##-------------------------------------------## ## WARNING: ## ## Number of residues unspecified ## ##-------------------------------------------## Symmetry, cell and reflection file content summary Miller array info: /home/cqx/Desktop/150927/G4C2/ccp4i/G4C2-P3.mtz:IMEAN_New,SIGIMEAN_New Observation type: xray.intensity Type of data: double, size=9246 Type of sigmas: double, size=9246 Number of Miller indices: 9246 Anomalous flag: False Unit cell: (57.6999, 57.6999, 94.1305, 90, 90, 120) Space group: P 3 (No. 143) Systematic absences: 0 Centric reflections: 0 Resolution range: 34.2609 2.70044 Completeness in resolution range: 0.959826 Completeness with d_max=infinity: 0.959328 Wavelength: 0.9791 ################################################################################ # Basic statistics # ################################################################################ =================== Solvent content and Matthews coefficient ================== Number of residues unknown, assuming 50% solvent content Best guess : 331 residues in the ASU Caution: this estimate is based on the distribution of solvent content across structures in the PDB, but it does not take into account the resolution of the data (which is strongly correlated with solvent content) or the physical properties of the model (such as oligomerization state, et cetera). If you encounter problems with molecular replacement and/or refinement, you may need to consider the possibility that the ASU contents are different than expected. ======================== Data strength and completeness ======================= ----------Completeness at I/sigma cutoffs---------- The following table lists the completeness in various resolution ranges, after applying a I/sigI cut. Miller indices for which individual I/sigI values are larger than the value specified in the top row of the table, are retained, while other intensities are discarded. The resulting completeness profiles are an indication of the strength of the data. ---------------------------------------------------------------------------------------- | Completeness and data strength | |--------------------------------------------------------------------------------------| | Res. range | I/sigI>1 | I/sigI>2 | I/sigI>3 | I/sigI>5 | I/sigI>10 | I/sigI>15 | |--------------------------------------------------------------------------------------| | 34.26 - 6.64 | 91.0 | 91.0 | 90.2 | 85.0 | 64.9 | 20.4 | | 6.64 - 5.28 | 97.9 | 97.6 | 96.5 | 88.3 | 55.3 | 8.6 | | 5.28 - 4.61 | 98.3 | 97.1 | 95.8 | 90.1 | 55.2 | 5.3 | | 4.61 - 4.19 | 98.0 | 96.6 | 92.8 | 85.8 | 36.5 | 2.0 | | 4.19 - 3.89 | 94.6 | 90.5 | 84.9 | 71.9 | 24.2 | 0.0 | | 3.89 - 3.66 | 85.6 | 77.8 | 68.1 | 50.2 | 9.1 | 0.0 | | 3.66 - 3.48 | 95.7 | 91.6 | 84.0 | 60.1 | 11.0 | 0.0 | | 3.48 - 3.33 | 82.7 | 73.0 | 61.7 | 41.1 | 3.8 | 0.0 | | 3.33 - 3.20 | 84.0 | 68.2 | 57.0 | 36.4 | 2.5 | 0.0 | | 3.20 - 3.09 | 70.9 | 53.5 | 42.6 | 24.5 | 2.1 | 0.0 | | 3.09 - 2.99 | 49.6 | 31.7 | 18.0 | 5.0 | 0.0 | 0.0 | | 2.99 - 2.91 | 36.6 | 19.8 | 10.2 | 2.1 | 0.0 | 0.0 | | 2.91 - 2.83 | 44.0 | 20.0 | 7.2 | 0.8 | 0.0 | 0.0 | | 2.83 - 2.76 | 61.6 | 34.5 | 13.6 | 0.5 | 0.0 | 0.0 | ---------------------------------------------------------------------------------------- The completeness of data for which I/sig(I)>3.00, exceeds 85 % for resolution ranges lower than 4.19A. As we do not want to throw away too much data, the resolution for analyzing the intensity statistics will be limited to 3.50A. ----------Low resolution completeness analyses---------- The following table shows the completeness of the data to 5.0 A. Poor low-resolution completeness often leads to map distortions and other difficulties, and is typically caused by problems with the crystal orientation during data collection, overexposure of frames, interference with the beamstop, or omission of reflections by data-processing software. --------------------------------------------------------- | Resolution