Quantity quantiles linear regression

We show that the definition of the θth sample quantile as the solution to a minimization problem introduced by Koenker and Bassett (Econometrica 46(1):33–50, 1978) can be easily extended to obtain an analogous definition for the θth sample quantity quantile widely investigated and applied in the Italian literature. The key point is the use of the first-moment distribution of the variable instead of its distribution function. By means of this definition we introduce a linear regression model for quantity quantiles and analyze some properties of the residuals. In Sect. 4 we show a brief application of the methodology proposed. This research was partially supported by Fondo d’Ateneo per la Ricerca anno 2005—Università degli Studi di Milano-Bicocca. The paper is the result of the common work of the authors; in particular M. Zenga has written Sects. 1 and 5 while P. Radaelli has written the remaining sections.     

Detecting bliss synergy in in vivo combination studies with a tumor kinetic model

Linear models are generally reliable methods for analyzing tumor growth in vivo, with drug effectiveness being represented by the steepness of the regression slope. With immunotherapy, however, not all tumor growth follows a linear pattern, even after log transformation. Tumor kinetics models are mechanistic models that describe tumor proliferation and tumor killing macroscopically, through a set of differential equations. In drug combination studies, although an additional drug‐drug interaction term can be added to such models, however, the drug interactions suggested by tumor kinetics models cannot be translated directly into synergistic effects. We have developed a novel statistical approach that simultaneously models tumor growth in control, monotherapy, and combination therapy groups. This approach makes it possible to test for synergistic effects directly and to compare such effects among different studies.     

Why Rates of Growth of Employment Differ: A Quantitative Approach to an International Comparison

ABSTRACT: This essay aims at presenting a quantitative assessment of the incidence of structural differences in output and employment composition, and of differential dynamics of the sectoral production and productivity, in order to explain the divergences in net employment growth in advanced market economies. The point of reference is the extremely divergent record, in terms of employment creation, of the United States on one hand, and Western European countries on the other. In the period 1973-80, for example, although the average growth rates of GNP were, on a cyclical average, similar in the U. S. A. and the EEC areas as a whole, additional job openings were about 14 million in the USA against less than half a million in the EEC. A structural, medium-run differential in the aggregate Employment/GNP elasticity appears to have characterized the performances of these economic systems. The 'source’of this differential are analyzed, utilizing a model of sectoral decomposition of employment and output trends. Simulation exercises are carried out, in order to assess the specific role of productivity, sectoral demand composition and sectoral employment composition, in determining the overall elasticity result. The comparative analysis takes into consideration the differential factors for the USA and Japan, together with the four major Western European countries (German Fed. Rep., France, Italy, and the United Kingdom).     

A Subjective Spin on Roulette Wheels

We provide a simple behavioral definition of ‘subjective mixture’ of acts for a large class of (not necessarily expected‐utility) preferences. Subjective mixtures enjoy the same algebraic properties as the ‘objective mixtures’ used to great advantage in the decision setting introduced by Anscombe and Aumann (1963). This makes it possible to formulate mixture‐space axioms in a fully subjective setting. For illustration, we present simple subjective axiomatizations of some models of choice under uncertainty, including Bewley's model of choice with incomplete preferences (2002).