Extracting Long-Term Patterns of Population Changes from Sporadic Counts of Migrant Birds

Declines of many North American birds are of conservation concern. Monitoring their population changes has largely depended on formally structured Breeding Bird Surveys, and Migration Monitoring Stations, although some use has been made of lists by birders. For almost 40 years, birders have kept daily counts of migrant landbirds during visits to Seal Island, of Nova Scotia's south tip. Here we present results for several common migrants using day-counts made between August 15 and November 15. Most existing analyses have used linear models to extract trends and other variables from such long-term data sets. Instead we applied Generalized Additive Models (GAMs) to extract the continuous trend functions and patterns of influence of observer number, wind speed, wind direction on count nights and prior nights, and moon phase. The results suggest that GAMs are a powerful way of dealing with such "noisy" data of the sort collected by birders in their recreational pursuits. In addition, it is possible to analyse groups of species (related taxonomically or ecologically) simultaneously with the potential of determining overall more general trends.Seal Island, Generalized additive models, Count data, Overdisperson

Longitudinal variable selection by cross-validation in the case of many covariates

Longitudinal models are commonly used for studying data collected on individuals repeatedly through time. While there are now a variety of such models available (Marginal Models, Mixed Effects Models, etc.), far fewer options appear to exist for the closely related issue of variable selection. In addition, longitudinal data typically derive from medical or other large-scale studies where often large numbers of potential explanatory variables and hence even larger numbers of candidate models must be considered. Cross-validation is a popular method for variable selection based on the predictive ability of the model. Here, we propose a cross-validation Markov Chain Monte Carlo procedure as a general variable selection tool which avoids the need to visit all candidate models. Inclusion of a “one-standard error” rule provides users with a collection of good models as is often desired. We demonstrate the effectiveness of our procedure both in a simulation setting and in a real application.

State-space models' dirty little secrets: even simple linear Gaussian models can have estimation problems

State-space models (SSMs) are increasingly used in ecology to model time-series such as animal movement paths and population dynamics. This type of hierarchical model is often structured to account for two levels of variability: biological stochasticity and measurement error. SSMs are flexible. They can model linear and nonlinear processes using a variety of statistical distributions. Recent ecological SSMs are often complex, with a large number of parameters to estimate. Through a simulation study, we show that even simple linear Gaussian SSMs can suffer from parameter- and state-estimation problems. We demonstrate that these problems occur primarily when measurement error is larger than biological stochasticity, the condition that often drives ecologists to use SSMs. Using an animal movement example, we show how these estimation problems can affect ecological inference. Biased parameter estimates of a SSM describing the movement of polar bears (\textit{Ursus maritimus}) result in overestimating their energy expenditure. We suggest potential solutions, but show that it often remains difficult to estimate parameters. While SSMs are powerful tools, they can give misleading results and we urge ecologists to assess whether the parameters can be estimated accurately before drawing ecological conclusions from their results

The Effect of Cognitive Load and Inhibiting Cues on Triggered Displaced Aggression

Triggered displaced aggression (TDA) is when a provocation, followed by a subsequent provocation, initiates an aggressive response. Research has shown that cognitive load can increase TDA. It has also demonstrated that inhibiting cues can decrease TDA. However, the interaction between cognitive load and inhibiting cues moderating the magnitude of TDA has not yet been studied. Thus, the present experiment investigated the effects of these two variables on TDA. The sample consisted of 80 university students, 59 females and 21 males. The experiment used a 2 (cognitive load high/low) x 2 (inhibiting cues yes/no) factorial design to manipulate cognitive load and inhibiting cues. Following the TDA paradigm procedures, participants were provoked by insulting their performance on a bogus task. They were then exposed to a second annoyance consisting of a slightly negative evaluation from a fictitious partner, who was the target of aggression. The aggression measure required the participant to decide how long their partner (the target of aggression) should immerse their hand in ice-cold water. A 2 (cognitive load high/low) x 2 (inhibiting cues yes/no) ANOVA found main effects of both variables and their expected interaction. The results extend research that cognitive load increases displaced aggression and inhibiting cues decrease it. However, both main effects were qualified by the presence of the other moderator. Cognitive load only had a significant effect on TDA when inhibiting cues were also present. In turn, receiving inhibiting information only significantly reduced displaced aggression under low cognitive load. Therefore, the study demonstrated that under high cognitive load, inhibiting cues are prevented from decreasing TDA. The current research is discussed and interventions to reduce TDA are considered

The repeatability and reproducibility of four techniques for measuring horizontal heterophoria: Implications for clinical practice

PURPOSE: Convergence insufficiency, the most common binocular vision anomaly, is characterised by a receded near point of convergence and an exophoria which is at least 4 prism dioptres (Δ) larger at near than at distance. However, the repeatability of standard heterophoria measures are poorly understood. This study assessed the ability of four common heterophoria tests to detect differences of 4Δ by evaluating the inter- and intra-examiner variability of the selected techniques. METHODS: Distance and near horizontal heterophorias of 20 visually-normal adults were measured with the alternating prism cover test, von Graefe prism dissociation, Howell Card and Maddox Rod by two examiners at two separate visits using standardised instructions and techniques. We investigated inter- and intra-examiner variability using repeatability and reproducibility indices, as well as Bland-Altman analysis with acceptable limits of agreement defined as ±2Δ. RESULTS: The Howell card test had the lowest intra-examiner variability at both distance and near, as well as the best 95% limits of agreement (±1.6Δ for distance and ±3.7Δ for near). Inter-examiner reproducibility results were similar, although at near the alternating prism cover test had better repeatability (1.1Δ, 95% confidence intervals −1.1Δ to 4.0Δ) than the Howell card (1.4Δ, 95% confidence intervals −1.9Δ to 5.9Δ). CONCLUSION: The low repeatability of many standard clinical heterophoria tests limits the ability to reliably detect a 4Δ difference. The Howell Card provided the most repeatable and reproducible results indicating that this technique should be used to detect small changes in heterophoria magnitude and direction

Assessment of COVID-19 in primary care: the identification of symptoms, signs, characteristics, comorbidities and clinical signs in adults which may indicate a higher risk of progression to severe disease

No abstract available

Evidence Review: Assessment of COVID-19 in Primary Care: the Identification of Symptoms, Signs, Characteristics, Comorbidities and Clinical Signs in Adults which may Indicate a Higher Risk of Progression to Severe Disease

No abstract available

Evidence Review: Assessment of COVID-19 in Primary Care: The identification of symptoms, clinical signs, characteristics, and comorbidities in adults, children and young people, which may indicate a higher risk of progression to severe disease

No abstract available