Articles containing the keyword 'statistical methods'
Category : Article
Much of forestry data is characterized by a longitudinal or repeated measures structure where multiple observations taken on some units of interest are correlated. Such dependencies are often ignored in favour of an apparently simpler analysis at the cost of invalid inferences. The last decade has brought to light many new statistical techniques that enable one to successfully deal with dependent observations. Although apparently distinct at first, the theory of Estimating Functions provides a natural extension of classical estimation that encompasses many of these new approaches. This contribution introduces Estimating Function Theory as a principle with potential for unification and presents examples covering a variety of modelling issues to demonstrate its applicability.
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Schabenberger,
E-mail:
os@mm.unknown
- Gregoire, E-mail: tg@mm.unknown
A simulation approach was applied to study the pattern of environmental variability and the relative statistical efficiency of 14 different plot types. The study material consisted of two nine-year-old field tests of Scots pine (Pinus sylvestris L.). The area of the test sites was 1.57 and 0.67 hectares. The efficiency was measured as the error variance attached to the estimate of family mean and the total size of a test needed to detect a given, least significant difference between two family means. The statistical efficiency tended to decline along with increasing plot size. The importance of plot shape was negligible compared to plot size. The highest efficiency was obtained with single-tree plots. Non-contiguous plots appeared to be considerably more efficient than block plots of equal size. The effects of intergenotypic competition on the choice of plot type are discussed.
The PDF includes an abstract in Finnish
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Haapanen,
E-mail:
mh@mm.unknown
At a joint meeting of the Finnish Statistical Society and the Society of Forestry in Finland on 17.10.1984, papers were presented on the history and mathematical foundations of statistical methods used in forest inventory in Finland. The advantages and applicability of Bayresian methods and methods of spatial statistics were also discussed. In two papers, forest inventories were examined as part of a forest information system and the information demands of the user were discussed.
This article includes eight presentation held in the meeting. The papers have each a summary in English.
Among the users of factor analysis there seems to be a tendency to extend the use of this method to tasks where it suits poorly. It is therefore important to emphasise at least the following aspects: 1) More critical attention should be paid to problems of interpretation especially at situations where method is aimed at analysing the causal relationships among the variables; 2) The study problem should be stated so clearly as to make it plausible to evaluate the suitability of factor model to the problem.
The PDF includes a summary in English.
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Järveläinen,
E-mail:
vj@mm.unknown
A hypothetic problem is outlined as an example of the type of problem to which factor analysis should not be applied. Apart from this, attention is paid to industrialisation, a concept characterised by several variables, none of which can be held constant while analysing its influence on attitudes by multi-variable cross-tabulation techniques.
The PDF includes a summary in English.
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Riihinen,
E-mail:
pr@mm.unknown
Some alternative ways of using factor analysis in the field of forest owners’ behaviour are explored in the article, in the light of two new Finnish publications. The philosophical and mathematical propertied of factor analysis are often considered too restrictive, and thus its applicability to different fields too limited. A good knowledge of the method and the subject matter theories seems to be an important prerequisite for a successful application of factor analysis. Otherwise the researcher is too dependent on the general recommendations concerning the use of factor analysis and cannot fit its use in his special situation and the whole methodological setting of the study.
The PDF includes a summary in English.
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Hahtola,
E-mail:
kh@mm.unknown
The article is a lectio praecursoria held on May 18, 1968 at the University of Helsinki. It deals with some aspects connected with the adaptation of mathematic-statistical methods and in particular with multivariate methods. Among these regression, factor, and principal-component analysis are mostly used by the Finnish forest economists.
The PDF includes a summary in English.
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Mäkelä,
E-mail:
jm@mm.unknown
