Stomach Adenocarcinoma: Correlation between copy number variations of arm-level result and selected clinical features
(primary solid tumor cohort)
Maintained by TCGA GDAC Team (Broad Institute/MD Anderson Cancer Center/Harvard Medical School)
Overview
Introduction

This pipeline computes the correlation between significant arm-level copy number variations (cnvs) and selected clinical features.

Summary

Testing the association between copy number variation 74 arm-level results and 9 clinical features across 161 patients, 6 significant findings detected with Q value < 0.25.

  • 20p gain cnv correlated to 'GENDER'.

  • 20q gain cnv correlated to 'GENDER'.

  • 1p loss cnv correlated to 'PATHOLOGICSPREAD(M)' and 'TUMOR.STAGE'.

  • 12p loss cnv correlated to 'PATHOLOGY.N' and 'TUMOR.STAGE'.

Results
Overview of the results

Table 1.  Get Full Table Overview of the association between significant copy number variation of 74 arm-level results and 9 clinical features. Shown in the table are P values (Q values). Thresholded by Q value < 0.25, 6 significant findings detected.

Clinical
Features
Time
to
Death
AGE GENDER HISTOLOGICAL
TYPE
PATHOLOGY
T
PATHOLOGY
N
PATHOLOGICSPREAD(M) TUMOR
STAGE
RADIATIONS
RADIATION
REGIMENINDICATION
nCNV (%) nWild-Type logrank test t-test Fisher's exact test Chi-square test Fisher's exact test Fisher's exact test Fisher's exact test Fisher's exact test Fisher's exact test
1p loss 6 (4%) 155 0.00489
(1.00)
0.688
(1.00)
0.222
(1.00)
0.885
(1.00)
0.335
(1.00)
0.313
(1.00)
0.000111
(0.0726)
0.000345
(0.224)
1
(1.00)
12p loss 11 (7%) 150 0.174
(1.00)
0.705
(1.00)
0.527
(1.00)
0.361
(1.00)
0.0564
(1.00)
0.000243
(0.158)
0.46
(1.00)
0.000228
(0.148)
0.301
(1.00)
20p gain 61 (38%) 100 0.0693
(1.00)
0.207
(1.00)
0.000128
(0.0831)
0.685
(1.00)
0.0515
(1.00)
0.691
(1.00)
0.149
(1.00)
0.19
(1.00)
0.651
(1.00)
20q gain 75 (47%) 86 0.0524
(1.00)
0.134
(1.00)
0.00037
(0.24)
0.399
(1.00)
0.000745
(0.481)
0.264
(1.00)
0.0532
(1.00)
0.189
(1.00)
0.665
(1.00)
1p gain 6 (4%) 155 0.212
(1.00)
0.403
(1.00)
0.712
(1.00)
1
(1.00)
0.809
(1.00)
0.45
(1.00)
1
(1.00)
1
(1.00)
1q gain 19 (12%) 142 0.77
(1.00)
0.521
(1.00)
0.22
(1.00)
0.3
(1.00)
0.422
(1.00)
0.214
(1.00)
0.384
(1.00)
0.335
(1.00)
0.106
(1.00)
2p gain 10 (6%) 151 0.692
(1.00)
0.292
(1.00)
0.741
(1.00)
0.586
(1.00)
0.272
(1.00)
0.291
(1.00)
1
(1.00)
0.0578
(1.00)
1
(1.00)
2q gain 11 (7%) 150 0.406
(1.00)
0.588
(1.00)
0.527
(1.00)
0.605
(1.00)
0.532
(1.00)
0.291
(1.00)
0.831
(1.00)
0.213
(1.00)
1
(1.00)
3p gain 4 (2%) 157 0.543
(1.00)
0.648
(1.00)
0.862
(1.00)
0.856
