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    Wyświetlanie 1-7 z 7
    Tytuł:
    Weryfikacja wielkopowierzchniowej metody okreslania miazszosci obiektu lesnego opartej na losowaniu warstwowym
    Autorzy:
    Bruchwald, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/811210.pdf
    Data publikacji:
    2000
    Wydawca:
    Polskie Towarzystwo Leśne
    Tematy:
    losowanie warstwowe
    dendrometria
    metoda wielkopowierzchniowa
    miazszosc drzewostanow
    lasy
    lesnictwo
    inwentaryzacja lasu
    Źródło:
    Sylwan; 2000, 144, 06; 5-14
    0039-7660
    Pojawia się w:
    Sylwan
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Zwiększenie efektywności inwentaryzacji lasu metodą losowania warstwowego
    Improving effectiveness of forest inventory by stratified sampling
    Autorzy:
    Banaś, J.
    Drozd, M.
    Zięba, S.
    Bujoczek, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/986979.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Leśne
    Tematy:
    lesnictwo
    inwentaryzacja lasu
    losowanie warstwowe
    poprawa efektywnosci
    sampling design
    inventory precision
    stratified sampling
    Opis:
    The purpose of the stratification is to group stands basing on the homogeneity of the measured feature. During periodic forest inventory in Poland, strata are created on the basis of age and the main species in stand within the boundary of forest district. In this work an improvement of distinguishing the strata during the forest inventory is presented. Three variants are considered: (1) distinguishing homogeneous strata in boundary of the whole forest district, not separately in forest subdistricts, (2) splitting species−aged strata into homogeneous substrata with respect to site quality, and (3) dividing strata of stands in the regeneration class with respect to stand density. Study was conducted in four mountain forest districts located in the Kłodzko Basin (SW Poland). Total area of these stands amounted to 43,052 ha, where 6,648 sample plots were established during the periodic inventory. ANOVA was used to test significance of the differences in tree volume and to assess variability reducing in distinguished substrata. Results indicated that in stands with age up to 70 years mean volume of trees on the sample plot does not differ significantly between sites, but in older stands difference was significant. Dividing age−species strata of stands older than 70 years into substrata according to site conditions influenced reduction of volume variability from 10 to 57% in newly created substrata. Dividing strata consisted of stands in regeneration class according to stand density index allowed to decrease the volume variability from 9 to 20%. Mean volume of trees in stands on similar sites does no differ significantly between subdistricts in the same forest district. Strata distinguished within the whole forest district are bigger and represented by more sample plots than on the subdistrict level, which significantly reduced standard error of volume and improved effectiveness of stratification in forest inventory.
    Źródło:
    Sylwan; 2017, 161, 10; 804-811
    0039-7660
    Pojawia się w:
    Sylwan
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analiza dokładności obrębowej metody inwentaryzacji lasu opartej na losowaniu warstwowym
    The accuracy of a novel forest inventory method based on stratified sampling
    Autorzy:
    Bruchwald, A.
    Wójcik, R.
    Zajączkowski, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1026758.pdf
    Data publikacji:
    2003
    Wydawca:
    Polskie Towarzystwo Leśne
    Tematy:
    losowanie warstwowe
    lesnictwo
    inwentaryzacja lasu
    urzadzanie lasu
    dokladnosc
    metoda obrebowa
    alder
    form factor
    empirical equation
    Opis:
    The paper provides an analysis of the accuracy of a novel forest inventory method for calculating stand volume based on stratified sampling. The analysis included stand age as an efficient element used in the construction of the strata, as well as assessment results of various methods of sample allocation. This novel inventory method was compared with the methods based on simple random sampling or systematic sampling. The theory of all analysed methods for calculating stand volume is based on the mathematical statistics called a „representative sampling method”.
    Źródło:
    Sylwan; 2003, 147, 05; 13-20
    0039-7660
    Pojawia się w:
    Sylwan
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Warstwowanie drzewostanów w statystycznej metodzie reprezentacyjnej pomiaru miąższości obrębu leśnego – praktyczna realizacja założeń
    Problems with strata determination in application of statistical method of growing stock assessment at forest division level
    Autorzy:
    Jabłoński, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/973245.pdf
    Data publikacji:
    2010
    Wydawca:
    Polskie Towarzystwo Leśne
    Tematy:
    lasy
    inwentaryzacja
    losowanie warstwowe
    warstwy gatunkowo-wiekowe
    dane inwentaryzacyjne
    leśnictwo
    obręby leśne
    miąższość drzewostanów
    stratified sampling
    auxiliary data
    Opis:
    New method of forest inventory based on stratified sampling was implemented in the State Forests National Forest Holding in Poland in 2003. Updated stands characteristics from previous inventory are used as auxiliary information to determine sample size and strata system, while results of the inventory are presented according to the new stands description. Paper presents analysis and assessment of the differences between updated and new data as well as their influence on sample size requirement and number of strata.
    Źródło:
    Sylwan; 2010, 154, 06; 397-404
    0039-7660
    Pojawia się w:
    Sylwan
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ocena dokładności obrębowej metody inwentaryzacji lasu opartej na losowaniu warstwowym
    Assessment of the accuracy of the forest district inventory method based on the stratified sampling
    Autorzy:
    Bruchwald, A.