range | N(obs)/N(possible) | Completeness | --------------------------------------------------------- | 34.2617 - 10.6867 | [122/157] | 0.777 | | 10.6867 - 8.5254 | [130/147] | 0.884 | | 8.5254 - 7.4604 | [157/160] | 0.981 | | 7.4604 - 6.7841 | [150/151] | 0.993 | | 6.7841 - 6.3011 | [148/149] | 0.993 | | 6.3011 - 5.9316 | [143/144] | 0.993 | | 5.9316 - 5.6359 | [153/154] | 0.994 | | 5.6359 - 5.3915 | [156/160] | 0.975 | | 5.3915 - 5.1847 | [141/143] | 0.986 | | 5.1847 - 5.0063 | [156/156] | 1.000 | --------------------------------------------------------- ----------Completeness (log-binning)---------- The table below presents an alternative overview of data completeness, using the entire resolution range but on a logarithmic scale. This is more sensitive to missing low-resolution data (and is complementary to the separate table showing low-resolution completeness only). -------------------------------------------------- | Resolution | Reflections | Completeness | -------------------------------------------------- | 34.2609 - 11.1382 | 104/139 | 74.8% | | 11.0340 - 9.1945 | 96/108 | 88.9% | | 9.1497 - 7.5178 | 203/207 | 98.1% | | 7.4840 - 6.1894 | 343/346 | 99.1% | | 6.1738 - 5.0727 | 644/651 | 98.9% | | 5.0711 - 4.1666 | 1170/1177 | 99.4% | | 4.1641 - 3.4228 | 2057/2118 | 97.1% | | 3.4196 - 2.8127 | 3580/3795 | 94.3% | | 2.8115 - 2.7004 | 1049/1088 | 96.4% | -------------------------------------------------- ----------Analysis of resolution limits---------- Your data have been examined to determine the resolution limits of the data along the reciprocal space axes (a*, b*, and c*). These are expected to vary slightly depending on unit cell parameters and overall resolution, but should never be significantly different for complete data. (This is distinct from the amount of anisotropy present in the data, which changes the effective resolution but does not actually exclude reflections.) overall d_min = 2.700 d_min along a* = 2.776 d_min along b* = 2.776 d_min along c* = 2.769 max. difference between axes = 0.008 Resolution limits are within expected tolerances. ================================== Input data ================================= ----------Summary---------- File name: G4C2-P3.mtz Data labels: IMEAN_New,SIGIMEAN_New Space group: P 3 Unit cell: 57.6999, 57.6999, 94.1305, 90, 90, 120 Data type: xray.intensity Resolution: 34.2609 - 2.70044 Anomalous: False Number of reflections: 9246 Completeness: 95.93% Completeness should be used to determine if there is sufficient data for refinement and/or model-building. A value greater than 90% is generally desired, while a value less than 75% is considered poor. Values in between will provide less than optimal results. ===================== Absolute scaling and Wilson analysis ==================== ----------Maximum likelihood isotropic Wilson scaling---------- ML estimate of overall B value: 67.02 A**(-2) Estimated -log of scale factor: -2.71 The overall B value ("Wilson B-factor", derived from the Wilson plot) gives an isotropic approximation for the falloff of intensity as a function of resolution. Note that this approximation may be misleading for anisotropic data (where the crystal is poorly ordered along an axis). The Wilson B is strongly correlated with refined atomic B-factors but these may differ by a significant amount, especially if anisotropy is present. ----------Maximum likelihood anisotropic Wilson scaling---------- ML estimate of overall B_cart value: 79.21, -0.00, 0.00 79.21, 0.00 40.42 Equivalent representation as U_cif: 1.00, 0.50, -0.00 1.00, 0.00 0.51 Eigen analyses of B-cart: ------------------------------------------------- | Eigenvector | Value | Vector | ------------------------------------------------- | 1 | 79.206 | ( 0.89, -0.46, -0.00) | | 2 | 79.206 | ( 0.46, 0.89, 0.00) | | 3 | 40.419 | (-0.00, -0.00, 1.00) | ------------------------------------------------- ML estimate of -log of scale factor: -2.79 ----------Anisotropy analyses---------- For the resolution shell spanning between 3.02 - 2.70 Angstrom, the mean I/sigI is equal to 1.78. 