(1.00)
0.394
(1.00)
1
(1.00)
0.529
(1.00)
1
(1.00)
3q gain 13 (8%) 148 0.377
(1.00)
0.0273
(1.00)
0.0157
(1.00)
0.484
(1.00)
1
(1.00)
0.767
(1.00)
0.503
(1.00)
1
(1.00)
1
(1.00)
4p gain 3 (2%) 158 0.159
(1.00)
0.273
(1.00)
0.0522
(1.00)
0.729
(1.00)
1
(1.00)
0.284
(1.00)
1
(1.00)
5p gain 26 (16%) 135 0.975
(1.00)
0.763
(1.00)
0.19
(1.00)
0.494
(1.00)
0.935
(1.00)
0.681
(1.00)
0.253
(1.00)
0.108
(1.00)
0.184
(1.00)
5q gain 6 (4%) 155 0.137
(1.00)
0.792
(1.00)
0.403
(1.00)
0.0419
(1.00)
0.901
(1.00)
0.877
(1.00)
1
(1.00)
0.594
(1.00)
1
(1.00)
6p gain 11 (7%) 150 0.788
(1.00)
0.838
(1.00)
0.758
(1.00)
0.799
(1.00)
0.243
(1.00)
0.727
(1.00)
1
(1.00)
0.453
(1.00)
1
(1.00)
6q gain 10 (6%) 151 0.35
(1.00)
0.891
(1.00)
1
(1.00)
0.78
(1.00)
0.354
(1.00)
0.746
(1.00)
0.661
(1.00)
0.719
(1.00)
1
(1.00)
7p gain 49 (30%) 112 0.524
(1.00)
0.0136
(1.00)
0.117
(1.00)
0.319
(1.00)
0.464
(1.00)
0.556
(1.00)
0.673
(1.00)
0.181
(1.00)
0.641
(1.00)
7q gain 44 (27%) 117 0.735
(1.00)
0.00432
(1.00)
0.37
(1.00)
0.446
(1.00)
0.204
(1.00)
0.643
(1.00)
0.255
(1.00)
0.157
(1.00)
1
(1.00)
8p gain 50 (31%) 111 0.599
(1.00)
0.0443
(1.00)
0.386
(1.00)
0.487
(1.00)
0.0857
(1.00)
0.585
(1.00)
0.0932
(1.00)
0.59
(1.00)
0.174
(1.00)
8q gain 68 (42%) 93 0.302
(1.00)
0.03
(1.00)
0.421
(1.00)
0.635
(1.00)
0.0122
(1.00)
0.191
(1.00)
0.153
(1.00)
0.258
(1.00)
0.651
(1.00)
9p gain 11 (7%) 150 0.844
(1.00)
0.319
(1.00)
0.353
(1.00)
0.708
(1.00)
0.051
(1.00)
0.127
(1.00)
1
(1.00)
0.00597
(1.00)
0.301
(1.00)
9q gain 15 (9%) 146 0.856
(1.00)
0.188
(1.00)
0.595
(1.00)
0.942
(1.00)
0.144
(1.00)
0.134
(1.00)
0.871
(1.00)
0.161
(1.00)
0.391
(1.00)
10p gain 23 (14%) 138 0.976
(1.00)
0.34
(1.00)
0.362
(1.00)
0.315
(1.00)
0.537
(1.00)
0.752
(1.00)
0.41
(1.00)
0.071
(1.00)
1
(1.00)
10q gain 10 (6%) 151 0.634
(1.00)
0.987
(1.00)
0.741
(1.00)
0.646
(1.00)
0.894
(1.00)
0.746
(1.00)
0.812
(1.00)
0.696
(1.00)
1
(1.00)
11p gain 4 (2%) 157 0.572
(1.00)
0.648
(1.00)
0.676
(1.00)
0.385
(1.00)
0.183
(1.00)
1
(1.00)
0.335
(1.00)
1
(1.00)
11q gain 8 (5%) 153 0.24
(1.00)
0.77
(1.00)
1
(1.00)
0.802
(1.00)
0.864
(1.00)
0.743
(1.00)
0.774
(1.00)
0.709
(1.00)
1
(1.00)
12p gain 15 (9%) 146 0.726
(1.00)
0.273
(1.00)
0.105
(1.00)
0.998
(1.00)
0.374
(1.00)
0.655
(1.00)
0.163
(1.00)
0.676
(1.00)
1
(1.00)
12q gain 10 (6%) 151 0.669
(1.00)
0.0563
(1.00)
0.741
(1.00)
0.309
(1.00)
0.894
(1.00)
0.152
(1.00)
0.812
(1.00)
0.61
(1.00)
0.277
(1.00)
13q gain 30 (19%) 131 0.331
(1.00)
0.731
(1.00)
0.222
(1.00)
0.501
(1.00)
0.676
(1.00)
0.474
(1.00)
0.617
(1.00)
0.69
(1.00)
1
(1.00)
15q gain 7 (4%) 154 0.178
(1.00)
