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Does anyone know how to use (nlme)? I'm having a lot of problems using it for something that should be really simple, any help would be really appreciated. I won't put up the details until I know someone knows what I'm talking about.

Data was collected by a field study concerned planting pattern, genotype, we replicated this study for 3 years and in each growing season we surveyd 10 times. My question is how to interpret the results best? A professor advised using linear mixed effect model with year as a random factor, to reduce the number of separate analyses and type I error. Anybody who knows, please do me a favor.

The following is my data

site    YEAR    GENOTYPE    PATTERN T   density
1   1   G   S   T1  3.0035 
2   1   G   S   T1  3.0538 
3   1   G   S   T1  2.9939 
4   1   G   S   T1  2.8506 
5   1   G   M   T1  2.7316 
6   1   G   M   T1  2.7789 
7   1   G   M   T1  2.8791 
8   1   G   M   T1  2.7419 
9   1   S   S   T1  0.6024 
10  1   S   S   T1  0.6079 
11  1   S   S   T1  0.6014 
12  1   S   S   T1  0.5855 
13  1   S   M   T1  0.5719 
14  1   S   M   T1  0.5774 
15  1   S   M   T1  0.5887 
16  1   S   M   T1  0.5731 
1   2   G   S   T1  3.3064 
2   2   G   S   T1  3.2896 
3   2   G   S   T1  3.3448 
4   2   G   S   T1  3.4615 
5   2   G   M   T1  3.4104 
6   2   G   M   T1  3.3243 
7   2   G   M   T1  3.3477 
8   2   G   M   T1  3.4031 
9   2   S   S   T1  3.3660 
10  2   S   S   T1  3.3025 
11  2   S   S   T1  3.3760 
12  2   S   S   T1  3.3038 
13  2   S   M   T1  3.4237 
14  2   S   M   T1  3.5357 
15  2   S   M   T1  3.5001 
16  2   S   M   T1  3.4195 
1   3   G   S   T1  2.2068 
2   3   G   S   T1  2.1492 
3   3   G   S   T1  2.0969 
4   3   G   S   T1  2.3010 
5   3   G   M   T1  1.7404 
6   3   G   M   T1  1.8388 
7   3   G   M   T1  1.5185 
8   3   G   M   T1  1.6128 
9   3   S   S   T1  2.3636 
10  3   S   S   T1  2.5092 
11  3   S   S   T1  2.0828 
12  3   S   S   T1  2.4065 
13  3   S   M   T1  1.9243 
14  3   S   M   T1  2.0645 
15  3   S   M   T1  2.0000 
16  3   S   M   T1  2.0170 
1   1   G   S   T2  3.6379 
2   1   G   S   T2  3.5680 
3   1   G   S   T2  3.6095 
4   1   G   S   T2  3.6999 
5   1   G   M   T2  3.4241 
6   1   G   M   T2  3.5053 
7   1   G   M   T2  3.4559 
8   1   G   M   T2  3.4751 
9   1   S   S   T2  0.6663 
10  1   S   S   T2  0.6597 
11  1   S   S   T2  0.6637 
12  1   S   S   T2  0.6721 
13  1   S   M   T2  0.6458 
14  1   S   M   T2  0.6537 
15  1   S   M   T2  0.6489 
16  1   S   M   T2  0.6508 
1   2   G   S   T2  4.5387 
2   2   G   S   T2  4.5442 
3   2   G   S   T2  4.5174 
4   2   G   S   T2  4.5464 
5   2   G   M   T2  4.3512 
6   2   G   M   T2  4.4067 
7   2   G   M   T2  4.4090 
8   2   G   M   T2  4.1965 
9   2   S   S   T2  4.5641 
10  2   S   S   T2  4.5103 