14.8 % of these intensities have an I/sigI > 3. When sorting these intensities by their anisotropic correction factor and analysing the I/sigI behavior for this ordered list, we can gauge the presence of 'anisotropy induced noise amplification' in reciprocal space. The quarter of Intensities *least* affected by the anisotropy correction show : 1.62e+00 Fraction of I/sigI > 3 : 1.17e-01 ( Z = 1.94 ) The quarter of Intensities *most* affected by the anisotropy correction show : 2.24e+00 Fraction of I/sigI > 3 : 2.40e-01 ( Z = 5.83 ) Z-scores are computed on the basis of a Bernoulli model assuming independence of weak reflections with respect to anisotropy. ----------Wilson plot---------- The Wilson plot shows the falloff in intensity as a function in resolution; this is used to calculate the overall B-factor ("Wilson B-factor") for the data shown above. The expected plot is calculated based on analysis of macromolecule structures in the PDB, and the distinctive appearance is due to the non-random arrangement of atoms in the crystal. Some variation is natural, but major deviations from the expected plot may indicate pathological data (including ice rings, detector problems, or processing errors). ----------Mean intensity analyses---------- Inspired by: Morris et al. (2004). J. Synch. Rad.11, 56-59. The following resolution shells are worrisome: ----------------------------------------------------------------- | Mean intensity by shell (outliers) | |---------------------------------------------------------------| | d_spacing | z_score | completeness | / | |---------------------------------------------------------------| | 6.738 | 7.09 | 0.99 | 2.217 | | 4.471 | 4.95 | 0.99 | 0.723 | | 4.302 | 9.78 | 0.99 | 0.572 | | 4.151 | 10.64 | 0.99 | 0.559 | | 4.015 | 6.54 | 0.96 | 0.694 | | 3.892 | 10.57 | 0.94 | 0.579 | | 3.779 | 4.53 | 0.87 | 0.771 | | 3.071 | 9.45 | 0.76 | 0.608 | | 3.015 | 13.03 | 0.64 | 0.514 | | 2.961 | 10.79 | 0.60 | 0.570 | | 2.911 | 13.38 | 0.65 | 0.517 | | 2.817 | 4.59 | 0.80 | 1.341 | | 2.773 | 6.27 | 0.84 | 1.554 | | 2.732 | 7.43 | 0.81 | 1.655 | ----------------------------------------------------------------- Possible reasons for the presence of the reported unexpected low or elevated mean intensity in a given resolution bin are : - missing overloaded or weak reflections - suboptimal data processing - satellite (ice) crystals - NCS - translational pseudo symmetry (detected elsewhere) - outliers (detected elsewhere) - ice rings (detected elsewhere) - other problems Note that the presence of abnormalities in a certain region of reciprocal space might confuse the data validation algorithm throughout a large region of reciprocal space, even though the data are acceptable in those areas. ----------Possible outliers---------- Inspired by: Read, Acta Cryst. (1999). D55, 1759-1764 Acentric reflections: ----------------------------------------------------------------------------------------------------- | Acentric reflections | |---------------------------------------------------------------------------------------------------| | d_spacing | H K L | |E| | p(wilson) | p(extreme) | |---------------------------------------------------------------------------------------------------| | 3.167 | 2, 2, -29 | 3.59 | 2.55e-06 | 2.09e-02 | ----------------------------------------------------------------------------------------------------- p(wilson) : 1-(1-exp[-|E|^2]) p(extreme) : 1-(1-exp[-|E|^2])^(n_acentrics) p(wilson) is the probability that an E-value of the specified value would be observed if it were selected at random the given data set. p(extreme) is the probability that the largest |E| value is larger or equal than the observed largest |E| value. Both measures can be used for outlier detection. p(extreme) takes