather events also contributed to low yields in the Jianghan Plain. We note significant potential for increasing farm-level wheat production in Hubei Province, with large existing differences across agro-ecological regions and planting modes. Differences in cultivation practices was a major driving factor of yield gaps between planting modes, while soil fertility and meteorological disasters drive regional yield differences. These results have implications for those aspiring to narrow the yield gap across regions and increase production of cereal crops.</p

CV indicator and criteria.

CV indicator and criteria.</p