نتایج جستجو برای: stratified random sampling
تعداد نتایج: 494458 فیلتر نتایج به سال:
Prescribed fire was introduced to high density ponderosa pine stands at Fort Valley and Long Valley Experimental Forests in 1976. This paper reports on mineral soil total carbon (C) and nitrogen (N) at Long Valley. Total soil C and N levels were highly variable and exhibited an increasing, but inconsistent, concentration trend related to burn interval. Total N ranged from 0.1 to 0.45%. Randomly...
Sampling errors are generally believed to dominate the errors of analytical measurement during the entire environmental data acquisition process. Unfortunately, environmental sampling errors are hardly quantified and documented even though analytical errors are frequently yet improperly reported to the third decimal point in environmental analysis. There is a significant discrepancy in directly...
Monitoring programs for urban runoff have not been assessed for effectiveness or efficiency in estimating mass emissions. In order to determine appropriate designs for stormwater, total suspended solids (TSS) and flow information from the Santa Ana River was collected nearly every 15 min for every storm of the 1998 water year. All samples were used to calculate the "true load" and then three wi...
We extend the random permutation model to obtain the best linear unbiased estimator of a finite population mean accounting for auxiliary variables under simple random sampling without replacement (SRS) or stratified SRS. The proposed method provides a systematic design-based justification for well-known results involving common estimators derived under minimal assumptions that do not require sp...
Tourism in general has become one of the major cultural and economic forces in the world today and is regarded as an important means to benefit local communities. Langkawi for example, has experienced tremendous development since declared a duty free island in 1987. Many construction projects are carried out on the islands with only one purpose: to accommodate tourism development. Rapid investm...
This paper’s centre of attention is on the problem of data mining (in general) and clustering (in specific) on a hidden web data. We know that data mining is a process that analyzes and extracts knowledge from large amounts of data which provides useful information to users. Hidden or deep web data is the database located at remote system .So, to access such data, we need query interface or HTM...
A nearly complete and undisturbed Miocene carbonate sequence is present in the easternmost part of the UmbriaMarche basin, Italy, which is ideal for detailed and integrated stratigraphic investigations of the Miocene Epoch. In this study, we were trying to obtain evidence for the presence or absence of distal ejecta from the 15 Ma Ries impact structure in southern Germany, located about 600 km ...
In this paper we show that, for each Ekedahl-Oort stratum contained in the supersingular locus, the number of its irreducible components is equal to a class number of a quaternion unitary group. MSC: primary: 14K10; secondary: 11G10; 14L05
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