[R-sig-ME] p-values from lme::anova VS fixed-effects of lme

[K Imran M]

Dear all,


Firstly, my apology if this question is trivial. This question is related
to this post at
http://stats.stackexchange.com/questions/7185/what-is-the-difference-between-using-aov-and-lme-in-analyzing-a-longitudinal
.


My I ask a question is: If I rerun these codes (lme)


#### LME ######

res <- lme(distance ~ age*Sex, random = ~ 1 | Subject, data = Orthodont)

summary(res)

################


I would obtain this

#####################################################

Fixed effects: distance ~ age * Sex

                  Value Std.Error DF   t-value p-value

(Intercept)   16.340625 0.9813122 79 16.651810  0.0000

age            0.784375 0.0775011 79 10.120823  0.0000

SexFemale      1.032102 1.5374208 25  0.671321  0.5082

age:SexFemale -0.304830 0.1214209 79 -2.510520  0.0141

########################################################


Next, if I run 'anova(res)', I would obtain this


###ANOVA####

           numDF denDF  F-value p-value

(Intercept)     1    79 4123.156  <.0001

age             1    79  122.450  <.0001

Sex             1    25    9.292  0.0054

age:Sex         1    79    6.303  0.0141

###############


I do not understand why the p-values for age and age:Sex (from anova) are
similar with (lme::anova) BUT for sex: it is different (anova, p-val =
0.0054 vs lme::anova, p-val = 0.508).


Your kind attention is very much appreciated.


Thanks and best wishes,


Kamarul
-- 
Dr. Kamarul Imran Musa (MD MCommunityMed)
Associate Professor (Epidemiology and Biostatistics) &
Public Health Physician,

Address:
Dept of Community Medicine,
School of Medical Sciences,
Universiti Sains Malaysia,
16150 Kbg Kerian Kelantan
MALAYSIA

ResearcherID: http://www.researcherid.com/rid/N-3198-2015
Google-scholar: 'Kamarul Imran Musa'  at https://goo.gl/D3o3y6
ORCID ID: orcid.org/0000-0002-3708-0628
ScopusID: 18634847200
Personal web: www.myanalytics.com.my
Alt emails : drkamarul at usm.my , k.musa at lancaster.ac.uk

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