Dear all,
I have a question regarding mixed effect models and I have not been
successful in finding the answer in the sites.

I have my response variable "a" and the explanatory variables "distance",
"numberAni" and "factor(algorithms)---with  seven different algorithms, I
also have my random variable "species" (with 5 different species). One of
the algorithms is set as the intercept in the model.

I run my model:

model_1<-(lme(a)~ numberAni*factor(algorithm)+distance*factor(algorithm),
random=~1|species,data=datamodel)

An my summary table is as follows. My question is* why* do I get the *same
Std. Error* for all the algorithms in the first part of the table and then
other same std. error for the first interactions and then the new one for
the second interactions? why are the within groups std. errors the same?


                                    Value  *Std.Error*   DF    t-value p-value
(Intercept)                     1.0676374 0.28408892 4677   3.758110  0.0002
NumberAni                       -0.0001166 0.00022606   13  -0.515724  0.6147
factor(algorithm)A1             -2.8588307 0.14268775 4677 -20.035572  0.0000
factor(algorithm)A2             -0.3869196 0.14268775 4677  -2.711653  0.0067
factor(algorithm)A3             -0.6668651 0.14268775 4677  -4.673597  0.0000
factor(algorithm)A4             -0.6600452 0.14268775 4677  -4.625802  0.0000
factor(algorithm)A5             -0.3995352 0.14268775 4677  -2.800066  0.0051
factor(algorithm)A6             -0.8642987 0.14268775 4677  -6.057273  0.0000
distance                       -0.0000014 0.00000204   13  -0.685703  0.5049

NumberAni:factor(algorithm)A1   0.0007324 0.00010871 4677   6.737032  0.0000

NumberAni:factor(algorithm)A2    0.0003483 0.00010871 4677   3.203698  0.0014

NumberAni:factor(algorithm)A3    0.0004839 0.00010871 4677   4.451614  0.0000

NumberAni:factor(algorithm)A4    0.0004649 0.00010871 4677   4.277108  0.0000

NumberAni:factor(algorithm)A5    -0.0000330 0.00010871 4677  -0.303855  0.7613

NumberAni:factor(algorithm)A6    0.0004812 0.00010871 4677   4.426913  0.0000

factor(algorithm)A1:distance 0.0000085 0.00000099 4677 8.577618 0.0000
factor(algorithm)A2:distance 0.0000023 0.00000099 4677 2.309649 0.0210
factor(algorithm)A3:distance 0.0000024 0.00000099 4677 2.468800 0.0136
factor(algorithm)A4:distance 0.0000030 0.00000099 4677 3.008320 0.0026
factor(algorithm)A5:distance -0.0000001 0.00000099 4677 -0.064863 0.9483
factor(algorithm)A6:distance 0.0000033 0.00000099 4677 3.309633 0.0009



If someone could explain it to me it would be great. I am sorry if this is
a question already answered before.

Regards,

Jag

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