Framing Causal Questions in Life Course Epidemiology

We describe the principles of counterfactual thinking in providing more precise definitions of causal effects and some of the implications of this work for the way in which causal questions in life course research are framed and evidence evaluated. Terminology is explained and examples of common life course analyses are discussed that focus on the timing of exposures, the mediation of their effects, observed and unobserved confounders, and measurement error. The examples are illustrated by analyses using singleton and twin cohort data. Expected final online publication date for the Annual Review of Statistics and Its Application, Volume 9 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Post-selection Inference

We discuss inference after data exploration, with a particular focus on inference after model or variable selection. We review three popular approaches to this problem: sample splitting, simultaneous inference, and conditional selective inference. We explain how each approach works and highlight its advantages and disadvantages. We also provide an illustration of these post-selection inference approaches. Expected final online publication date for the Annual Review of Statistics and Its Application, Volume 9 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Score-Driven Time Series Models

The construction of score-driven filters for nonlinear time series models is described, and they are shown to apply over a wide range of disciplines. Their theoretical and practical advantages over other methods are highlighted. Topics covered include robust time series modeling, conditional heteroscedasticity, count data, dynamic correlation and association, censoring, circular data, and switching regimes. Expected final online publication date for the Annual Review of Statistics and Its Application, Volume 9 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Effects of Causes and Causes of Effects

We describe and contrast two distinct problem areas for statistical causality: studying the likely effects of an intervention (effects of causes) and studying whether there is a causal link between the observed exposure and outcome in an individual case (causes of effects). For each of these, we introduce and compare various formal frameworks that have been proposed for that purpose, including the decision-theoretic approach, structural equations, structural and stochastic causal models, and potential outcomes. We argue that counterfactual concepts are unnecessary for studying effects of causes but are needed for analyzing causes of effects. They are, however, subject to a degree of arbitrariness, which can be reduced, though not in general eliminated, by taking account of additional structure in the problem. Expected final online publication date for the Annual Review of Statistics and Its Application, Volume 9 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Optimization of the Water and Fertilizer of Rice in the Cold Field and the Biochar Application Amount Based on RAGA Model

This paper proposes an optimization method based on the RAGA model. Taking rice from a cold area as the research object, this article selects irrigation volume, nitrogen application volume, and biochar application volume as experimental factors, and rice yield, water use efficiency, greenhouse gas emission comprehensive warming potential as influencing indicators. The research design is D311 Field trials by 3 factors of 5 levels of saturation. Hence, we can obtain the data on rice yield, water use efficiency, greenhouse gas emissions and comprehensive warming potential under different levels of water and fertilizer, and biochar application, and regression equations were established respectively. The RAGA model was used to simulate the regression equations. The optimal combination of water and fertilizer, and biochar was obtained as follows: irrigation amount is 7230 m3.hm-2, nitrogen fertilizer application amount is 92.13 kg.hm-2, and biochar application amount is 30 t.hm-2. The optimal rice yield obtained under this combination is 9452.20 kg.hm-2. The water use efficiency is 1.94 kg.m-3, and the comprehensive warming potential of greenhouse gas emissions is 4546.73 kg.hm-2. The combined application of water and fertilizer, and biochar optimized by this model can provide a theoretical basis for achieving high yield, water-saving, and emission reduction of rice in cold areas, and it can also provide a reliable calculation method and idea for solving similar optimization problems in the field of agricultural production.

Do commodity prices incentivize exploration permit application? An explorative study of an anecdotal relation

Do commodity prices drive exploration permit applications? In a recent qualitative study on mineral exploration and risk management in Sweden, a number of respondents representing mineral exploration organizations and governmental agencies expressed how mineral exploration permit applications increase with rising commodity prices. This paper seeks to investigate this alleged correlation quantitatively. In doing so, the study uses time series analysis and ARIMA models to analyze the covariation of applications for exploration permits filed with the Mining Inspectorate of Sweden and annual average copper, lead, zinc, silver, and gold prices in the period 2000 to 2018. Contrary to the anecdotal evidence given by actors in the exploration and mining industry, the paper cannot show any significant covariation between the majority of mineral prices and applications filed. Contrary to expectations, there appear therefore not to be any correlation between copper, lead, silver, and gold prices and the volume of permit applications filed annually. Moreover, the study also shows that the correlation between annual average zinc prices and permit applications appears to be the reverse of what was first believed as the annual change in application volume occurs before the rise or fall in zinc prices.

