A Varying Parameters Approach to Constructing House Price Indexes

Conventional housing price index models assume interperiodparameter stability and typically employ either repeat sales or hedonic methodologies. This paper introduces a method of index construction that combines multiple sales observations with single sale transactions while permitting characteristics prices from hedonic regressions to vary over time. A test for interperiod parameter stability is provided. Each period's data are arranged by location and repeat sales are matched by rows. This construction allows greater use of sample information and acknowledges the unique contribution of repeat sales to the estimation process. It also produces intertemporal error correlations that can be beneficially exploited by the seemingly unrelated regressions (SUH) technique. The paper also demonstrates a significance test for error correlation and discusses the treatment of unequal numbers of observations among index periods.     

Strategic groups as reference groups: Theory,modeling and empirical examination of industry and competitive strategy

Previous studies on strategic groups have mainly focused on their static characteristics in order to test the theory of strategic groups and intraindustry performance differences (Porter, 1979; Cool and Schendel, 1988; Fiegenbaum and Thomas, 1990). In contrast, this study takes a longitudinal, dynamic perspective and describes the forces driving strategic group membership and structural evolution. It proposes that a strategic group acts as a reference point for group members in formulating competitive strategy. A partial adjustment model of strategic mobility is then developed which incorporates the idea of a strategic group as a reference group. It models strategic change in an industry both within and across strategic groups. The model is tested in the context of an in-depth industry analysis of the more significant firms in the insurance industry over the 1970-84 time period. The results suggest that strategic groups act as reference points for firm strategies and that predictions of future firm strategies and industry/group structures may also be successfully derived.     

Employment,schooling and productivity growth

Summary This paper presents an empirical analysis of labour demand and labour productivity growth in The Netherlands. Assuming an aggregate production function with as factors capital and 3 types of labour, distinguished by educational attainment, cost minimization leads to a set of 3 labour demand relations to be estimated on time series data. Using the estimates and the implied elasticities, aggregate labour productivity growth is decomposed into factor substitution, autonomous factors, labour time shortening, economies of scale, utilization rates and the increased educational level of the working population. The contributions of substitution, utilization rates and education appear to be substantial, notably in the seventies.

List of symbols

Variables a _i Efficiency index of skill leveli - C production - h _i working-time index for skill leveli - g _i steady-state growth rate of skill leveli - K capital stock - L _i employment volume of skill leveli - L _i ^* desired level of labour skill leveli - p output price - p ^* desired output price - s _i ^* long-run static labour shares in the production value - p _k rental price of capital - P index of total factor productivity - P _l index of labour productivity - u _i utilization rate of skill leveli - u _k utilization rate of capital - w _i wage rate for skill leveli - y production volume - y _yij Hicks partial elasticities of complementarity - _i steady-state cost share of skill leveli - _k Bk steady-state cost share of capital - _f lf highest level price index in cost function nesting - _g 4 intermediate level price index in cost function nesting - _h 4 lowest level price index in cost function nesting - _i steady-state relative wage share of skill leveli - _ij Allen partial elasticities of substitution Parameters d _i l adjustment speed of skill leveli - d _p price adjustment speed - M mark-up on marginal costs - scale elasticity of production - _i distribution parameter in cost function,i = 3, g - _i distribution parameter in cost function,i = k, h - _i distribution parameter in cost function,i =1, 2 - _i autonomous labour productivity growth for skill leveli - _i cost share of skill level in base year - _f production cost index in base year - _i hours elasticity in labour efficiency index - group elasticity of substitution betweenL ₃ and (K, (L ₁,L ₂)) - _g Og group elasticity of substitution betweenK and (L ₁,L ₂) - _h 6h group elasticity of substitution betweenL ₁ andL ₂ We would like to thank B. Downey, G.M.M. Gelauff, A. Nieuwenhuis, J.M.M. Ritzen, J.C. Siebrand and an unknown referee for helpful comments on earlier drafts.     

Maximizing purchase decision factors other than price

Assessing and acquiring technology does not have to be chaotic, driven solely by price, clinical preference, and emotion. With the tools available, it can be distilled to a process of organized common sense, which results in maximum flexibility for the user and allows materiel managers to procure the best, most cost-effective equipment for the hospital.     

Body support testing and rating

The REF, C, and score are a means to give quantitative values for product performance. Other product variables defined as humidity control factor, shear control factor, differential temperature control factor, product life factor, and cost factor were not addressed as part of this study. Additional variables include delivery, maintenance, and warranties. These components can be added to the score in some weighted manner as they become clinically founded. Interface pressures and shears were not measured for beds that are gatched. Each product tested will have characteristics pertinent to its own design that must be addressed to minimize sacral and coccyx skin breakdown when subjects are in this posture because some pneumatic pads bottom out to give excessive sacral and coccyx pressure while others wrinkle when used in this position. This is of major concern when one considers that the coccyx is more susceptible to pressure than any other bony prominence. There may be some aversion to labeling support product performance because it will allow the purchaser to know what is being bought. This initial study indicates the feasibility of quantitating what all patients require: a valid interface support surface for each specific need. The user can be adequately informed before the purchase as to a product's merits without being influenced by the results of inadequate testing, referrals, or sales media influences. Although cushions, shoes, or other prosthetic/orthotic devices were not part of this study, it is appropriate to rate all these devices in a similar manner by simply comparing pressure relief attained to that desired, expressing the result as a percentage of the worst case, and then labeling the product accordingly. Those subjects with sensation can rate comfort as part of the overall score. For cushions, ischial tuberosity pressure relief can be expressed as a percentage of the maximum attainable relief. Metatarsal head relief during gait as well as during static testing can be measured, and claims can be made for shoes and sneakers. Where impact loads and shear forces are paramount, the score must comprise appropriate parameters. Similarly, amputee distal stump relief as a percentage of worst case could be specified by the fitter. Iliac crest relief as a percentage of worst case can also be specified by the fitter. In all instances the score is not a subjective rating but one that can be measured correctly. All body support products can be given an REF, C value, and score as well as other qualifying values where appropriate instrumentation and sufficient subject sampling is used.     

U.S. Savings Bonds: the planned-gift forgotten asset

As older Americans take a close look at their assets, promote their interest in unlocking the wealth accumulation in their U.S. Saving Bond holdings. Use careful planning and advice when promoting this gift strategy.