11  2   S   S   T2  4.6466 
12  2   S   S   T2  4.5205 
13  2   S   M   T2  4.4246 
14  2   S   M   T2  4.3424 
15  2   S   M   T2  4.4487 
16  2   S   M   T2  4.3642 
1   3   G   S   T2  3.0099 
2   3   G   S   T2  3.0730 
3   3   G   S   T2  2.9657 
4   3   G   S   T2  3.1807 
5   3   G   M   T2  2.6812 
6   3   G   M   T2  2.3729 
7   3   G   M   T2  2.8820 
8   3   G   M   T2  2.4800 
9   3   S   S   T2  3.1364 
10  3   S   S   T2  3.0839 
11  3   S   S   T2  2.9036 
12  3   S   S   T2  2.9850 
13  3   S   M   T2  2.7412 
14  3   S   M   T2  2.8202 
15  3   S   M   T2  2.3692 
16  3   S   M   T2  2.5866 
1   1   G   S   T3  3.3762 
2   1   G   S   T3  3.3531 
3   1   G   S   T3  3.5340 
4   1   G   S   T3  3.4096 
5   1   G   M   T3  3.4263 
6   1   G   M   T3  3.1959 
7   1   G   M   T3  3.2973 
8   1   G   M   T3  3.1915 
9   1   S   S   T3  0.6411 
10  1   S   S   T3  0.6388 
11  1   S   S   T3  0.6565 
12  1   S   S   T3  0.6444 
13  1   S   M   T3  0.6460 
14  1   S   M   T3  0.6228 
15  1   S   M   T3  0.6332 
16  1   S   M   T3  0.6224 
1   2   G   S   T3  5.4512 
2   2   G   S   T3  5.3256 
3   2   G   S   T3  5.5334 
4   2   G   S   T3  5.3601 
5   2   G   M   T3  4.9647 
6   2   G   M   T3  5.0390 
7   2   G   M   T3  5.0628 
8   2   G   M   T3  5.0739 
9   2   S   S   T3  5.3199 
10  2   S   S   T3  5.2441 
11  2   S   S   T3  5.2672 
12  2   S   S   T3  5.3007 
13  2   S   M   T3  5.1314 
14  2   S   M   T3  5.0120 
15  2   S   M   T3  5.1177 
16  2   S   M   T3  5.0052 
1   3   G   S   T3  2.8808 
2   3   G   S   T3  3.0839 
3   3   G   S   T3  2.7931 
4   3   G   S   T3  2.8555 
5   3   G   M   T3  2.6902 
6   3   G   M   T3  2.7723 
7   3   G   M   T3  2.8293 
8   3   G   M   T3  2.9299 
9   3   S   S   T3  2.5911 
10  3   S   S   T3  2.5587 
11  3   S   S   T3  2.7818 
12  3   S   S   T3  2.7332 
13  3   S   M   T3  2.8414 
14  3   S   M   T3  2.7024 
15  3   S   M   T3  2.6955 
16  3   S   M   T3  2.9365 
1   1   G   S   T4  2.9309 
2   1   G   S   T4  2.9186 
3   1   G   S   T4  3.0249 
4   1   G   S   T4  3.0910 
5   1   G   M   T4  2.9745 
6   1   G   M   T4  2.9538 
7   1   G   M   T4  3.1179 
8   1   G   M   T4  3.0588 
9   1   S   S   T4  0.5945 
10  1   S   S   T4  0.5931 
11  1   S   S   T4  0.6048 
12  1   S   S   T4  0.6118 
13  1   S   M   T4  0.5993 
14  1   S   M   T4  0.5970 
15  1   S   M   T4  0.6147 
16  1   S   M   T4  0.6084 
1   2   G   S   T4  5.3077 
2   2   G   S   T4  5.4044 
3   2   G   S   T4  5.4797 
4   2   G   S   T4  5.4220 
5   2   G   M   T4  5.1803 
6   2   G   M   T4  5.2498 
7   2   G   M   T4  5.3166 
8   2   G   M   T4  5.2693 
9   2   S   S   T4  5.7061 
10  2   S   S   T4  5.4886 
11  2   S   S   T4  5.5974 
12  2   S   S   T4  5.6148 
13  2   S   M   T4  5.3078 
14  2   S   M   T4  5.1670 
15  2   S   M   T4  5.1887 
16  2   S   M   T4  5.2186 
