如何在lme中分别拟合两个随机效果? [英] How to fit two random effects separately in lme?

问题描述

我正在nlme软件包中通过REML进行线性混合效果模型拟合.这些是对我有用的代码:

I'm doing Linear mixed-effects model fit by REML in nlme package. And these are codes that work for me:

# Linear mixed-effects model fit by REML (intercept and not slope)
x <- lme (DV ~ IV1 + IV2 + IV1*IV2, data=a.frame, random=~1|speaker)
summary(x)

# Linear mixed-effects model fit by REML (slope and no intercept)
x1 <- lme (DV ~ IV1 + IV2 + IV1*IV2, data=a.frame, random=~IV3-1|speaker)
summary(x1)

# Linear mixed-effects model fit by REML (slope and intercept)
x2 <- lme (DV ~ IV1 + IV2 + IV1*IV2, data=a.frame, random=~IV3|speaker)
summary(x2)

#nested random effect
x5 <- lme (DV ~ IV1 + IV2 + IV1*IV2, data=a.frame, random=~1|speaker/item)
summary(x5)

我真正想做的是建立一个扬声器和物品分别作为随机效果的模型.我曾尝试使用以下公式:

What I really would like to do is having a model with both speaker and item as random effects separately. I had tried to use this formula:

x4 <- lme (DV ~ IV1 + IV2 + IV1*IV2, data=a.frame, random=~1|speaker + 1|item)

但是，此公式给我以下警告消息:

However, this formula gives me the following warning message:

Warning message:
In Ops.factor(speaker, 1) : + not meaningful for factors

您知道这意味着什么吗?我该如何分别将扬声器和项目作为随机效果安装?

Do you have any idea what this means? And how can I fit both speaker and item as random effects separately?

推荐答案

我认为可以使用lme()通过以下代码分别包含两种随机效果(一种用于说话者，一种用于时间):

I think it is possible to include two random effects seperately (one for speaker and one for time) using lme() by the following code:

x4 <- lme (DV ~ IV1 + IV2 + IV1*IV2, data=a.frame, random=~ speaker + item -1 | id),

和id是一个更高级别的变量，其中同时嵌套了speaker和item.如果没有这样的变量，则可以将其作为所有变量的值为1的新变量引入.

with id a higher level variable in which both speaker and item are nested. If you don't have such a variable, you could introduce it as a new variable with value 1 for all observations.

这篇关于如何在lme中分别拟合两个随机效果?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！