into account the size of the dataset. Centric reflections: None ----------Ice ring related problems---------- The following statistics were obtained from ice-ring insensitive resolution ranges: mean bin z_score : 5.17 ( rms deviation : 3.94 ) mean bin completeness : 0.88 ( rms deviation : 0.12 ) The following table shows the Wilson plot Z-scores and completeness for observed data in ice-ring sensitive areas. The expected relative intensity is the theoretical intensity of crystalline ice at the given resolution. Large z-scores and high completeness in these resolution ranges might be a reason to re-assess your data processsing if ice rings were present. ------------------------------------------------------------- | d_spacing | Expected rel. I | Data Z-score | Completeness | ------------------------------------------------------------- | 3.897 | 1.000 | 10.57 | 0.94 | | 3.669 | 0.750 | 0.18 | 0.97 | | 3.441 | 0.530 | 1.59 | 0.92 | ------------------------------------------------------------- Abnormalities in mean intensity or completeness at resolution ranges with a relative ice ring intensity lower than 0.10 will be ignored. At 3.90 A the z-score is more than 4.00 times the standard deviation of all z-scores, while at the same time, the completeness does not go down. As there was only 1 ice-ring related warning, it is not clear whether or not ice ring related features are really present. ################################################################################ # Twinning and symmetry analyses # ################################################################################ ============================= Systematic absences ============================= ----------Table of systematic absence rules---------- The following table gives information about systematic absences allowed for the specified intensity point group. For each operator, the reflections are split in three classes: Systematic absence: Reflections that are absent for this operator. Non absence : Reflections of the same type (i.e. (0,0,l)) as above, but they should be present. Other reflections : All other reflections. For each class, the is reported, as well as the number of violations. A violation is a reflection that is absent when it is expected to be present for a particular space group, or present when it is expected to be absent. The criteria are: Systematic absence violation: I/sigI > 3.0 Non absence violation : I/sigI < 3.0 Other relections violation : I/sigI < 3.0 Operators with low associated violations for *both* systematically absent and non absent reflections, are likely to be true screw axis or glide planes. Both the number of violations and their percentages are given. The number of violations within the 'other reflections' class, can be used as a comparison for the number of violations in the non-absent class. --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | Operator | # expected systematic absences | (violations) | # expected non absences | (violations) | # other reflections | (violations) | Score | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | 3_0 (c) | 0 | 0.00 (0, 0.0%) | 0 | 0.00 (0, 0.0%) | 4147 | 9.02 (282, 6.8%) | 0.00e+00 | | 3_1 (c) | 0 | 0.00 (0, 0.0%) | 0 | 0.00 (0, 0.0%) | 4147 | 9.02 (282, 6.8%) | 0.00e+00 | | 3_2 (c) | 0 | 0.00 (0, 0.0%) | 0 | 0.00 (0, 0.0%) | 4147 | 9.02 (282, 6.8%) | 0.00e+00 | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ----------Space group identification---------- Analyses of the absences table indicates a number of likely space group candidates, which are listed below. For each space group, the number of systematic absence violations are listed under the '+++' column. The number of non-absence violations (weak reflections) are listed under '---'. The last column is a likelihood based score for the particular space group. Note that enantiomorphic spacegroups will have equal scores. Also, if absences were removed while