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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><title>R: Regression diagnostics for trend surfaces</title> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <link rel="stylesheet" type="text/css" href="R.css" /> </head><body> <table width="100%" summary="page for trls.influence {spatial}"><tr><td>trls.influence {spatial}</td><td style="text-align: right;">R Documentation</td></tr></table> <h2> Regression diagnostics for trend surfaces </h2> <h3>Description</h3> <p>This function provides the basic quantities which are used in forming a variety of diagnostics for checking the quality of regression fits for trend surfaces calculated by <code>surf.ls</code>. </p> <h3>Usage</h3> <pre> trls.influence(object) ## S3 method for class 'trls' plot(x, border = "red", col = NA, pch = 4, cex = 0.6, add = FALSE, div = 8, ...) </pre> <h3>Arguments</h3> <table summary="R argblock"> <tr valign="top"><td><code>object, x</code></td> <td> <p>Fitted trend surface model from <code>surf.ls</code> </p> </td></tr> <tr valign="top"><td><code>div</code></td> <td> <p>scaling factor for influence circle radii in <code>plot.trls</code> </p> </td></tr> <tr valign="top"><td><code>add</code></td> <td> <p>add influence plot to existing graphics if <code>TRUE</code> </p> </td></tr> <tr valign="top"><td><code>border, col, pch, cex, ...</code></td> <td> <p>additional graphical parameters </p> </td></tr> </table> <h3>Value</h3> <p><code>trls.influence</code> returns a list with components: </p> <table summary="R valueblock"> <tr valign="top"><td><code>r</code></td> <td> <p>raw residuals as given by <code>residuals.trls</code> </p> </td></tr> <tr valign="top"><td><code>hii</code></td> <td> <p>diagonal elements of the Hat matrix </p> </td></tr> <tr valign="top"><td><code>stresid</code></td> <td> <p>standardised residuals </p> </td></tr> <tr valign="top"><td><code>Di</code></td> <td> <p>Cook's statistic </p> </td></tr> </table> <h3>References</h3> <p>Unwin, D. J., Wrigley, N. (1987) Towards a general-theory of control point distribution effects in trend surface models. <em>Computers and Geosciences,</em> <b>13</b>, 351–355. </p> <p>Venables, W. N. and Ripley, B. D. (2002) <em>Modern Applied Statistics with S.</em> Fourth edition. Springer. </p> <h3>See Also</h3> <p><code><a href="surf.ls.html">surf.ls</a></code>, <code><a href="../../stats/html/influence.measures.html">influence.measures</a></code>, <code><a href="../../stats/html/plot.lm.html">plot.lm</a></code> </p> <h3>Examples</h3> <pre> library(MASS) # for eqscplot data(topo, package = "MASS") topo2 <- surf.ls(2, topo) infl.topo2 <- trls.influence(topo2) (cand <- as.data.frame(infl.topo2)[abs(infl.topo2$stresid) > 1.5, ]) cand.xy <- topo[as.integer(rownames(cand)), c("x", "y")] trsurf <- trmat(topo2, 0, 6.5, 0, 6.5, 50) eqscplot(trsurf, type = "n") contour(trsurf, add = TRUE, col = "grey") plot(topo2, add = TRUE, div = 3) points(cand.xy, pch = 16, col = "orange") text(cand.xy, labels = rownames(cand.xy), pos = 4, offset = 0.5) </pre> <hr /><div style="text-align: center;">[Package <em>spatial</em> version 7.3-11 <a href="00Index.html">Index</a>]</div> </body></html>