On the completeness of certain classes of two stage sampling strategies

Summary In this paper the problem of estimation of the population mean, for a finite two statge population, under the assumptions of non-informativeness of labels of distinguishable units has been studied. Completeness of certain classes of strategies, for estimating the population mean, under a two stage random permutation model, has been established.     

Estimation of symmetric functions of a finite population

Summary Estimation of symmetric functions under the assumptions of noninformativeness of labels in a finite population of distinguishable units has been examined. The primitive strategies of srs, sample mean, sample variance etc. are found to play important roles.     

Vergleichende Analyse der technisch-wirtschaftlichen Bedingungen von PV-Anlagen Mit Süd- und Ost-West-Ausrichtung

PV power plants with east-west-orientation have a lower energy production per installed kW_p due to their orientation than those facing to south. Thus they need a reduction of costs to compensate the lack of energy production and to have the same cost effectiveness as PV plants with south-orientation. This paper tries to show, how and if PV plants with east-west-orientation can be more profitable than PV plants with south-orientation. Therefore, the energy production was simulated for PV plants with an orientation to east-west and to south with different inclinations in a place with high irradiation (Freiburg) and a place with low irradiation (Hamburg). A calculation of profitability was made for each PV plant including energy production as well as ascertained costs. This are the main outcomes:

The profitability of PV plants with east-west-orientation is not better than the profitability of PV plants with south-orientation.

The profitability of PV plants with east-west-orientation is better than the one of PV plants with south-orientation when the costs of mounting systems are much lower for east-west mounting-systems than for mounting-systems with south-orientation and the costs of grid-connection and rent are high too.

The profitability of PV plants with east-west-orientation is higher in regions with low irradiation.

     

On estimating nonnegative definite quadratic forms

It is often required to estimate a quadratic form in survey sampling, especially when one has to estimate the mean squared error of a linear estimator of the population total. In this note we consider the problem of obtaining uniformly nonnegative quadratic unbiased estimators for nonnegative definite quadratic forms. The estimators considered here are necessarily quadratic. Received January 1997     

Estimation under two stage random permutation models

Summary Estimation of the population mean under assumptions of non-informativeness of labels in a two stage finite population of distinguishable units has been studied. Under the random permutation model, for the two stage set up, sample mean, the natural estimator, is found to be the best.     

Stratification,midzuno-sen strategy and nonnegative unbiased variance estimation

When the ratio method is appropriate for estimating the population total one is faced with the problem of nonavailability of uniformly nonnegative unbiased variance estimators (nnuve). Here we highlight the twofold role of stratification in that it not only improves the efficiency of the ratio method of estimation but it also enhances the chances of getting uniformly nonnegative unbiased variance estimators.