如果有问题的变量不是在外 lmer，有没有办法在false内指定对比度矩阵？作为示例，具有组的2×4混合模型的玩具数据，受试者之间的因子和受试者内因子的时间。我在时间水平上测试组间的分组差异，但这更多是一个技术问题，关于是否可以将数值变量指定为lmer内的因子（即，将它们保持为数字外的数字） lmer）。
lmer请注意，set.seed(345)
A0 <- rnorm(4,2,.5)
B0 <- rnorm(4,2+3,.5)
A1 <- rnorm(4,6,.5)
B1 <- rnorm(4,6+2,.5)
A2 <- rnorm(4,10,.5)
B2 <- rnorm(4,10+1,.5)
A3 <- rnorm(4,14,.5)
B3 <- rnorm(4,14+0,.5)
score <- c(A0,B0,A1,B1,A2,B2,A3,B3)
id <- rep(1:8,times = 4, length = 32)
time <- rep(0:3, each = 8, length = 32)
group <- rep(c("A","B"), times =2, each = 4, length = 32)
df <- data.frame(id = id, group = group, time = time, score = score)
因子是一个数字变量，已包含在time命令中的模型中。
factor()这本身就可以正常使用。但是，当我使用相同的summary(lmer(score ~ group*factor(time) + (1|id), data = df))
语法指定contrasts时：
factor(time)我收到错误：
summary(lmer(score ~ group*factor(time) + (1|id), data = df, contrasts = list(factor(time) = contr.helmert(4), group = contr.helmert(2))))
...我假设是指定Error: unexpected '=' in "summary(lmer(score ~ group*factor(time) + (1|id), data = df, contrasts = list(factor(time) ="
命令中time变量的对比矩阵。
如果我没有在factor()来电中致电time一个因素......
contrasts =它会返回一个结果，但会忽略该因子，并显示警告消息....
summary(lmer(score ~ group*factor(time) + (1|id), data = df, contrasts = list(time = contr.helmert(4), group = contr.helmert(2))))
我知道我在这里违反了1: In model.matrix.default(fixedform, fr, contrasts) :
variable 'time' is absent, its contrast will be ignored
2: In model.matrix.default(fixedform, fr, contrasts) :
variable 'time' is absent, its contrast will be ignored
3: In model.matrix.default(fixedform, fr, contrasts) :
variable 'time' is absent, its contrast will be ignored
4: In model.matrix.default(fixedform, fr, contrasts) :
variable 'time' is absent, its contrast will be ignored
5: In model.matrix.default(fixedform, fr, contrasts) :
variable 'time' is absent, its contrast will be ignored
6: In model.matrix.default(fixedform, fr, contrasts) :
variable 'time' is absent, its contrast will be ignored
7: In model.matrix.default(fixedform, fr, contrasts) :
variable 'time' is absent, its contrast will be ignored
8: In model.matrix.default(fixedform, fr, contrasts) :
variable 'time' is absent, its contrast will be ignored
9: In model.matrix.default(fixedform, fr, contrasts) :
variable 'time' is absent, its contrast will be ignored
10: In model.matrix.default(fixedform, fr, contrasts) :
variable 'time' is absent, its contrast will be ignored
的语法，但我试图证明我将喜欢实现的目标，同时承认我不知道如何这样做或者如果我想做的话甚至是可能的。