[R] setting up LMER for repeated measures and how do I get a p value for my fixed effect, group?

[Kingsford Jones]

On Thu, Jul 23, 2009 at 12:36 PM, Kingsford
Jones<kingsfordjones at gmail.com> wrote:

>
> As you might have suspected from the lmer t-value close to 0, the
> associated p-value is about .5.

you can ignore the sentence above -- it's a two sided test and the
t-value is not that close to 0...

>
> hth,
>
> Kingsford Jones
>
>> My subjects are divided into two groups (variable GROUP), individual subjects are indicated by the variable SS, Value is the outcome measure, each subject has Value measured three times.
>>
>> I have used the following code:
>>
>> fit1<-lmer(Value~Group+(1|SS),data=smallDS)
>> print(fit1)
>>
>> Linear mixed model fit by REML
>> Formula: Value ~ Group + (1 | SS)
>>   Data: Dataset
>>   AIC   BIC logLik deviance REMLdev
>>  284.8 290.4 -138.4    291.4   276.8
>> Random effects:
>>  Groups   Name        Variance Std.Dev.
>>  SS       (Intercept) 1038.0   32.218
>>  Residual              552.7   23.510
>> Number of obs: 30, groups: SS, 10
>>
>> Fixed effects:
>>                        Estimate Std. Error t value
>> (Intercept)               152.87      15.63   9.778
>> Group[T.ContSIRNAnoEGF]   -15.87      22.11  -0.718
>>
>> Correlation of Fixed Effects:
>>            (Intr)
>> G[T.CSIRNAE -0.707
>>
>>
>> Questions:
>> (1) Have I set up lmer properly to analyze the repeated measures data?
>> (2) How can I get a p value for Group, my fixed effect?
>>
>>
>>
>>      Group SS Value
>>  [1,]     2  1   127
>>  [2,]     2  1   179
>>  [3,]     2  1   159
>>  [4,]     2  2   186
>>  [5,]     2  2   173
>>  [6,]     2  2   178
>>  [7,]     2  3   117
>>  [8,]     2  3   116
>>  [9,]     2  3    70
>> [10,]     2  4   176
>> [11,]     2  4   149
>> [12,]     2  4   138
>> [13,]     2  5   100
>> [14,]     2  5   105
>> [15,]     2  5    82
>> [16,]     1  6   142
>> [17,]     1  6   195
>> [18,]     1  6   222
>> [19,]     1  7   218
>> [20,]     1  7   178
>> [21,]     1  7   147
>> [22,]     1  8   135
>> [23,]     1  8   162
>> [24,]     1  8   177
>> [25,]     1  9   104
>> [26,]     1  9   102
>> [27,]     1  9   121
>> [28,]     1 10   135
>> [29,]     1 10   121
>> [30,]     1 10   134
>>
>>
>> John David Sorkin M.D., Ph.D.
>> Chief, Biostatistics and Informatics
>> University of Maryland School of Medicine Division of Gerontology
>> Baltimore VA Medical Center
>> 10 North Greene Street
>> GRECC (BT/18/GR)
>> Baltimore, MD 21201-1524
>> (Phone) 410-605-7119
>> (Fax) 410-605-7913 (Please call phone number above prior to faxing)
>>
>> Confidentiality Statement:
>> This email message, including any attachments, is for th...{{dropped:6}}
>>
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>> and provide commented, minimal, self-contained, reproducible code.
>>
>