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en:monte_carlo_r

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en:monte_carlo_r [2019/01/26 20:00] David Zelený |
en:monte_carlo_r [2019/02/10 16:04] David Zelený [R functions] |
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[[{|width: 7em; background-color: white; color: navy}monte_carlo_exercise|Exercise {{::lock-icon.png?nolink|}}]] | [[{|width: 7em; background-color: white; color: navy}monte_carlo_exercise|Exercise {{::lock-icon.png?nolink|}}]] | ||

- | ==== R functions ==== | + | |

- | * **''anova.cca''** (library ''vegan'') - tests the significance of the variation in species composition explained by explanatory variables in constrained ordination (RDA, CCA), using Monte Carlo permutation test. It can test the significance of | + | |

- | * the global model (default setting), i.e. all variables included in the analysis; | + | |

- | * only the first constrained axis (adding argument ''first = TRUE''); | + | |

- | * individual axes (''by = "axis"''), sequentially from the first to the last (this is done by using samples scores on the //n//-th axis as explanatory variables, while using scores of the axis 1, 2, ... //n// as covariables); | + | |

- | * individual terms (explanatory variables) added sequentially in the order in which they appear in the formula or data frame (''by = "terms"''; note that this variation depends on the order of variables in which they enter the model); | + | |

- | * variation explained by individual explanatory variables after removing variation of all other variables in the model (''by = "margin"''; here the variation does not depend on the order of variables in the model). | + |

en/monte_carlo_r.txt · Last modified: 2019/02/10 16:04 by David Zelený