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Wyszukujesz frazę "cluster sampling" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Variance estimation in stratified adaptive cluster sampling
Autorzy:
Yasmeen, Uzma
Noor-ul-Amin, Muhammad
Hanif, Muhammad
Powiązania:
https://bibliotekanauki.pl/articles/2034098.pdf
Data publikacji:
2022
Wydawca:
Główny Urząd Statystyczny
Tematy:
variance estimator
stratified sampling
stratified adaptive cluster sampling (SACS)
Opis:
In many sampling surveys, the use of auxiliary information at either the design or estimation stage, or at both these stages is usual practice. Auxiliary information is commonly used to obtain improved designs and to achieve a high level of precision in the estimation of population density. Adaptive cluster sampling (ACS) was proposed to observe rare units with the purpose of obtaining highly precise estimations of rare and specially clustered populations in terms of least variances of the estimators. This sampling design proved to be more precise than its more conventional counterparts, including simple random sampling (SRS), stratified sampling, etc. In this paper, a generalised estimator is anticipated for a finite population variance with the use of information of an auxiliary variable under stratified adaptive cluster sampling (SACS). The bias and mean square error expressions of the recommended estimators are derived up to the first degree of approximation. A simulation study showed that the proposed estimators have the least estimated mean square error under the SACS technique in comparison to variance estimators in stratified sampling.
Źródło:
Statistics in Transition new series; 2022, 23, 1; 173-184
1234-7655
Pojawia się w:
Statistics in Transition new series
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Two-stage cluster sampling with unequal probability sampling in the first stage and ranked set sampling in the second stage
Autorzy:
Ugwu, Michael C.
Madukaife, Mbanefo S.
Powiązania:
https://bibliotekanauki.pl/articles/2108165.pdf
Data publikacji:
2022-09-14
Wydawca:
Główny Urząd Statystyczny
Tematy:
cluster sampling
population mean estimator
probability proportional to size sampling
ranked set sampling
relative efficiency
Opis:
In this research work we introduce a new sampling design, namely a two-stage cluster sampling, where probability proportional to size with replacement is used in the first stage unit and ranked set sampling in the second in order to address the issue of marked variability in the sizes of population units concerned with first stage sampling. We obtained an unbiased estimator of the population mean and total, as well as the variance of the mean estimator. We calculated the relative efficiency of the new sampling design to the two-stage cluster sampling with simple random sampling in the first stage and ranked set sampling in the second stage. The results demonstrated that the new sampling design is more efficient than the competing design when a significant variation is observed in the first stage units.
Źródło:
Statistics in Transition new series; 2022, 23, 3; 199-214
1234-7655
Pojawia się w:
Statistics in Transition new series
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wielkoobszarowa inwentaryzacja stanu lasu źródłem informacji o powierzchni lasów w Polsce
Forest area in Poland based on national forest inventory
Autorzy:
Jabłoński, M.
Mionskowski, M.
Budniak, P.
Powiązania:
https://bibliotekanauki.pl/articles/985910.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
Polska
lasy
lesistosc
powierzchnia lasow
zrodla informacji
inwentaryzacja lasu
inwentaryzacja wielkopowierzchniowa
forest definition
land use
land cover
nfi
cluster sampling
Opis:
Forest area in Poland is annually evaluated as a part of public statistics research. However, this information is based on land use resulting from Land and Property Register (LPR). Delays in the reclassification of afforested land, as well as the natural expansion of trees on abandoned agricultural lands, observed over the last decades, caused that information from LPR becomes unreliable. In many countries forest area is assessed within the National Forest Inventories (NFIs) based upon systematic grid of sample plots. NFI in Poland has been performed since 2005, in 4×4 kilometre grid with clusters consisting of five plots. Until 2014 measurements were made only on these sample plots which were located in forest according to LPR records. Within the 3rd NFI cycle (2015−2019) the areas fulfilling the criteria of forest definition, but located on non−forest land referring to LPR, has become the object of study. The aim of this work is to present statistical approach for evaluation of forest area using NFI cluster sampling data. Additionally, results from two year measurements (2015−2016) were analysed and compared with LPR data. Attributes of NFI plots allow to apply national forest criteria as well as the land use and land cover thresholds recommended by Food and Agriculture Organization of the United Nations or Kyoto Protocol. Our research shows that forest cover in Poland is in the range of 32.8−33.0%, depending on forest definition used, and is almost 3% higher than official LPR data (30.1%). The standard error of forest cover, based on two years NFI data is 0.44. Thus, with 95% probability the true value of this parameter lies between 31.9 and 33.7%, while country thresholds of forest definition are used. Additionally it was assessed that using the entire NFI cycle data the standard error of forest cover should be lower i.e. less than 0.3. The National Forest Inventory seems to be an appropriate tool for monitoring forest area in Poland.
Źródło:
Sylwan; 2018, 162, 05; 365-372
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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