Dear Experts,

I am new to R and unfortunately cannot start with a simply statistical  
analysis:

I manually determined the volume of the right and left hippocampus in  
a group of meditators and in a group of controls. My data-sheet looks  
as follows:


observation	subject	group	age	gender	hemisphere	volume
1	am04	m	25	f	left	3.637
2	am04	m	25	f	right	3.713
3	ao08	m	47	m	left	3.715
4	ao08	m	47	m	right	3.702
5	as11	m	43	f	left	3.912
6	as11	m	43	f	right	4.438
7	bn02	c	30	f	left	4.497
8	bn02	c	30	f	right	4.333
9	ca15	c	46	m	left	3.346
10	ca15	c	46	m	right	3.779
11	cd13	m	41	m	left	4.167
12	cd13	m	41	m	right	4.184
13	dk09	m	45	m	left	4.289
14	dk09	m	45	m	right	4.457
15	dm08	c	42	m	left	4.084
16	dm08	c	42	m	right	3.572
17	donf55	c	47	m	left	4.006
18	donf55	c	47	m	right	4.211
19	dr01	c	28	m	left	3.717
20	dr01	c	28	m	right	3.660
21	ds17	m	46	m	left	4.140
22	ds17	m	46	m	right	4.157
23	dts14	m	30	m	left	4.830
24	dts14	m	30	m	right	5.081
25	eg19	m	46	f	left	4.679
26	eg19	m	46	f	right	4.123
27	em12	m	33	m	left	4.183
28	em12	m	33	m	right	4.671
29	ew10	m	48	m	left	4.074
30	ew10	m	48	m	right	4.133
31	harp74	c	29	f	left	4.449
32	harp74	c	29	f	right	4.505
33	ih18	m	26	f	left	4.859
34	ih18	m	26	f	right	4.635
35	jk20	c	26	f	left	4.765
36	jk20	c	26	f	right	4.582
37	jl22	m	29	m	left	4.798
38	jl22	m	29	m	right	4.970
39	jm05	c	24	m	left	4.177
40	jm05	c	24	m	right	3.878
41	jp16	c	49	m	left	4.541
42	jp16	c	49	m	right	4.468
43	kr16	m	28	f	left	5.193
44	kr16	m	28	f	right	5.367
45	ln06	m	31	f	left	5.283
46	ln06	m	31	f	right	5.971
47	ls06	c	29	f	left	4.462
48	ls06	c	29	f	right	4.517
49	md02	m	50	m	left	4.733
50	md02	m	50	m	right	4.456
51	rp19	c	33	m	left	4.572
52	rp19	c	33	m	right	4.270
53	rs20	m	49	m	left	5.410
54	rs20	m	49	m	right	5.275
55	sinj55	c	49	f	left	4.634
56	sinj55	c	49	f	right	4.883
57	sm21	m	42	f	left	4.499
58	sm21	m	42	f	right	4.317
59	sw04	c	34	m	left	3.956
60	sw04	c	34	m	right	4.303
61	sy15	m	40	m	left	4.429
62	sy15	m	40	m	right	4.550
63	ts14	c	46	m	left	4.233
64	ts14	c	46	m	right	4.568
65	wi18	c	35	m	left	5.101
66	wi18	c	35	m	right	5.317
67	ws01	m	30	m	left	5.221
68	ws01	m	30	m	right	5.258
69	zz03	m	35	m	left	4.446
70	zz03	m	35	m	4.446	4.627
My attempt to compute the according statistic was:

aov = aov(volume~(hemisphere*group)+Error(subject/hemisphere)+ 
(group),input)

but with this I got the following error message:

In aov(volume ~ (hemisphere * group) + Error(subject/hemisphere) +  :
   Error() Modell ist singulär

I could not figure out what I did wrong. Furthermore, in the next step  
I would like to use gender and age as additional covariates in the  
model, but I am not sure how to do this either.

  Any help would be very much appreciated!

Thank you,

Sincerely,

Lucas Eggert




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