processing the data, they will be regarded as missing information, rather then as enforcing that absence in the space group choices. ------------------------------------------------------------------------------------ | space group | # absent | _absent | _absent | +++ | --- | score | ------------------------------------------------------------------------------------ | P 3 | 0 | 0.00 | 0.00 | 0 | 0 | 0.000e+00 | | P 31 | 0 | 0.00 | 0.00 | 0 | 0 | 0.000e+00 | | P 32 | 0 | 0.00 | 0.00 | 0 | 0 | 0.000e+00 | ------------------------------------------------------------------------------------ ----------List of individual systematic absences---------- Note: this analysis uses the original input data rather than the filtered data used for twinning detection; therefore, the results shown here may include more reflections than shown above. P 3 (input space group): no systematic absences possible P 31: no absences found P 32: no absences found =============== Diagnostic tests for twinning and pseudosymmetry ============== Using data between 10.00 to 3.50 Angstrom. ----------Patterson analyses---------- Largest Patterson peak with length larger than 15 Angstrom: Frac. coord. : 0.000 0.500 0.000 Distance to origin : 28.850 Height relative to origin : 29.943 % p_value(height) : 1.422e-03 Explanation The p-value, the probability that a peak of the specified height or larger is found in a Patterson function of a macromolecule that does not have any translational pseudo-symmetry, is equal to 1.422e-03. p_values smaller than 0.05 might indicate weak translational pseudo symmetry, or the self vector of a large anomalous scatterer such as Hg, whereas values smaller than 1e-3 are a very strong indication for the presence of translational pseudo symmetry. Translational pseudo-symmetry is very likely present in these data. Be aware that this will change the intensity statistics and may impact subsequent analyses, and in practice may lead to higher R-factors in refinement. ----------Wilson ratio and moments---------- Acentric reflections: /^2 :2.440 (untwinned: 2.000; perfect twin 1.500) ^2/ :0.741 (untwinned: 0.785; perfect twin 0.885) <|E^2 - 1|> :0.834 (untwinned: 0.736; perfect twin 0.541) ----------NZ test for twinning and TNCS---------- The NZ test is diagnostic for both twinning and translational NCS. Note however that if both are present, the effects may cancel each other out, therefore the results of the Patterson analysis and L-test also need to be considered. Maximum deviation acentric : 0.075 Maximum deviation centric : 0.683 _acentric : +0.048 _centric : -0.467 ----------L test for acentric data---------- Using difference vectors (dh,dk,dl) of the form: (2hp, 2kp, 2lp) where hp, kp, and lp are random signed integers such that 2 <= |dh| + |dk| + |dl| <= 8 Mean |L| :0.440 (untwinned: 0.500; perfect twin: 0.375) Mean L^2 :0.271 (untwinned: 0.333; perfect twin: 0.200) The distribution of |L| values indicates a twin fraction of 0.00. Note that this estimate is not as reliable as obtained via a Britton plot or H-test if twin laws are available. Reference: J. Padilla & T. O. Yeates. A statistic for local intensity differences: robustness to anisotropy and pseudo-centering and utility for detecting twinning. Acta Crystallogr. D59, 1124-30, 2003. ================================== Twin laws ================================== ----------Twin law identification---------- Possible twin laws: -------------------------------------------------------------------------------- | Type | Axis | R metric (%) | delta (le Page) | delta (Lebedev) | Twin law | -------------------------------------------------------------------------------- | M | 2-fold | 0.000 | 0.000 | 0.000 | -h,-k,l | | M | 2-fold | 0.000 | 0.000 | 0.000 | h,-h-k,-l | | M | 2-fold | 0.000 | 0.000 | 0.000 | -k,-h,-l | -------------------------------------------------------------------------------- 3 merohedral twin operators found 0 pseudo-merohedral