Search Results

Normative issues associated with income inequality are discussed. A review of the debate over Paglin’s basic revision of the Gini coefficient is presented. The methodology for computing some alternative measures of income inequality is described.

This chapter covers the design, analysis, and interpretation of validity and reliability studies, particularly for exposure measures used in epidemiologic studies. It covers both intramethod (e.g., test-retest) reliability studies and intermethod reliability studies (e.g., in which a measurement method to be used in an epidemiological study is compared to a more accurate but not perfect method). Measures of reliability are primarily important for what they reveal about the validity of a measure, and this concept is emphasized for both design and interpretation of reliability studies. The choice of an analysis technique depends on whether the exposure is measured as a continuous variable or a categorical variable and whether the study is a validity or intermethod study vs. an intramethod study. For intramethod studies, versions of the intraclass correlation coefficient are used for continuous exposure variables and versions of kappa are used for categorical variables.

This chapter analyzes why a business or a project fails to meet its debt-service commitments. It is devoted to a full-scale credit risk analysis of a lending decision and pricing of a particular risk category of a borrower, using real-life examples. The approach is kept simple and practical, so that the system proposed can be easily implemented by lending organisations.

This chapter discusses the amplitude of population change in a variety of small rodent species, focusing on the latitudinal variations in population variability and population density. The coefficient of variation is used to measure population variability. The chapter begins by identifying the data needed to calculate the coefficient of variation. It then addresses whether population fluctuations are stronger at high latitudes and whether small rodent maximum densities are higher in more productive habitats or lower in predator-rich habitats.

This chapter reviews the most widely used metrics to analyze mutual fund performance. It covers tools, risk metrics, and rating criteria popular with both academics and practitioners. Measurement of relative fund performance is tested with a set of dimensionless ratios including the coefficient of variation, Sharpe ratio, and Treynor ratio. Interpreting the precise amount of relative under- or over-performance is difficult with dimensionless ratios. In response to this drawback of using such measures, several researchers developed mutual fund performance metrics that quantify risk-adjusted performance to a greater degree. For example, the M² measure, Jensen’s alpha, and the Carhart model are useful in quantifying risk-adjusted performance in percentage terms. The chapter presents recent extensions or enhancements to the Carhart model and also discusses the quantitative and qualitative risk metrics available from Morningstar.

Scale is now a central topic of research and theory in rangeland ecology, and non-equilibrium ideas have rapidly gained footing in the US and globally. But the problem of scale remains a daunting obstacle to effective rangeland management. Current scientific research indicates that areas with a high coefficient of variation of rainfall are dominated by non-equilibrium ecological dynamics. Highly variable precipitation still defies the temporal demands of capital accumulation, and climate change is projected to increase variability still further. The history of range science could have been different: scientists might have worked more closely with livestock producers to vary stocking rates, and rangelands might have been managed at larger scales, as in the case of the Mizpah-Pumpkin Creek Grazing District in southeastern Montana in the late 1920s. Community-based conservation groups have flourished throughout the West in recent decades, committed to collaborative approaches that permit greater flexibility and adaptive management at landscape scales. Science cannot be abstracted from its social contexts, and knowledge cannot be separated from the social processes that produce and condition it.

In finance, a common way of evaluating an investment uses the investment’s expected return and the investment’s risk, in the sense of the investment’s volatility, or exposure to chance. A version of this method derives from a general mean-risk evaluation of acts, under the assumption that only money, risk, and their sources matter. Although the method does not require a measure of risk, finance investigates measures of risks to assist evaluations of risks. An investment creates possible returns, and the variance of the probability distribution of their utilities is a measure of the investment’s risk. This measure neglects some factors affecting an investment’s risk, and so is satisfactory only in special cases. Another measure of risk is known as value-at-risk, or VAR. It also neglects some factors affecting an investment’s risk, and so should be restricted to special cases.

Among research publications in soil science, few have had a greater impact than those by Nielsen et al. (1973) or Biggar and Nielsen (1976). According to Science Citation Index, the former paper, entitled “Spatial variability of field-measured soilwater properties,” has been cited by scientific peers over 390 times. The 1976 paper, entitled “Spatial variability of the leaching characteristics of a field soil,” has been cited over 232 times. Experimental work presented in both papers represents the first-ever attempt at a large field-scale study of steady-state water and solute transport (Wagenet, 1986). Among the seminal findings of these two papers were as follows: (1) extensive spatial variability existed in soil hydraulic and solute transport properties within a relatively homogeneous field (important in the work of Pilgrim et al., 1982; Addiscott and Wagenet, 1985; Feddes et al., 1988; van dcr Molen and van Ommen, 1988); (2) soil water content, bulk density, and soil particle size exhibited normal frequency distributions, while distributions for hydraulic conductivity, hydraulic diffusivity, pore water velocity, and hydrodynamic dispersion were lognormal (work extended by van der Pol et al.. 1977; Rao et al., 1979); (3) frequency distributions were far superior to field-average parameter values (especially for lognormally distributed properties) in describing field transport behavior (demonstrated by Rao et al., 1979; Trangmar et al., 1985); (4) a simple unit hydraulic gradient method was shown to estimate saturated hydraulic conductivity accurately (results extended by Libardi et al., 1980; van Genuchten and Leij, 1992); (5) good correspondence was found between solute velocity and pore water velocity (key assumption in Jury and Fluhler, 1992); (6) and theoretical predictions of a linear relation between hydrodynamic dispersion and pore water velocity were shown to be obeyed at the field scale (result used widely by solute transport modelers, as discussed in Nielsen et al., 1986). The seminal works by Nielsen et al. (1973) and Biggar and Nielsen (1976) produced several new directions in soil science and vadose zone hydrology research. The most interesting was a series of papers that rejected the theoretical basis and practicality of using deterministic equations, and instead introduced stochastic approaches to describe field-scale water and solute fluxes.