Estimation employing a priori information within mass appraisal and hedonic pricing models

Both statistical appraisal and hedonic pricing models decompose houses into a set of individual characteristics. Regression estimates yield the contribution of each characteristic to total value. Unfortunately, straightforward application of OLS may produce untenable results such as implausible coefficient magnitudes or incorrect signs. Often the suspected cause is multicollinearity. This article examines the effect on estimation efficiency of differing levels of multicollinearity, R², and a priori information in the form of sub-market cost data, by comparing inequality restricted least squares (IRLS) with OLS in a series of Monte Carlo experiments. The IRLS procedure investigated here hybridizes the statistical market approach implemented by OLS, and the more traditional cost approach. The experiments show dramatic gains in estimation efficiency from exploiting a priori information through IRLS.     

Realising the Potential – and Lost Opportunities – for Peer Collaboration in D&T Setting

This paper follows up our theoretical discussion of the potential for collaborative problem solving in Design and Technology (Hennessy and Murphy, 1999). In this paper we report our empirical investigation of peer collaboration in a setting where we identified the presence of significant pre-conditions for productive collaboration. The study investigated the participation of two boys aged 13 who worked together with their teacher over 8 weeks in designing and making an aid for a child with a disability. We analysed their participation using a framework of key features derived from the research literature. Our analyses yielded evidence of effective collaboration in the early design stage, but the students' collaboration and their progress were subsequently undermined. The reasons related to the students' ability to collaborate and the tension for the teacher between students' learning needs and client needs within an authentic activity. The outcome was a successful product but a wealth of lost opportunities – and lack of support – for the students' collaborative problem solving and Design and Technology (D&T) learning. Our observations confirm that despite little evidence of collaboration in D&T, this setting offers extensive resources for supporting collaboration in joint design, planning and problem-solving activities. We also identify impediments to collaboration as a learning mechanism. This revised version was published online in July 2006 with corrections to the Cover Date.     

Faster Implied Volatilities via the Implicit Function Theorem

We present a faster, more accurate technique for estimating implied volatility using the standard partial derivatives of the Black‐Scholes option‐pricing formula. Beside Newton‐Raphson and slower approximation methods, this technique is the first to provide an error tolerance, which is essential for practical application. All existing noniterative approximation methods do not provide error tolerances and have the potential for large errors.     

The quartiles of the maximum entropy distribution

The quartile points and interquartile range of the maximum entropy (ME) distribution and sample distribution are compared, using expected values for sampling from a standard normal population. For sample sizes n?20 such that the sample quartile points are uniquely defined, the ME quartile points and interquartile range are found to have lower mean-squared error (MSE).     

Using FTE and RVU performance measures to assess financial viability of academic nurse-managed centers

Financial performance measures are essential to improve the fiscal management of academic nurse-managed centers (ANMCs). Measures are compared among six ANMCs in a consortium and against an external, self-sustainable, profitable ANMC and national data for family practice physicians. Performance measures help identify a center's strengths and weaknesses facilitating the development of strategies aimed at a variety of targets (business practices related to revenue and costs) to improve financial viability. Using a variety of financial performance measures to inform decision making will aid ANMCs in keeping their doors open for business.