Hello,
Iīve got to confess that my R knowledge is very basic and I have a problem
with a data set for what I am supposed to do a repeated measures anova and a
glmm. Iīve been all over the help lists and really tried quite a time but
there seems to be a mistake within my arrangement of data so I would be
really really glad if somebody with a bit more experience could look over
this and help me out.
Generaly the study was about a stream restoration. At three different point
of times I made measurements of Dissolved Oxygen, pH,
conductivity,Nitrate,Nitrite,Ammonium, redox potential in 5 cm depth,10 cm,
15 cm, and free flowing water to see how these values change over time. I
took this data on 4 sites for each date so that for each date I have a set
of data that contains 4 values of Oxygen in 5cm, 10 cm.....and all the same
for the other parameters. What I tried to start with was a repeated measures
anova to see whether there are differences among the different dates of data
collection at all, concerning each of the parameters.
For example for Oxygen I arranged the data like this:
5.11 25.11 9.3
Site 1
5cm 9.24 9 .46 9.74
10cm 9.05 9.37 9.30
15cm 2.83 8.37 9.73
FW 9.91 9.55 9.85
And so on......
Site2
5cm 9.48 9.04 9.78
10cm 4.47 8.99 9.53
15cm 4.71 7.74 8.77
FW 10.01 9.37 9.82
Site3
5cm 5.38 9,28 9.56
10cm 6.31 8.49 9.11
15cm 6.36 8.91 9.44
FW 9.97 9.55 9.89
Site4
5cm 9.86 9.00 9.87
10cm 4.82 8.93 9.13
15cm 4.41 8.69 7.32
FW 10.01 9.62 9.89
I arranged the data like this, so that every detph level has a capital
letter and the numbers from time stand for the different dates:
subj time Do
A 1 9.24
A 2 9.46
A 3 9.74
B 1 9.05
B 2 9.37
B 3 9.30
C 1 2.83
C 2 8.37
C 3 9.73
D 1 9.91
D 2 9.55
D 3 9.85
E 1 9.48
E 2 9.04
E 3 9.78
F 1 4.47
F 2 8.99
F 3 9.53
G 1 4.71
G 2 7.74
G 3 8.77
H 1 10.01
H 2 9.37
H 3 9.82
I 1 5.38
I 2 9,28
I 3 9.56
J 1 6.31
J 2 8.49
J 3 9.11
K 1 6.36
K 2 8.91
K 3 9.44
L 1 9.97
L 2 9.55
L 3 9.89
M 1 9.86
M 2 9.00
M 3 9.87
N 1 4.82
N 2 8.93
N 3 9.13
O 1 4.41
O 2 8.69
O 3 7.32
P 1 10.01
P 2 9.62
P 3 9.89
I tried to do the repeated measures anova as follows:
lme(Do~time,random=~/subj)
But that did not really work. Generally Iīm not that interested in the
different depth levels, I going to analyse that differently anyway . I just
wanted to give it a try in the lme function. But it would be great to have
a working repeated measures anova for analysing whether there are
differences between the different dates for all of the parameters.
Concerning the glmm I tried to get into this and read papers and help lists
articles but I have the feeling that this definetely exceeds my statistical
knowledge and if was hoping if someone could help me get an idea of how to
fit this data set in such a model. The problem starts that i donīt really
see what could be my response variable if not the time factor as there is
nothing from this data set that all the other parameters depend on. But I
donīt know how to fit the time/date factor in such a model.
I know this is probabls something rather trivial but as i said the
experience is lacking and help would take me a big big step closer to
getting this bachelor thesis done so thanks a lot to everybody who is
willing to look at this problem.
Thanks a lot and best regards ,
Romy Wild
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