vegan-refs.bib

@ARTICLE{Blanchet2008,
  title       = "Forward selection of explanatory variables",
  author      = "Blanchet, F Guillaume and Legendre, Pierre and Borcard, Daniel",
  affiliation = "D\'{e}partment de Sciences Biologiques, Universit\'{e} de
                 Montr\'{e}al, C.P. 6128, Succursale Centre-ville,
                 Montr\'{e}al, Qu\'{e}bec H3C 3J7, Canada. gblanche@ualberta.ca",
  abstract    = "This paper proposes a new way of using forward selection of
                 explanatory variables in regression or canonical redundancy
                 analysis. The classical forward selection method presents two
                 problems: a highly inflated Type I error and an overestimation
                 of the amount of explained variance. Correcting these problems
                 will greatly improve the performance of this very useful
                 method in ecological modeling. To prevent the first problem,
                 we propose a two-step procedure. First, a global test using
                 all explanatory variables is carried out. If, and only if, the
                 global test is significant, one can proceed with forward
                 selection. To prevent overestimation of the explained
                 variance, the forward selection has to be carried out with two
                 stopping criteria: (1) the usual alpha significance level and
                 (2) the adjusted coefficient of multiple determination (Ra(2))
                 calculated using all explanatory variables. When forward
                 selection identifies a variable that brings one or the other
                 criterion over the fixed threshold, that variable is rejected,
                 and the procedure is stopped. This improved method is
                 validated by simulations involving univariate and multivariate
                 response data. An ecological example is presented using data
                 from the Bryce Canyon National Park, Utah, U.S.A.",
  journal     = "Ecology",
  publisher   = "Eco Soc America",
  volume      =  89,
  number      =  9,
  pages       = "2623--2632",
  month       =  sep,
  year        =  2008
}