[R] data analysis

[lamack lamack]

Dear all, I have a factorial design where the
response is an ordered categorical response.

treatment (two levels: 1 and 2)
time (four levels: 30, 60,90 and 120)
ordered response (0,1,2,3)

could someone suggest a correct analysis or some references?

Best regards

subject treatment 	time 	 response
1     	1       	30       3
2     	1       	30       3
3     	1       	30       1
4     	1       	30       3
5     	1       	60       3
6     	1       	60       1
7     	1       	60       1
8     	1       	60       2
9     	1       	90       2
10     	1       	90       1
11     	1       	90       1
12     	1       	90       1
13     	1      	120      2
14     	1      	120      1
15     	1      	120      1
16     	1      	120      1
17     	2       	30       3
18     	2       	30       3
19     	2       	30       1
20     	2       	30       1
21     	2       	60       1
22     	2       	60       2
23     	2       	60       1
24     	2       	60       1
25     	2       	90       1
26     	2       	90       1
27     	2       	90       1
28     	2       	90       3
29     	2      	120      1
30     	2      	120      2
31     	2      	120      0
32     	2      	120      1

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