Dear Crystallographers,
I've got the perplexing result of having systematically negative CCanom's for three different datasets from the same crystal. I cannot imagine how this could arise. At first I suspected it was just a noise artifact with some scaling-type shift, but I am back to perplexity. Negative (inverse) CC's mean if one element is high, the other is generally low and vice versa, so how does this work for anomalous pairs? Are the Imean's possibly skewed, maybe by twinning, making the anomalous differences systematically lopsided? But then the anomalous differences should be equivalently skewed, and the effect should be cancelled out. Or is it some more banal computational idiosyncrasy or even a bug?
Maybe the anomalous differences are expressed as signed values instead of absolute values for this calculation? I think that would yield this result, since anomalous differences of bijvoet mates should always be of opposite sign. Then I guess any dataset with anomalous signal would have a negative CC.
All the best,
Jacob
$TABLE: Correlations CC(1/2) within dataset, New:
$GRAPHS: CC(1/2) v resolution, max resolution 1.70, anom 0.00:0|0.346017x-0.473667|1:2,4,7,10,11:
: RMS correlation ratio :0|0.346017x0|0.965643:2,6:
: Rsplit :0|0.346017x0|0.356622:2,9:
$$
N 1/d^2 Dmid CCanom Nanom RCRanom CC1/2 NCC1/2 Rsplit CCfit CCanomfit $$ $$
1 0.0062 12.72 -0.251 415 0.774 0.996 538 0.033 1.000 -0.367
2 0.0185 7.34 -0.113 881 0.893 0.997 1032 0.030 1.000 -0.358
3 0.0309 5.69 -0.170 1111 0.843 0.993 1297 0.038 1.000 -0.349
4 0.0433 4.81 -0.401 1295 0.654 0.990 1518 0.041 0.999 -0.340
5 0.0556 4.24 -0.474 1492 0.598 0.991 1744 0.040 0.999 -0.332
6 0.0680 3.84 -0.365 1651 0.682 0.991 1889 0.040 0.999 -0.323
7 0.0803 3.53 -0.372 1786 0.677 0.990 2058 0.044 0.999 -0.314
8 0.0927 3.28 -0.356 1968 0.689 0.990 2216 0.044 0.998 -0.305
9 0.1050 3.09 -0.340 2088 0.702 0.981 2331 0.050 0.998 -0.296
10 0.1174 2.92 -0.314 2197 0.722 0.989 2481 0.049 0.997 -0.287
11 0.1298 2.78 -0.294 2380 0.738 0.989 2618 0.049 0.996 -0.278
12 0.1421 2.65 -0.299 2472 0.735 0.988 2715 0.053 0.995 -0.270
13 0.1545 2.54 -0.293 2581 0.739 0.986 2829 0.054 0.993 -0.261
14 0.1668 2.45 -0.282 2670 0.748 0.986 2945 0.056 0.991 -0.252
15 0.1792 2.36 -0.330 2766 0.710 0.985 3040 0.057 0.989 -0.243
16 0.1915 2.28 -0.356 2944 0.690 0.986 3133 0.059 0.985 -0.234
17 0.2039 2.21 -0.227 3047 0.794 0.983 3278 0.066 0.981 -0.225
18 0.2163 2.15 -0.273 3086 0.756 0.985 3342 0.066 0.975 -0.216
19 0.2286 2.09 -0.231 3181 0.790 0.979 3412 0.072 0.967 -0.207
20 0.2410 2.04 -0.203 3290 0.815 0.977 3535 0.079 0.958 -0.199
21 0.2533 1.99 -0.172 3384 0.843 0.973 3618 0.091 0.946 -0.190
22 0.2657 1.94 -0.198 3020 0.820 0.954 3667 0.116 0.930 -0.181
23 0.2780 1.90 -0.201 2470 0.817 0.929 3671 0.150 0.910 -0.172
24 0.2904 1.86 -0.140 1785 0.869 0.895 3504 0.188 0.886 -0.163
25 0.3028 1.82 -0.124 1076 0.883 0.844 3160 0.233 0.856 -0.154
26 0.3151 1.78 -0.062 697 0.940 0.811 2681 0.276 0.819 -0.145
27 0.3275 1.75 -0.048 253 0.953 0.736 1902 0.320 0.776 -0.136
28 0.3398 1.72 -0.035 65 0.966 0.727 1056 0.357 0.726 -0.128
$$
Overall: -0.329 56051 0.711 0.995 71210 0.054
CCanom Nanom RCRanom CC1/2 NCC1/2 Rsplit CCfit CCanomfit
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Jacob Pearson Keller, PhD
Looger Lab/HHMI Janelia Research Campus
19700 Helix Dr, Ashburn, VA 20147
email: [log in to unmask]
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