[R] p values of lmer

[peter dalgaard]

On Jun 19, 2013, at 15:02 , R. Michael Weylandt wrote:

> On Wed, Jun 19, 2013 at 10:27 AM, meng <laomeng_3 at 163.com> wrote:
>> Hi all:
>> I met a question about lmer.
>> 
>> fm1 <- lmer(Reaction ~ Days + (Days|Subject), sleepstudy)
>> summary(fm1)
>> 
>> ...
>> 
>> Fixed effects:
>>            Estimate Std. Error t value
>> (Intercept)  251.405      6.825   36.84
>> Days          10.467      1.546    6.77
>> 
>> ...
>> 
>> My question:
>> Why p values of (Intercept) and Days are not given?
> 
> Take a look at R FAQ 7.35.
> 
> http://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-are-p_002dvalues-not-displayed-when-using-lmer_0028_0029_003f
> 
> 

That's getting a bit old. It has a reference to Doug Bates posting from 2006, which basically says "because degree of freedom issues are unresolved". 

Important developments have happened since, and Rune's reference to package lmerTest (and, implicitly, pbkrtest) is more precise these days. 

-- 
Peter Dalgaard, Professor
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com