twin operators found In total, 3 twin operators were found Please note that the possibility of twin laws only means that the lattice symmetry permits twinning; it does not mean that the data are actually twinned. You should only treat the data as twinned if the intensity statistics are abnormal. ----------Twin law-specific tests---------- The following tests analyze the input data with each of the possible twin laws applied. If twinning is present, the most appropriate twin law will usually have a low R_abs_twin value and a consistent estimate of the twin fraction (significantly above 0) from each test. The results are also compiled in the summary section. WARNING: please remember that the possibility of twin laws, and the results of the specific tests, does not guarantee that twinning is actually present in the data. Only the presence of abnormal intensity statistics (as judged by the Wilson moments, NZ-test, and L-test) is diagnostic for twinning. ----------Analysis of twin law -h,-k,l---------- H-test on acentric data Only 50.0 % of the strongest twin pairs were used. mean |H| : 0.047 (0.50: untwinned; 0.0: 50% twinned) mean H^2 : 0.005 (0.33: untwinned; 0.0: 50% twinned) Estimation of twin fraction via mean |H|: 0.453 Estimation of twin fraction via cum. dist. of H: 0.458 Britton analyses Extrapolation performed on 0.46 < alpha < 0.495 Estimated twin fraction: 0.429 Correlation: 0.9909 R vs R statistics R_abs_twin = <|I1-I2|>/<|I1+I2|> (Lebedev, Vagin, Murshudov. Acta Cryst. (2006). D62, 83-95) R_abs_twin observed data : 0.051 R_sq_twin = <(I1-I2)^2>/<(I1+I2)^2> R_sq_twin observed data : 0.004 No calculated data available. R_twin for calculated data not determined. ----------Analysis of twin law h,-h-k,-l---------- H-test on acentric data Only 50.0 % of the strongest twin pairs were used. mean |H| : 0.043 (0.50: untwinned; 0.0: 50% twinned) mean H^2 : 0.006 (0.33: untwinned; 0.0: 50% twinned) Estimation of twin fraction via mean |H|: 0.457 Estimation of twin fraction via cum. dist. of H: 0.468 Britton analyses Extrapolation performed on 0.47 < alpha < 0.495 Estimated twin fraction: 0.441 Correlation: 0.9940 R vs R statistics R_abs_twin = <|I1-I2|>/<|I1+I2|> (Lebedev, Vagin, Murshudov. Acta Cryst. (2006). D62, 83-95) R_abs_twin observed data : 0.049 R_sq_twin = <(I1-I2)^2>/<(I1+I2)^2> R_sq_twin observed data : 0.003 No calculated data available. R_twin for calculated data not determined. ----------Analysis of twin law -k,-h,-l---------- H-test on acentric data Only 50.0 % of the strongest twin pairs were used. mean |H| : 0.045 (0.50: untwinned; 0.0: 50% twinned) mean H^2 : 0.005 (0.33: untwinned; 0.0: 50% twinned) Estimation of twin fraction via mean |H|: 0.455 Estimation of twin fraction via cum. dist. of H: 0.458 Britton analyses Extrapolation performed on 0.47 < alpha < 0.495 Estimated twin fraction: 0.439 Correlation: 0.9953 R vs R statistics R_abs_twin = <|I1-I2|>/<|I1+I2|> (Lebedev, Vagin, Murshudov. Acta Cryst. (2006). D62, 83-95) R_abs_twin observed data : 0.051 R_sq_twin = <(I1-I2)^2>/<(I1+I2)^2> R_sq_twin observed data : 0.004 No calculated data available. R_twin for calculated data not determined. ======================= Exploring higher metric symmetry ====================== The point group of data as dictated by the space group is P 3 The point group in the niggli setting is P 3 The point group of the lattice is P 6 2 2 A summary of R values for various possible point groups follow. ---------------------------------------------------------------------------------------------- | Point group | mean R_used | max R_used | mean R_unused | min R_unused | BIC | choice | ---------------------------------------------------------------------------------------------- | P 3 | None | None | 0.050 | 0.049 | 1.727e+04 | | | P 6 2 2 | 0.050 | 0.051 | None | None | 6.172e+03 | | | P 3 2 1 | 0.049 | 0.049 | 0.051 | 0.051 | 1.025e+04 | | | P 6 | 0.051 | 0.051 | 0.050 | 0.049 | 9.554e+03 | | | P 3 1 2 | 0.051 | 0.051 | 0.050 | 0.049 | 9.904e+03 | | ---------------------------------------------------------------------------------------------- R_used: mean and maximum R value for symmetry operators *used* in this point group R_unused: mean and minimum R value for symmetry operators *not used* in this point group An automated point group suggestion is made on the basis of the BIC (Bayesian information criterion). The likely point group of the data is: P 6 2 2 Possible space groups in this point group are: Unit cell: (57.6999, 57.6999, 94.1305, 90, 90, 120) Space group: P 6 2 2 (No. 177) Unit cell: (57.6999, 57.6999, 94.1305, 90, 90, 120) Space group: P 61 2 2 (No. 178) Unit cell: (57.6999, 57.6999, 94.1305, 90, 90, 120) Space group: P 65 2 2 (No. 179) Unit cell: (57.6999, 57.6999, 94.1305, 90, 90, 120) Space group: P 62 2 2 (No. 180) Unit cell: (57.6999, 57.6999, 94.1305, 90, 90, 120) Space group: P 64 2 2 (No. 181) Unit cell: (57.6999, 57.6999, 94.1305, 90, 90, 120) Space group: P 63 2 2 (No. 182) Note that this analysis does not take into account the effects of twinning. If the data are (almost) perfectly twinned, the symmetry will appear to be higher than it actually is. ================== Twinning and intensity statistics summary ================== ----------Final verdict---------- The analyses of the Patterson function reveals a significant off-origin peak that is 29.94 % of the origin peak, indicating pseudo-translational symmetry. The chance of finding a peak of this or larger height by random in a structure without pseudo-translational symmetry is equal to 1.4219e-03. The detected translational NCS is most likely also responsible for the elevated intensity ratio. See the relevant section of the logfile for more details. The results of the L-test indicate that the intensity statistics are significantly different than is expected from good to reasonable, untwinned data. As there are twin laws possible given the crystal symmetry, twinning could be the reason for the departure of the intensity statistics from normality. It might be worthwhile carrying out refinement with a twin specific target function. Please note however that R-factors from twinned refinement cannot be directly compared to R-factors without twinning, as they will always be lower when a twin law is used. You should also use caution when interpreting the maps from refinement, as they will have significantly more model bias. Note that the symmetry of the intensities suggest that the assumed space group is too low. As twinning is however suspected, it is not immediately clear if this is the case. Careful reprocessing and (twin)refinement for all cases might resolve this question. ----------Statistics independent of twin laws---------- /^2 : 2.440 (untwinned: 2.0, perfect twin: 1.5) ^2/ : 0.741 (untwinned: 0.785, perfect twin: 0.885) <|E^2-1|> : 0.834 (untwinned: 0.736, perfect twin: 0.541) <|L|> : 0.440 (untwinned: 0.500; perfect twin: 0.375) : 0.271 (untwinned: 0.333; perfect twin: 0.200) Multivariate Z score L-test: 6.338 The multivariate Z score is a quality measure of the given spread in intensities. Good to reasonable data are expected to have a Z score lower than 3.5. Large values can indicate twinning, but small values do not necessarily exclude it. Note that the expected values for perfect twinning are for merohedrally twinned structures, and deviations from untwinned will be larger for perfect higher-order twinning. ----------Statistics depending on twin laws---------- ------------------------------------------------------------------ | Operator | type | R obs. | Britton alpha | H alpha | ML alpha | ------------------------------------------------------------------ | -h,-k,l | M | 0.051 | 0.429 | 0.458 | 0.478 | | h,-h-k,-l | M | 0.049 | 0.441 | 0.468 | 0.478 | | -k,-h,-l | M | 0.051 | 0.439 | 0.458 | 0.478 | ------------------------------------------------------------------