1   3   G   S   T4  4.1525 
2   3   G   S   T4  4.1609 
3   3   G   S   T4  4.1169 
4   3   G   S   T4  4.1687 
5   3   G   M   T4  3.9305 
6   3   G   M   T4  3.9376 
7   3   G   M   T4  3.9668 
8   3   G   M   T4  3.9696 
9   3   S   S   T4  4.1293 
10  3   S   S   T4  4.1358 
11  3   S   S   T4  4.1450 
12  3   S   S   T4  4.1527 
13  3   S   M   T4  3.8382 
14  3   S   M   T4  3.8435 
15  3   S   M   T4  3.8405 
16  3   S   M   T4  3.8439 
1   1   G   S   T5  3.2206 
2   1   G   S   T5  3.0726 
3   1   G   S   T5  3.0228 
4   1   G   S   T5  3.1284 
5   1   G   M   T5  2.6253 
6   1   G   M   T5  2.7760 
7   1   G   M   T5  2.7774 
8   1   G   M   T5  2.7388 
9   1   S   S   T5  0.6254 
10  1   S   S   T5  0.6099 
11  1   S   S   T5  0.6045 
12  1   S   S   T5  0.6158 
13  1   S   M   T5  0.5593 
14  1   S   M   T5  0.5770 
15  1   S   M   T5  0.5772 
16  1   S   M   T5  0.5727 
1   2   G   S   T5  3.6946 
2   2   G   S   T5  3.7158 
3   2   G   S   T5  3.6597 
4   2   G   S   T5  3.6553 
5   2   G   M   T5  3.5065 
6   2   G   M   T5  3.3351 
7   2   G   M   T5  3.4609 
8   2   G   M   T5  3.3047 
9   2   S   S   T5  3.5875 
10  2   S   S   T5  3.4774 
11  2   S   S   T5  3.5924 
12  2   S   S   T5  3.5771 
13  2   S   M   T5  3.2695 
14  2   S   M   T5  3.3753 
15  2   S   M   T5  3.2916 
16  2   S   M   T5  3.2804 
1   3   G   S   T5  3.6772 
2   3   G   S   T5  3.6558 
3   3   G   S   T5  3.6118 
4   3   G   S   T5  3.6636 
5   3   G   M   T5  3.3967 
6   3   G   M   T5  3.4834 
7   3   G   M   T5  3.3992 
8   3   G   M   T5  3.6731 
9   3   S   S   T5  3.6242 
10  3   S   S   T5  3.6307 
11  3   S   S   T5  3.6396 
12  3   S   S   T5  3.6069 
13  3   S   M   T5  3.4087 
14  3   S   M   T5  3.4874 
15  3   S   M   T5  3.3094 
16  3   S   M   T5  3.6386 
1   1   G   S   T6  2.7332 
2   1   G   S   T6  2.6684 
3   1   G   S   T6  2.8573 
4   1   G   S   T6  2.6365 
5   1   G   M   T6  2.2788 
6   1   G   M   T6  2.4624 
7   1   G   M   T6  2.4728 
8   1   G   M   T6  2.3365 
9   1   S   S   T6  0.5721 
10  1   S   S   T6  0.5645 
11  1   S   S   T6  0.5863 
12  1   S   S   T6  0.5607 
13  1   S   M   T6  0.5157 
14  1   S   M   T6  0.5394 
15  1   S   M   T6  0.5407 
16  1   S   M   T6  0.5233 
1   2   G   S   T6  3.0955 
2   2   G   S   T6  3.0941 
3   2   G   S   T6  3.1123 
4   2   G   S   T6  3.0821 
5   2   G   M   T6  2.8195 
6   2   G   M   T6  2.8609 
7   2   G   M   T6  2.9085 
8   2   G   M   T6  2.9745 
9   2   S   S   T6  3.0465 
10  2   S   S   T6  2.9566 
11  2   S   S   T6  3.0422 
12  2   S   S   T6  2.9360 
13  2   S   M   T6  2.9494 
14  2   S   M   T6  2.9652 
15  2   S   M   T6  2.9309 
16  2   S   M   T6  3.0000 
1   3   G   S   T6  2.9079 
2   3   G   S   T6  2.8768 
3   3   G   S   T6  2.7882 
4   3   G   S   T6  2.9689 
5   3   G   M   T6  2.7259 
