Dear list members,
I am analyzing a repeated measure design with the nlme package to assess
the disease rate in 48 counties (localidad). The disease rate was
measured in 4 consecutive years. The first 20 observations of my data
set looks like:
> ipa
localidad tiempo ipa
1 15.MILLAS 1 123.40
2 23.MILLAS 1 185.40
3 24.MILLAS 1 21.31
4 25.MILLAS 1 0.00
5 26.MILLAS 1 59.11
6 28.MILLAS 1 10.28
7 4.MILLAS 1 118.69
8 7.MILLAS 1 17.09
9 AGRODISA 1 59.49
10 ASELICA 1 50.98
11 BALTIMORE 1 25.10
12 BANANITA 1 19.30
13 BANASOL 1 0.00
14 BARBILLA 1 27.33
15 BATAN 1 48.58
16 B.LINE 1 57.97
17 BOSTON 1 101.32
18 BRISTOL 1 47.62
19 COLONIA.PURISCALEÑA 1 22.22
20 CORINA 1 22.22
I tried these models:
# Pooled data
modelo1 = glm(ipa ~ tiempo, family=gaussian(link=identity), data=ipa)
summary(modelo1)
# Parallel slopes
modelo2 = glm(ipa ~ tiempo + localidad, family=gaussian(link=identity),
data=ipa)
summary(modelo2)
# Random intercept (el intercepto cambia para cada localidad)
modelo3 = lme(ipa ~ tiempo, random = ~ 1 | localidad, data=ipa)
summary(modelo3)
# Random intercept and slope
modelo4 = lme(ipa ~ tiempo, random = ~ tiempo | localidad, data=ipa)
summary(modelo4)
# Autocorrelation
modelo6 = lme(ipa ~ tiempo, random = ~ 1 | localidad, correlation =
corCAR1(form = ~ tiempo | localidad), data=ipa)
summary(modelo6)
The model for Random intercept and slope gave me this error:
> modelo4 = lme(ipa ~ tiempo, random = ~ tiempo | localidad, data=ipa)
Error en lme.formula(ipa ~ tiempo, random = ~tiempo | localidad, data =
ipa) :
nlminb problem, convergence error code = 1
message = iteration limit reached without convergence (9)
Do you know why the model (modelo4) has problems?
Also, is this the way to analyze a repeated measure design in R?
The counties (localidad) are all the county that I am interested, is
that still random?
Thank you very much in advance.
Best,
Manuel Spínola
--
Manuel Spínola, Ph.D.
Instituto Internacional en Conservación y Manejo de Vida Silvestre
Universidad Nacional
Apartado 1350-3000
Heredia
COSTA RICA
mspin...@una.ac.cr
mspinol...@gmail.com
Teléfono: (506) 2277-3598
Fax: (506) 2237-7036
_______________________________________________
R-sig-ecology mailing list
R-sig-ecology@r-project.org
https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
