Between Dec 19, 2024 and Jan 2, 2025, datasets can be submitted to DRUM but will not be processed until after the break. Staff will not be available to answer email during this period, and will not be able to provide DOIs until after Jan 2. If you are in need of a DOI during this period, consider Dryad or OpenICPSR. Submission responses to the UDC may also be delayed during this time.

Browsing by Subject "path analysis"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Fundamental tradeoffs generating the worldwide leaf economics spectrum
    (Ecological Society of America, 2006) Shipley, Bill; Lechowicz, Martin J; Wright, Ian; Reich, Peter B
    Recent work has identified a worldwide “economic” spectrum of correlated leaf traits that affects global patterns of nutrient cycling and primary productivity and that is used to calibrate vegetation–climate models. The correlation patterns are displayed by species from the arctic to the tropics and are largely independent of growth form or phylogeny. This generality suggests that unidentified fundamental constraints control the return of photosynthates on investments of nutrients and dry mass in leaves. Using novel graph theoretic methods and structural equation modeling, we show that the relationships among these variables can best be explained by assuming (1) a necessary trade-off between allocation to structural tissues versus liquid phase processes and (2) an evolutionary trade-off between leaf photosynthetic rates, construction costs, and leaf longevity.
  • Thumbnail Image
    Item
    Web Mining: Information and Pattern Discovery on the World Wide Web
    (1997) Cooley, Robert; Mobasher, Bamshad; Srivastava, Jaideep
    Two important and active areas of current research are data mining and the World Wide Web. A natural combination of the two areas, sometimes referred to as Web mining, has been the focus of several recent research projects and papers. As with any emerging research area there is no established vocabulary, leading to confusion when comparing research efforts. Different terms for the same concept or different definitions being attached to the same word are commonplace. The term Web mining has been used in two distinct ways. The first, which is referred to as Web content mining in this paper, describes the process of information or resource discovery from millions of sources across the World Wide Web. The second, which we call Web usage mining, is the process of mining Web access logs or other user information user browsing and access patterns on one or more Web localities. In this paper we define Web mining and, in particular, present an overview of the various research issues, techniques, and development efforts in Web content mining and Web usage mining. We focus mainly on the problems and proposed techniques associated with Web usage mining as an emerging research area. We also present a general architecture for Web usage mining and briefly describe the WEBMINER, a system based on the proposed architecture. We conclude this paper by listing issues that need the attention of the research community.