6   3   G   M   T6  2.6875 
7   3   G   M   T6  2.5340 
8   3   G   M   T6  2.6170 
9   3   S   S   T6  2.0934 
10  3   S   S   T6  2.0043 
11  3   S   S   T6  2.0043 
12  3   S   S   T6  2.2201 
13  3   S   M   T6  2.3927 
14  3   S   M   T6  2.4786 
15  3   S   M   T6  2.5453 
16  3   S   M   T6  2.4928 
1   1   G   S   T7  2.7459 
2   1   G   S   T7  2.6503 
3   1   G   S   T7  2.6222 
4   1   G   S   T7  2.7143 
5   1   G   M   T7  2.7348 
6   1   G   M   T7  2.6739 
7   1   G   M   T7  2.7505 
8   1   G   M   T7  2.6053 
9   1   S   S   T7  0.5736 
10  1   S   S   T7  0.5623 
11  1   S   S   T7  0.5590 
12  1   S   S   T7  0.5699 
13  1   S   M   T7  0.5723 
14  1   S   M   T7  0.5651 
15  1   S   M   T7  0.5741 
16  1   S   M   T7  0.5569 
1   2   G   S   T7  2.6702 
2   2   G   S   T7  2.5635 
3   2   G   S   T7  2.6946 
4   2   G   S   T7  2.7118 
5   2   G   M   T7  2.1614 
6   2   G   M   T7  2.1004 
7   2   G   M   T7  2.0792 
8   2   G   M   T7  2.3010 
9   2   S   S   T7  2.2175 
10  2   S   S   T7  2.3892 
11  2   S   S   T7  2.3284 
12  2   S   S   T7  2.3010 
13  2   S   M   T7  2.3222 
14  2   S   M   T7  2.1139 
15  2   S   M   T7  2.1461 
16  2   S   M   T7  2.0128 
1   3   G   S   T7  2.5328 
2   3   G   S   T7  2.5623 
3   3   G   S   T7  2.4624 
4   3   G   S   T7  2.6075 
5   3   G   M   T7  1.7709 
6   3   G   M   T7  1.5315 
7   3   G   M   T7  1.6902 
8   3   G   M   T7  1.6021 
9   3   S   S   T7  2.4786 
10  3   S   S   T7  2.3729 
11  3   S   S   T7  2.5809 
12  3   S   S   T7  2.6191 
13  3   S   M   T7  1.8388 
14  3   S   M   T7  2.0969 
15  3   S   M   T7  1.9590 
16  3   S   M   T7  2.1271 
1   1   G   S   T8  2.6180 
2   1   G   S   T8  2.6405 
3   1   G   S   T8  2.6385 
4   1   G   S   T8  2.6875 
5   1   G   M   T8  2.5092 
6   1   G   M   T8  2.6107 
7   1   G   M   T8  2.7185 
8   1   G   M   T8  2.6964 
9   1   S   S   T8  0.5585 
10  1   S   S   T8  0.5612 
11  1   S   S   T8  0.5609 
12  1   S   S   T8  0.5667 
13  1   S   M   T8  0.5452 
14  1   S   M   T8  0.5576 
15  1   S   M   T8  0.5704 
16  1   S   M   T8  0.5678 
1   2   G   S   T8  3.1355 
2   2   G   S   T8  3.2087 
3   2   G   S   T8  3.2117 
4   2   G   S   T8  3.3015 
5   2   G   M   T8  3.0580 
6   2   G   M   T8  3.2695 
7   2   G   M   T8  3.2269 
8   2   G   M   T8  2.9881 
9   2   S   S   T8  3.0569 
10  2   S   S   T8  3.0035 
11  2   S   S   T8  3.2405 
12  2   S   S   T8  3.0402 
13  2   S   M   T8  3.1294 
14  2   S   M   T8  3.1623 
15  2   S   M   T8  3.2095 
16  2   S   M   T8  3.0645 
1   3   G   S   T8  2.1430 
2   3   G   S   T8  2.2175 
3   3   G   S   T8  2.2788 
4   3   G   S   T8  2.3118 
5   3   G   M   T8  2.0607 
6   3   G   M   T8  2.3617 
7   3   G   M   T8  2.1430 
8   3   G   M   T8  2.4928 
9   3   S   S   T8  2.0043 
10  3   S   S   T8  2.1335 
11  3   S   S   T8  1.9085 