Effect of Tractor Speed and Spray Application Volume on Severity of Scab at Different Heights in the Canopy of Tall Pecan Trees

Scab (caused by Venturia effusa) is the most important yield-limiting disease of pecan in the southeastern USA. On susceptible cultivars, the disease is managed using fungicides, but spray coverage is an issue in tall trees. In four experiments we used an air-blast sprayer to compare scab severity on fruit at 5.0 to 15.0 m height in trees receiving the same dose of fungicide at 468, 935 and 1871 L/ha at 2.4 and 3.2 km/h (in two additional experiments fungicides were applied at 4.0 km/h @ 470 L/Ha, 4.0 km/h @ 940 L/Ha and 4.0 km/h @ 1100 L/Ha). An air-blast sprayer was used for the applications, which included typical recommended active ingredients (a.i.). Nozzles were selected to provide similar proportions of spray to the upper and lower canopy. The treatments (or subsets thereof) were repeated in 2015 to 2017 on cv. Schley, and in 2017, 2019 and 2020 on cv. Desirable. All treatments reduced scab compared to the control. Overall, there was no consistent difference among the treatments for severity of scab on foliage, immature fruit, or mature fruit at any height in the canopy up to 15.0 m (maximum height sampled). Fungicide applied at 2.4 or 3.2 km/h @ 470 L/ha was as effective at reducing disease as were the higher volumes (sometimes more so). The scab epidemic severity affected control efficacy. Estimated cost and water savings based on faster speed and lower volume were considerable. These preliminary observations indicate no single volume or speed was consistently superior to control scab; this suggests in most seasons, low volumes (higher concentration of a.i.) may be similarly efficacious as high volumes (lower concentration of a.i.) for controlling scab in tall pecan trees, and offer greater resource use efficiency.

Untested Admissions: Examining Changes in Application Behaviors and Student Demographics Under Test-Optional Policies

This study examines a diverse set of nearly 100 private institutions that adopted test-optional undergraduate admissions policies between 2005–2006 and 2015–2016. Using comparative interrupted time series analysis and difference-in-differences with matching, I find that test-optional policies were associated with a 3% to 4% increase in Pell Grant recipients, a 10% to 12% increase in first-time students from underrepresented racial/ethnic backgrounds, and a 6% to 8% increase in first-time enrollment of women. Overall, I do not detect clear evidence of changes in application volume or yield rate. Subgroup analyses suggest that these patterns were generally similar for both the more selective and the less selective institutions examined. These findings provide evidence regarding the potential—and the limitations—of using test-optional policies to improve equity in admissions.

Design and development of a servo-controlled target-oriented robotic micro-dose spraying system in precision weed control

The broadcast spraying method using excessive amounts of pesticides is generally preferred for weed control in agriculture. In this study, a mobile robot was developed and tested on artificial weed targets for a micro-dose spraying system to reduce amount of liquid sprayed for weed control. A prototype mobile robot consisting of a robotic platform, machine vision and steerable spraying unit was constructed and controlled by using LabVIEW software and tested to evaluate the applicability of the spraying system. The greenness method and segmentation algorithm were used to extract artificial weeds from the background. The artificial weed samples were treated according to their coordinates by using a servo-based micro-dose spraying needle nozzle. The experiments were carried out at speeds of 0.42, 0.54, 0.66, 0.78 and 0.90 km h-1 to evaluate the performance of the spraying system under laboratory conditions. The tracking and targeting performances of the mobile spraying system were observed visually. Consumption, deposition and coverage rate experiments were carried out by using graduated cups, filter papers and water-sensitive papers to evaluate the spraying efficiency of the system under 200 kPa of spraying pressure. The results showed that the targeted micro-dose spraying method saved approximately 95% of the application volume compared with the broadcast spraying method. Higher spraying efficiency was determined at the middle locations rather than at the edge locations according to the amount of deposition and coverage rate results. The servo-controlled target-oriented weed control system that was developed was tested experimentally and found to be very efficient.