In a recent article in the Water Resources Bulletin, Hansen and Narayanan (H-N) estimated several monthly time series models of municipal water demand for Salt Lake City, Utah. One model was then used to conduct an ex post analysis of water demand between 1975 and 1977 (Hansen and Narayanan, 1981. While H-N are to be commended for attempting to further knowledge in this area, several theoretical, econometric, and analysis problems exist in their study which we believe limits the usefulness of the material presented.
MODEL FORMULATIONSeveral problems exist in the model formulation section. Problems are encountered from either misspecification of equations, careless editing or presentation, or inadequate development of a theoretical model. For example, D1 a nongrowing season dummy, is reported to have a value of zero during the growing season and one during the nongrowing season; but in the matrix and equation presentations, the reverse appears to be the case. In H-N's twin nongrowing season equations, D1 was omitted from the nongrowing season equation. Yet in the matrix presentation, the coefficient of D1 a p pears as (8; -$). Although 8: has not been identified, we assume it is the intercept of the growing season equation since both quantity demanded and the error term are asterisked. If this is the case, this implies that D1 has a value of one during the growing season and zero during the nongrowing months. Although this error may appear minor, it is unclear to us if H-N truly understand the equation and matrix manipulation they are attempting to explain. In addition, individuals with little knowledge of econometrics would find this section difficult to understand.The process H-N appear to use to estimate the appropriate demand model implies that little attention is paid to theoretical development. They appear to have estimated two OLS equations (H-N, Figure 2), eliminated nonsignificant variables, reestimated, then experimented with different seasonal variables.Using this ad hoc framework with the same data would tend to yield a model with significant explanatory variables and a high R2 value; however, what they have is a model developed to fit the data rather than determining if economic theory explains water demand.
Little quantitative site‐specific infiltration, runoff and sediment transport data for Tahoe Basin soils under varying storm events or stage of development are available. Modular (Ml), F‐type (M2), Impact nozzle (M3), and Impact‐Fan nozzle (M4) rainfall simulators were evaluated as to their practicality and ability to characterize infiltration for the Cagwin Soil Series within the Tahoe Basin. Three slope (0–15,15–30, >30%) and four plot conditions (natural with duff [P1], natural without duff [P2], disturbed without duff [P3], and disturbed with duff [P4]) were studied. The measured data were incorporated into a modified Philip's infiltration model and multiple non‐linear regression analyses were used to examine relationships between method, slope, plot condition, and infiltration characteristics.t Simulation methods Ml and M4 produced statistically similar (P=0.01) infiltration data, as did M2 and M3 which produced lower infiltration rates. All were found suitable for use in Sierra Nevada watersheds. Ml was considered most practical. Slope had negligible effect on infiltration. The plot condition was found to significantly influence infiltration, and the effect of each plot condition was significantly different. Final infiltration rates ranged from 4.7 to 6.2 cm/hr. Thus, the Cagwin soil demonstrated moderate to high infiltration rates even when exposed to extreme storm conditions (8–10 cm/hr).
The feasibility and economic value of DNA paternity identification were investigated and illustrated using Nevada beef cattle operations. A panel of 15 microsatellites was genotyped in 2,196 animals from 8 ranches with a total of 31,571 genotypes. Probabilities of exclusion for each marker within ranch and across ranches were computed. Joint probabilities of exclusion for the 15 microsatellites were also determined, resulting in values over 0.99 for any individual ranch and across ranches. Dropping 1 or 2 microsatellites with the lowest probabilities of exclusion resulted in joint probabilities greater than 0.99 and with marginal reduction compared with the probabilities with 15 microsatellites. Formulas for benefit-cost analysis for a DNA paternity identification program in beef cattle were derived. Genotyping 15 microsatellites with 20 calves per sire resulted in benefits of $1.71 and $2.44 per dollar invested at bull culling rates of 0.20 and 0.30, respectively. The breakpoints for the program to be profitable occurred when the ratio of the price of 1 kg of calf liveweight over the cost of genotyping 1 microsatellite was greater than 1.1 for a bull culling rate of 0.30. Benefit-cost analysis was also derived under incomplete DNA paternity identification using a lower number of DNA markers than necessary to achieve joint probabilities of exclusion of 0.99. Approximately a 20% increase in the benefit-cost ratio was achieved using 10 vs. 12 microsatellites with incomplete paternity identification. The greater the number of bulls in the operation, the lower the benefit-cost ratio of the paternity testing program. Low probabilities of exclusion and a high number of bulls in the beef operation reduced the benefit-cost ratio dramatically. The DNA paternity identification programs are feasible and may be profitable for free-range beef cattle operations.
The efficiency of the water utility firms in rural Nevada and their input optimization are examined in this study. The empirical methodology incorporates a hedonic specification of the nonminimum globally concave cost function in estimating the effect of the regulatory environment and the quality of water services on the optimum utilization of inputs. Allocative distortions are introduced through shadow prices and are specified as functions of regressors which make distortion factors firm-and input-specific. The results show that 76 percent of the water utilities of rural Nevada in the sample overutilize energy relative to labor. The impact of allocative distortions on each firm's cost is also computed.
SUMMARYA rapid, simple method is described for estimating the area of rubber leaves from two measurements on the middle and one of the side leaflets. The relationship between the area of a leaflet (A) and its length × breadth (LB), described by the expression A = 0.654 LB, does not vary between the three leaflets or between leaves of different ages, and clonal differences are slight.
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