12  3   S   S   T8  2.0645 
13  3   S   M   T8  2.0645 
14  3   S   M   T8  2.3096 
15  3   S   M   T8  2.3784 
16  3   S   M   T8  2.3404 
1   1   G   S   T9  2.4265 
2   1   G   S   T9  2.4886 
3   1   G   S   T9  2.4393 
4   1   G   S   T9  2.4166 
5   1   G   M   T9  2.0569 
6   1   G   M   T9  2.1106 
7   1   G   M   T9  2.2833 
8   1   G   M   T9  2.1553 
9   1   S   S   T9  0.5349 
10  1   S   S   T9  0.5426 
11  1   S   S   T9  0.5365 
12  1   S   S   T9  0.5336 
13  1   S   M   T9  0.4853 
14  1   S   M   T9  0.4928 
15  1   S   M   T9  0.5163 
16  1   S   M   T9  0.4990 
1   2   G   S   T9  3.1258 
2   2   G   S   T9  3.2368 
3   2   G   S   T9  3.1498 
4   2   G   S   T9  3.3566 
5   2   G   M   T9  2.9956 
6   2   G   M   T9  3.0888 
7   2   G   M   T9  3.0265 
8   2   G   M   T9  2.9279 
9   2   S   S   T9  3.0892 
10  2   S   S   T9  3.2253 
11  2   S   S   T9  3.0531 
12  2   S   S   T9  3.0212 
13  2   S   M   T9  2.8176 
14  2   S   M   T9  3.0170 
15  2   S   M   T9  2.8899 
16  2   S   M   T9  2.8993 
1   3   G   S   T9  2.4928 
2   3   G   S   T9  2.3979 
3   3   G   S   T9  2.3617 
4   3   G   S   T9  2.2279 
5   3   G   M   T9  2.3324 
6   3   G   M   T9  2.5705 
7   3   G   M   T9  2.3892 
8   3   G   M   T9  2.7738 
9   3   S   S   T9  2.7839 
10  3   S   S   T9  2.8537 
11  3   S   S   T9  3.0527 
12  3   S   S   T9  2.8904 
13  3   S   M   T9  2.2355 
14  3   S   M   T9  2.3160 
15  3   S   M   T9  2.3404 
16  3   S   M   T9  3.1072 
1   1   G   S   T10 2.5145 
2   1   G   S   T10 2.4728 
3   1   G   S   T10 2.4487 
4   1   G   S   T10 2.4639 
5   1   G   M   T10 2.4757 
6   1   G   M   T10 2.5328 
7   1   G   M   T10 2.5441 
8   1   G   M   T10 2.3075 
9   1   S   S   T10 0.5459 
10  1   S   S   T10 0.5407 
11  1   S   S   T10 0.5377 
12  1   S   S   T10 0.5396 
13  1   S   M   T10 0.5410 
14  1   S   M   T10 0.5481 
15  1   S   M   T10 0.5495 
16  1   S   M   T10 0.5195 
1   2   G   S   T10 2.0414 
2   2   G   S   T10 2.0086 
3   2   G   S   T10 2.0792 
4   2   G   S   T10 2.1206 
5   2   G   M   T10 2.2788 
6   2   G   M   T10 2.2923 
7   2   G   M   T10 2.3856 
8   2   G   M   T10 2.1959 
9   2   S   S   T10 2.1959 
10  2   S   S   T10 2.1703 
11  2   S   S   T10 2.4232 
12  2   S   S   T10 2.2041 
13  2   S   M   T10 2.3139 
14  2   S   M   T10 2.2856 
15  2   S   M   T10 2.2227 
16  2   S   M   T10 2.1239 
1   3   G   S   T10 2.3711 
2   3   G   S   T10 2.5502 
3   3   G   S   T10 2.4133 
4   3   G   S   T10 2.6031 
5   3   G   M   T10 2.7694 
6   3   G   M   T10 2.8768 
7   3   G   M   T10 2.7803 
8   3   G   M   T10 2.7340 
9   3   S   S   T10 2.8331 
10  3   S   S   T10 2.9036 
11  3   S   S   T10 2.8976 
12  3   S   S   T10 2.7767 
13  3   S   M   T10 2.7435 
14  3   S   M   T10 2.8727 
15  3   S   M   T10 2.7860 
16  3   S   M   T10 2.8457 

