问题描述
在将黄土平滑度和置信度限制拟合到残差散点图时,我遇到了麻烦.
I'm having trouble fitting a loess smooth plus confidence limits to a scatterplot of residuals.
我的模型是身高〜体重+胸围.为了检查胸围的线性度,我拟合了没有胸围的模型(即身高〜体重),并针对胸围绘制了该模型的残差.到目前为止,一切都很好.然后,我尝试使用loess()
和predict()
绘制一条黄土线以及置信度限制.结果看起来像这样(在图片中,我仅绘制了中心线,但CI线看起来相同):
My model is height ~ weight + chest circumference. To check linearity of chest circumference, I've fitted a model without chest circumference (i.e. height ~ weight), and plotted the residuals of this model against chest circumference. So far so good. I then tried to use loess()
and predict()
to plot a loess line, plus confidence limits. The result looks like this (in the picture I've only plotted the central line, but the CI lines look the same):
这些点是正确的(当我将黄土拟合点绘制为看起来正确的点时),但是由于某种原因,该线并未按照我的期望绘制.我的代码如下:
The points are correct (when I plot the loess fit as points it looks right), but for some reason the line is not being drawn how I expect. My code is below:
# bf.red = data set; mod.nch = model; chestc = chest circumference;
# loess = loess model; lo.pred = predict loess
plot(bf.red$chestc #Chest circumference
,residuals(mod.nch)) #Residuals from height ~ weight model
loess <- loess(mod.nch$residuals ~ bf.red$chestc)
lo.pred <- predict(loess, se=T)
lines(bf.red$chestc,lo.pred$fit,pch=2) #Main line
lines(bf.red$chestc,lo.pred$fit+2*lo.pred$s, lty=2) #rough & ready CI
lines(bf.red$chestc,lo.pred$fit-2*lo.pred$s, lty=2)
希望可以为您提供帮助.非常感谢,
Hope you can help. Many thanks,
垫子
推荐答案
lines
以它们出现的顺序连接点,有时是不可取的.您可以对它们进行如下排序:
lines
connects the points in the order in which they appear,which is sometimes undesirable.You can sort them as follows:
i <- order(bf.red$chestc)
lines(bf.red$chestc[i], lo.pred$fit[i])
...
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