A controversial technique for testing the hypothesis that physicians induce demand involves two stage least squares (TSLS) regression analysis of cross-section data on physician supply and utilization. This paper tests the power of TSLS by applying it where there is at most only a trivial amount of demand inducement--the demand for childbirths. We find 'evidence' of inducement of childbirths, c...

The veridical perception of collinearity between two separated lines is distorted by two parallel lines in the space between them (the Poggendorff illusion). This paper tests the conjecture that the perception of collinearity of separated lines is based on a two-stage mechanism. The first stage encodes the orientation of the virtual line between the proximal terminators of the target lines. The...

Genome-wide association (GWA) studies require genotyping hundreds of thousands of markers on thousands of subjects, and are expensive at current genotyping costs. To conserve resources, many GWA studies are adopting a staged design in which a proportion of the available samples are genotyped on all markers in stage 1, and a proportion of these markers are genotyped on the remaining samples in s...

Previous research has shown that damage to the neural substrates of orthographic processing can lead to functional reorganization during reading (Tsapkini et al., 2011); in this research we ask if the same is true for spelling. To examine the functional reorganization of spelling networks we present a novel three-stage Individual Peak Probability Comparison (IPPC) analysis approach for comparin...

Concept mapping is a tool to assist in strategic planning that allows planners to work through a sequence of phases to produce a conceptual framework. Although several studies describe how concept mapping is applied to various public health problems, the flexibility of the methods used in each phase of the process is often overlooked. If practitioners were more aware of the flexibility, more pu...

A study on the general population from both cadmium-polluted and control areas and on cadmium alloy workers indicates that beta 2-MG in urine is very closely correlated with aging, but it indicates an association with cadmium exposure. However, the age factor is stronger than cadmium exposre in both polluted and control areas among persons without clinical proteinuria. On the other hand, cadmiu...

A two-stage case-control design, in which exposure and outcome are determined for a large sample but covariates are measured on only a subsample, may be much less expensive than a one-stage design of comparable power. However, the methods available to plan the sizes of the stage 1 and stage 2 samples, or to project the precision/power provided by a given configuration, are limited to the case o...

We investigated how the primate visual system solves the difficult problem of representing multiple motion vectors in the same part of the visual space--the problem of motion transparency. In the preceding companion article we reported that displays with locally well-balanced motion signals in opposite directions are perceptually nontransparent (i.e., one does not see two coherent moving surfac...

We compare experimentally two contest designs. In the between-group design (BGD), cohorts compete with one another in stage 1 and a single cohort is then advance to stage 2. In stage 2, members of this cohort compete for a single prize. In the withingroup design (WGD), the order of the competition is reversed. Our findings support the theoretical conclusion that the WGD is superior to BGD in ge...

Statisticians typically estimate the parameters of latent class and latent profile models using the Expectation-Maximization algorithm. This paper proposes an alternative two-stage approach to model fitting. The first stage uses the modified k-means and hierarchical clustering algorithms to identify the latent classes that best satisfy the conditional independence assumption underlying the late...