BACKGROUND Central venous catheters (CVCs) continue to be used at a high rate for dialysis access and are frequently complicated by thrombus-related malfunction. Prophylactic locking with an anticoagulant, such as heparin, has become standard practice despite its associated risks. Trisodium citrate (citrate) 4% is an alternative catheter locking… (More)
Between September 1979 and July 1981, 405 northern-English children, initially aged 11-12 years, each recorded all food and drink consumed on five occasions on each of three consecutive days. Sugars and nutrient intakes were calculated using food tables. The average total sugars intake was 118 g/d or 21% of the energy intake and 43% of the carbohydrate… (More)
The effect on the correlation coefficient of discretizing data was investigated in two ways. First, the theoretical effect of dichotomizing data was calculated, and it was shown that the resulting correlation coefficient is considerably less than that between the underlying bivariate normally distributed variables. Second, computer simulations were… (More)
In cell kinetic experiments, as in many other branches of biological science, we often sample at various stages of an experiment: we may for example take a sample of animals, then from each study a sample of sites, and from each site take replicate observations. This sampling process can be optimized to give maximum precision to an estimated quantity, but… (More)
The contribution of the fortification of flour with calcium carbonate to the Ca intake of 375, 11-14-year-old Northumbrian children has been calculated. Mean Ca intakes were above those currently recommended for children of this age. The fortification of flour supplied 16% of the total Ca intakes. Without the fortification, the percentage of these children… (More)
Post-operative pain is frequently measured by a visual analogue scale (VAS). The most common methods for analysing such data are the so-called time-by-time method and repeated measures analysis of variance. In the first, due to correlation between time points, successive tests are not independent and cannot measure the treatment effects over time. In the… (More)
In this article discussion is continued of the case where the response variable is continuous and the explanatory variable is discrete. Two particular situations are covered: the response variable survival time and the explanatory variable dichotomous: and the response variable continuous (but not survival time) and the explanatory variable discrete (but… (More)
Statistical methods such as regression analysis are often used to estimate cell kinetic parameters, such as cell birth rate or tumour growth rate. The standard errors which the statistical procedures provide may be considerable underestimates of the true uncertainty surrounding the parameter of interest.