    Miścicki, S.
    Dmyterko, E.
    Stereńczak, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/988954.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Leśne
    Tematy:
    lesnictwo
    miazszosc drzewostanow
    inwentaryzacja lasu
    metoda obrebowa
    losowanie warstwowe
    dokladnosc
    auxiliary variable
    dominant tree species
    sample allocation
    stratum
    Opis:
    The aim of the research was to assess the accuracy of the stratified sampling method used to estimate the standing volume of a forest district and to compare it with the accuracy of simple random sampling methods. The paper presents the variability of the variables affecting the accuracy of the stratified sampling method. We attempted to find the ways to increase this accuracy. The research was based on the empirical material collected on approximately 42,000 sample plots with a size of 50−500 m², and with an average of 737 plots per forest district. The standard deviation of the merchantable volume of trees on sample plots ranged from 87 to 213 m³/ha, with an average of 128 m³/ha. The coefficient of variation ranged from 5.3 to 28.5% (the average 40.8%). Using a simple random sampling method, the standard error of the volume ranged from 3.3 to 10.0 m³/ha (the average 4.8 m³/ha) and the relative error – from 1.01 to 3.41% (the average 1.55%). The absolute error of the stratified sampling method under which strata are formed on the basis of the main tree species and its age ranged from 2.9 to 7.4 m³/ha, the average 4.2 m³/ha, and the relative error ranged from 0.65 to 1.95%, 1.02% on average (tab.). The accuracy of the stratified sampling method was by 15% higher than that of the simple random sampling method. We found that the relationship between the volume of a sample plot and the main tree species and its age measured by the correlation coefficient was 0.453 on average. For the relationship between volume and age of stands this coefficient was on average 0.422, while between volume and main tree species – only 0.118. Stand age – as an auxiliary variable in formation of strata – proved to be of moderate usefulness resulting from a small difference in the standing volume of stands in older age classes. Main tree species turned out to be of slight usefulness in formation of strata, therefore it seems reasonable to find some other auxiliary variables to replace it.
    Źródło:
    Sylwan; 2017, 161, 11; 909-916
    0039-7660
    Pojawia się w:
    Sylwan
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Estimation of proportion
    Autorzy:
    Zieliński, Ryszard
    Powiązania:
    https://bibliotekanauki.pl/articles/748382.pdf
    Data publikacji:
    2008
    Wydawca:
    Polskie Towarzystwo Matematyczne
    Tematy:
    Frakcja, prawdopodobieństwo sukcesu w doświadczeniu Bernoulliego, estymator nieobciążony, estymator o jednostajnie minimalnym błędzie średniokwadratowym, estymator Bayesowski, losowanie warstwowe, randomizowane odpowiedzi, przedział ufności.
    Opis:
    W populacji składającej się z N elementów jest nieznana liczba M elementów wyróżnionych. W artykule w przystępny sposób prezentuję różne problemy związane z estymacją frakcji θ = M/N.
    A population of N elements contains an unknown number M of marked units. Problems of estimating the fraction θ = M/N are discussed. The well known standard solution isˆθ = K/n which is the uniformly minimum variance unbiased estimator, maximum likelihood estimator, estimator obtained by the method of moments, and in consequence it shares all advantages of such estimators. In the paper some versions of the estimator are considered which are more adequate in real situations. If we know in advance that the unknown fraction lies in a given interval (t1, t2) and we consider an estimator ˆθ1 as better than the estimator ˆθ2 if the average of its mean square error is smaller on that interval, then the optimal estimator is given by (3). The values of the estimator for (t1, t2) = (0, 0.5) and for (t1, t2) = (0.3, 0.4) in a sample of size n = 10 if the number of marked units in the sample equals K, are given in the table TABELKA and the mean square errors of these estimator, versus the error of the standard estimator ˆθ = K/n are presented in Rys. 2. Averaging the mean square error with a weight function, for example such as in Rys.3, gives us the Bayesian estimator with the mean square error like in Rys. 4 (for n = 10). If in some real situations we are interested in minimizing the mean square error “in the worst possible case”, the adequate is the minimax estimator. Another situation appears if the population can be divided in some more homogenous subpopulations, for example in two subpopulations with fractions of marked units close to zero or close to one in each of them. Then stratified sampling is more effective; then the mean square error of estimation may be significantly reduced. In the paper the problem of randomizedresponses is also presented, very shortly and elementarily. The problem arises if a unit in the sample can not be for sure recognized as “marked” or “not marked” and that can be done with some probability only. The situation is typical for survey interview: it allows respondents to respond to sensitive issues (such as criminal behavior or sexuality) while remaining confidential. The final section of the paper is devoted to some remarks concerning the confidence intervals for the fraction. The exact optimal solution is well known for mathematicians but it is probably not very easy for statistical practitioners to follow all theoretical details, and typically confidence interval based on asymptotic approximation of the binomial distribution by a normal distribution are used. That is neither sufficiently exact nor correct. The proper and exact solution is given by quantiles of a suitable Beta distribution which are easily computable in typical statistical and mathematical computer packages.
    Źródło:
    Mathematica Applicanda; 2008, 36, 50/09
    1730-2668
    2299-4009
    Pojawia się w:
    Mathematica Applicanda
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-7 z 7

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