ggplot geom_smooth lm中带宽的含义 [英] Meaning of band width in ggplot geom_smooth lm

问题描述

使用以下代码:

library(ggplot2)
ggplot(mtcars, aes(x=wt, y=mpg)) +
    geom_point(aes(colour=factor(cyl))) +
    geom_smooth(method="lm")

我可以得到这个情节:

我的问题是灰色区域是如何定义的?这是什么意思 我该如何使用各种参数来控制波段的宽度?

解决方案

默认情况下，它是线性模型("lm")的预测的95％置信水平区间. ?geom_smooth中的文档指出:

此几何的默认统计信息为 stat_smooth .请参阅该文档，以了解更多控制基础统计转换的选项.

从?stat_smooth中深入研究一层，可以告诉我们有关用于计算平滑器面积的方法.

为获得快速结果，可以使用 stat_smooth 的参数之一，即level:要使用的置信区间级别(默认为0.95)

通过将该参数传递给 geom_smooth ，它依次传递给 stat_smooth ，这样，如果您希望使用更窄的区域，则可以使用例如.90作为置信度:

ggplot(mtcars, aes(x=wt, y=mpg)) +
    geom_point(aes(colour=factor(cyl))) +
    geom_smooth(method="lm", level=0.90)

With the following code:

library(ggplot2)
ggplot(mtcars, aes(x=wt, y=mpg)) +
    geom_point(aes(colour=factor(cyl))) +
    geom_smooth(method="lm")

I can get this plot:

My question is how does the grey zone defined? What's the meaning of it. And how can I play around with various parameter that control the width of that band?

解决方案

By default, it is the 95% confidence level interval for predictions from a linear model ("lm"). The documentation from ?geom_smooth states that:

The default stat for this geom is stat_smooth see that documentation for more options to control the underlying statistical transformation.

Digging one level deeper, doc from ?stat_smooth tells us about the methods used to calculate the smoother's area.

For quick results, one can play with one of the arguments for stat_smooth which is level : level of confidence interval to use (0.95 by default)

By passing that parameter to geom_smooth, it is passed in turn to stat_smooth, so that if you wish to have a narrower region, you could use for instance .90 as a confidence level:

ggplot(mtcars, aes(x=wt, y=mpg)) +
    geom_point(aes(colour=factor(cyl))) +
    geom_smooth(method="lm", level=0.90)

这篇关于ggplot geom_smooth lm中带宽的含义的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！