BACKGROUND Accurate and reliable laboratory-based assays are needed for estimating HIV-1 incidence from cross-sectional samples. We recently described the development of a customized, HIV-1-specific Bio-Plex assay that allows for the measurement of HIV-specific antibody levels and avidity to multiple analytes for improved HIV-1 incidence estimates. METHODS To assess intra- and inter-laborator...

Point transect sampling of calling coveys has been advocated for estimating autumn abundance of northern bobwhite (Colinus virginianus; hereafter bobwhite). We conducted power analysis, over a range of expected bobwhite calling covey densities to determine levels of sampling required to obtain density estimates for calling coveys over a wide range of precision. We used distance/detection inform...

The technique introduced in this paper is a means for estimating and discovering underlying patterns for a large number of curves observed with heteroscedastic errors. Therefore, both the mean and the variance functions of each curve are assumed unknown and varying over time. The method consists of a series of steps. We transform using an orthonormal basis of functions in L2. In the transform d...

We derive a general formula for the noise variance in the flux of a source estimated from aperture photometry assuming (i) prior pixel-flux uncertainties are available for the image (e.g., computed a priori from a noise model), and (ii) noise is correlated amongst pixels. Correlated noise usually occurs in re-sampled and interpolated images (e.g., mosaics), with the degree of correlation depend...

Variances in the American Community Survey are estimated using a replicate weight methodology (Fay, 1995). In counties with small sample sizes, the variance estimates of poverty statistics show wide variation as a function of sample size. Generalized Variance Functions (GVF) can be used to smooth out the uncertainty of the design-based variance estimate. We propose incorporating GVFs with small...

• ABSTRACT We consider heteroscedastic linear models for which the variances are parametric functions of known regressors. Second order expansions are derived for a class of estimators which includes normal theory maximum likelihood and generalized least squares. The result is a fairly precise description of when conventional asymptotic variance formulae are optimistic; i.e., they underestimate...

The availability of intra-day data on the prices of speculative assets means that we can use quadratic variation like measures of activity in financial markets, called realised volatility, to study the stochastic properties of returns. Here we provide a statistical basis for realised volatility and show how it can be used to estimate the parameters of stochastic volatility models. Models covere...

In many engineering applications, we have to combine probabilistic, interval, and fuzzy uncertainty. For example, in environmental analysis, we observe a pollution level x(t) in a lake at different moments of time t, and we would like to estimate standard statistical characteristics such as mean, variance, autocorrelation, correlation with other measurements. In environmental measurements, we o...

Cytochrome P450 2D6 (CYP2D6), which has a large number of genetic polymorphisms, is involved in the metabolism of a wide range of substrates. Dextromethorphan (DM) is a well-known probe drug for CYP2D6 and metabolic ratio (MR) is often used to measure the enzyme activity in vivo. Using the literature values of DM MR, we estimated the inter-individual variability of CYP2D6 hepatic intrinsic clea...