@mpiktas:Just as you proposed,I didn't show my goal. My interest is to: (1)compare the response of a pest density to planting pattern and genotype;(2)is there any discrepancy among 3 successive years? I have tried linear mixed effect model using year as a random factor, to reduce the number of separate analyses and type I error using R. The concerned code is followed:

Data <- read.csv("aphids.csv", header=T)
Data$T <- as.numeric(Data$T) 
library(nlme)
aphids.lme <- lme(density ~ GENOTYPE*PATTERN+year+site , random=~T| year, 
      method=”ML”, na.action=na.omit, data=Data)
summary(aphids.lme)

is this right?

share|improve this question
3  
Lots of details are missing. What is the goal of your analysis? What have you tried? What precisely nlme was not able to do for you? From your questions it seems more that you need a statistics consultant. This site is more oriented to self-learning, so not putting any details (data is always welcome but in this particular case it is not enough) and waiting for complete answer will not give you any results. – mpiktas Sep 27 '11 at 8:13
1  
"I won't put up the details until I know someone knows what I'm talking about." That's rather offensive. – Karl Sep 27 '11 at 18:23
thank you for your suggestion.i will improve it soon – yangyang Sep 28 '11 at 1:28
Just as you proposed,I didn't show my goal. My interest is to: (1)compare the response of a pest density to planting pattern and genotype;(2)is there any discrepancy among 3 successive years? I have tried linear mixed effect model using year as a random factor, to reduce the number of separate analyses and type I error using R. The concerned code is followed: – yangyang Sep 28 '11 at 1:34

1 Answer

up vote 1 down vote accepted

This not a full answer, but too much for a comment.

  1. Are the treatments ordered? By converting them to a numeric value in line 2 of your code, you are assuming that they have values 1 through 10 in a meaningful way (eg. dose).

  2. The model you wrote has a fixed site effect, fixed year effect, and a linear treatment effect within each year. On the other hand, you don't have a fixed treatment effect. That is probably not what you intended. I would certainly make site a random effect, a if you care about the specific treatments (and they are not just random representatives of possible treatments), then make it a fixed effect.

  3. If you want to treat both site and year as random effect, you might find the lme4 package easier to use, because it handles crossed random effects much easier.

share|improve this answer
Aniko,thank you for your invaluable suggestion,I will try later. – yangyang Sep 29 '11 at 2:01
via @yangyang (please don't edit others' posts; with 50 rep you can post comment, otherwise edit your question directly): Just as you suggested,I meant to treat both site and year as random effect, but i am not whether is this code right. Data <- read.csv("aphids.csv", header=T) DataT<−as.numeric(DataT) library(lme4) aphids.lme <- lme(density ~ GENOTYPE*PATTERN, random=~T|year/site, method=”ML”, na.action=na.omit, data=Data) summary(aphids.lme) I am looking forward to your reply.Thank you for your invaluable suggestions. – chl Sep 29 '11 at 7:00
via@Aniko:Just as you suggested,I meant to treat both site and year as random effect, but i am not whether is this code right. Data <- read.csv("aphids.csv", header=T) DataT<−as.numeric(DataT) library(lme4) aphids.lme <- lme(density ~ GENOTYPE*PATTERN, random=~T|year/site, method=”ML”, na.action=na.omit, data=Data) summary(aphids.lme) I am looking forward to your reply.Thank you for your invaluable suggestions. – yangyang Oct 8 '11 at 6:40

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