We describe a new indicator dilution method of measuring cardiac output in man. A bolus injection of lithium chloride 0.6 mmol was given via a central venous catheter and arterial plasma [Li+] recorded using a specially developed sensor incorporating an Li(+)-selective electrode. Cardiac output was derived from the lithium dilution curve, with a correction for packed cell volume. Lithium diluti...

Clinical pathology testing of rodents is often challenging due to insufficient sample volume. One solution in clinical veterinary and exploratory research environments is dilution of samples prior to analysis. However, published information on the impact of preanalytical sample dilution on rodent biochemical data is incomplete. The objective of this study was to evaluate the effects of preanaly...

An instance-based model of the effects of age of acquisition (AoA) is offered and derived predictions are considered. A face-categorisation experiment is reported which tested these predictions. Nine participants made speeded-categorisation judgements of 185 faces from two TV shows. Ratings were given for the faces’ frequency of occurrence in the shows and, for each face, the length of time the...

Regression adjustments are often made to experimental data. Since randomization does not justify the models, almost anything can happen. Here, we evaluate results using Neyman’s non-parametric model, where each subject has two potential responses, one if treated and the other if untreated. Only one of the two responses is observed. Regression estimates are generally biased, but the bias is smal...

As statistical classifiers become integrated into real-world applications, it is important to consider not only their accuracy but also their robustness to changes in the data distribution. In this paper, we consider the case where there is an unobserved confounding variable z that influences both the features x and the class variable y. When the influence of z changes from training to testing ...

In this paper we examine theoretically and by simulation whether or not unobserved heterogeneity independent of the included regressors is really an issue in logit, probit and loglog models with both binary and fractional data. We found that unobserved heterogeneity: (i) produces an attenuation bias in the estimation of regression coefficients; (ii) is innocuous for logit estimation of average ...

Antimicrobial resistance is a phenomenon of increasing importance, as demonstrated by the emergence of different international antimicrobial resistance surveillance programs. The aim of this research was to perform an antimicrobial resistance evaluation in indicator bacteria isolated from pigs and poultry in Chile. One hundred E s c h e r i c h i a c o l i and 80 E n t e r o c o c c u s species...

BACKGROUND The attenuation of the relationship between disease and a risk factor subject to error through 'regression dilution' is well recognized, and researchers often make attempts to adjust for its effects. However, the adjustment methods most often adopted in cohort studies make an implicit assumption that the relationship is driven exclusively by current error-free levels of the risk fact...

AIMS To estimate the potential effectiveness of different "high-risk" and "population" approaches to the primary prevention of cardiovascular disease (CVD) in middle-aged British men, after correction for regression dilution bias. METHODS AND RESULTS We used a combination of cohort and randomised controlled trial evidence to estimate the effectiveness of high-risk strategies, based on the ide...

Local polynomial regression is a convenient method for smoothing scatterplots with readily available software. However, it well known that variable amounts of bias are induced by the operation. This article proposes simple visualization tool based on approximate confidence intervals which can alert data analyst to regions function domain might be susceptible unacceptably large levels bias, and ...