Thank you very much Thierry.
Manuel
El lun., 20 may. 2019 a las 8:59, Thierry Onkelinx (<
thierry.onkelinx at inbo.be>) escribi?:
Aggregating the data will remove al lot of information. And might
introduce bias in case of an unbalanced design.
You need to think about the (combination of) variables which have a
effect. (1|plot) + (1|plot:hour) assumes a plot effect and an effect of
each combination of plot and hour, but no common hour effect.
Days are nested in months. The corresponding random effect is (1|month) +
(1|month:day). You have (1|day) + (1|day:month) which is nonsense.
You really need to do some reading on mixed models. I recommend Zuur et
(2009) Mixed Effects Models and Extensions in Ecology with R
ir. Thierry Onkelinx
Statisticus / Statistician
Vlaamse Overheid / Government of Flanders
INSTITUUT VOOR NATUUR- EN BOSONDERZOEK / RESEARCH INSTITUTE FOR NATURE
FOREST
Team Biometrie & Kwaliteitszorg / Team Biometrics & Quality Assurance
thierry.onkelinx at inbo.be
Havenlaan 88 bus 73, 1000 Brussel
www.inbo.be
///////////////////////////////////////////////////////////////////////////////////////////
To call in the statistician after the experiment is done may be no more
than asking him to perform a post-mortem examination: he may be able to
what the experiment died of. ~ Sir Ronald Aylmer Fisher
The plural of anecdote is not data. ~ Roger Brinner
The combination of some data and an aching desire for an answer does not
ensure that a reasonable answer can be extracted from a given body of
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<https://www.inbo.be>
Op ma 20 mei 2019 om 16:07 schreef Salvador S?nchez-Col?n <
salvadorsanchezcolon at prodigy.net.mx>:
Hola Manuel:
If you are not interested in examining the between-hours or between-days
variability, then you might consider analyzing the average of your
values and thus simplify the model.
Best regards,
Salvador
Salvador S?NCHEZ-COL?N
On May 20, 2019, at 8:54 AM, Manuel Sp?nola <mspinola10 at gmail.com>
Thank you very much Thierry.
I just only want to accomodate the nested repeated measure of my
I measure the index at the same plot, several times in an hour,
days and during several month.
3 "habitats", within each habitat 12 plots, and on each plot I
index several times, within hours, several days and several months.
I am not interested in the evolution of the index in time, just to
for the repeated measure of my design (I measured the index hundreds
time on each plot).
Maybe I don't need to worry about hour, day and month?
Manuel
El lun., 20 may. 2019 a las 2:00, Thierry Onkelinx (<
thierry.onkelinx at inbo.be>) escribi?:
Dear Manuel,
You'll need to think about the structure of your random effects. Your
current random effect structure is (1|plot) + (1|plot:hour) +
(1|plot:hour:day) + (1|plot:hour:day:month). Which might not be what
had in mind.
Best regards,
ir. Thierry Onkelinx
Statisticus / Statistician
Vlaamse Overheid / Government of Flanders
INSTITUUT VOOR NATUUR- EN BOSONDERZOEK / RESEARCH INSTITUTE FOR
FOREST
Team Biometrie & Kwaliteitszorg / Team Biometrics & Quality Assurance
thierry.onkelinx at inbo.be
Havenlaan 88 bus 73, 1000 Brussel
www.inbo.be
///////////////////////////////////////////////////////////////////////////////////////////
To call in the statistician after the experiment is done may be no
than asking him to perform a post-mortem examination: he may be able
what the experiment died of. ~ Sir Ronald Aylmer Fisher
The plural of anecdote is not data. ~ Roger Brinner
The combination of some data and an aching desire for an answer does
ensure that a reasonable answer can be extracted from a given body of
///////////////////////////////////////////////////////////////////////////////////////////
mspinola10 at gmail.com>:
Dear list members,
I am measuring an index in plots, in different hours, different
different months in 3 different "habitats".
12 plots by "habitats".
I would like to estimate the mean index in the 3 environments.
Is this model appropriate to achieve my goal?
model <- lmer(index ~ habitat + (1 | plot/hour/day/month), data =
REML = FALSE)
Best,
Manuel
--
*Manuel Sp?nola, Ph.D.*
Instituto Internacional en Conservaci?n y Manejo de Vida Silvestre
Universidad Nacional
Apartado 1350-3000
Heredia
COSTA RICA
mspinola at una.cr <mspinola at una.ac.cr>
mspinola10 at gmail.com
Tel?fono: (506) 8706 - 4662
Personal website: Lobito de r?o <
https://sites.google.com/site/lobitoderio/>
Institutional website: ICOMVIS <http://www.icomvis.una.ac.cr/>
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