0.414
(1.00)
0.243
(1.00)
0.364
(1.00)
0.569
(1.00)
0.0674
(1.00)
1
(1.00)
0.439
(1.00)
1
(1.00)
16p gain 12 (7%) 149 0.575
(1.00)
0.614
(1.00)
0.763
(1.00)
0.61
(1.00)
0.341
(1.00)
0.0675
(1.00)
0.118
(1.00)
0.00787
(1.00)
0.325
(1.00)
16q gain 8 (5%) 153 0.671
(1.00)
0.864
(1.00)
1
(1.00)
0.862
(1.00)
0.0719
(1.00)
0.354
(1.00)
0.195
(1.00)
0.0167
(1.00)
1
(1.00)
17p gain 6 (4%) 155 0.16
(1.00)
0.55
(1.00)
1
(1.00)
0.805
(1.00)
0.812
(1.00)
0.0818
(1.00)
0.0268
(1.00)
0.142
(1.00)
1
(1.00)
17q gain 9 (6%) 152 0.174
(1.00)
0.666
(1.00)
0.741
(1.00)
0.879
(1.00)
0.829
(1.00)
0.118
(1.00)
0.0225
(1.00)
0.197
(1.00)
1
(1.00)
18p gain 13 (8%) 148 0.61
(1.00)
0.564
(1.00)
1
(1.00)
0.813
(1.00)
1
(1.00)
0.0956
(1.00)
0.614
(1.00)
0.632
(1.00)
0.347
(1.00)
18q gain 7 (4%) 154 0.598
(1.00)
0.619
(1.00)
0.441
(1.00)
0.313
(1.00)
0.563
(1.00)
0.777
(1.00)
0.146
(1.00)
0.89
(1.00)
1
(1.00)
19p gain 10 (6%) 151 0.965
(1.00)
0.429
(1.00)
0.0155
(1.00)
0.536
(1.00)
0.806
(1.00)
0.0475
(1.00)
0.043
(1.00)
0.0455
(1.00)
1
(1.00)
19q gain 17 (11%) 144 0.309
(1.00)
0.214
(1.00)
0.121
(1.00)
0.509
(1.00)
0.404
(1.00)
0.105
(1.00)
0.219
(1.00)
0.0247
(1.00)
0.432
(1.00)
22q gain 3 (2%) 158 0.765
(1.00)
0.266
(1.00)
1
(1.00)
0.927
(1.00)
0.817
(1.00)
0.382
(1.00)
1
(1.00)
0.284
(1.00)
1
(1.00)
2p loss 3 (2%) 158 0.566
(1.00)
0.817
(1.00)
0.437
(1.00)
0.223
(1.00)
0.336
(1.00)
0.0909
(1.00)
2q loss 4 (2%) 157 0.867
(1.00)
1
(1.00)
0.308
(1.00)
0.614
(1.00)
0.0917
(1.00)
0.149
(1.00)
0.16
(1.00)
0.12
(1.00)
3p loss 10 (6%) 151 0.633
(1.00)
0.561
(1.00)
1
(1.00)
0.865
(1.00)
0.729
(1.00)
0.746
(1.00)
1
(1.00)
0.677
(1.00)
1
(1.00)
3q loss 6 (4%) 155 0.727
(1.00)
0.639
(1.00)
0.403
(1.00)
0.852
(1.00)
1
(1.00)
0.877
(1.00)
1
(1.00)
0.734
(1.00)
1
(1.00)
4p loss 24 (15%) 137 0.704
(1.00)
0.129
(1.00)
0.824
(1.00)
0.0812
(1.00)
0.0367
(1.00)
1
(1.00)
0.565
(1.00)
0.0682
(1.00)
0.161
(1.00)
4q loss 20 (12%) 141 0.748
(1.00)
0.338
(1.00)
0.466
(1.00)
0.0279
(1.00)
0.0243
(1.00)
0.837
(1.00)
1
(1.00)
0.301
(1.00)
0.117
(1.00)
5p loss 7 (4%) 154 0.415
(1.00)
0.607
(1.00)
1
(1.00)
0.022
(1.00)
0.614
(1.00)
0.375
(1.00)
1
(1.00)
0.397
(1.00)
1
(1.00)
5q loss 15 (9%) 146 0.12
(1.00)
0.5
(1.00)
0.286
(1.00)
0.000403
(0.26)
0.0522
(1.00)
0.903
(1.00)
0.242
(1.00)
0.181
(1.00)
0.391
(1.00)
6p loss 8 (5%) 153 0.958
(1.00)
0.0474
(1.00)
0.715
(1.00)
0.0136
(1.00)
0.134
(1.00)
0.166
(1.00)
0.578
(1.00)
0.229
(1.00)
1
(1.00)
6q loss 12 (7%) 149 0.611
(1.00)
0.218
(1.00)
0.763
(1.00)
0.191
(1.00)
0.202
(1.00)
0.428
(1.00)
0.85
(1.00)
0.0368
(1.00)
1
(1.00)
7p loss 3 (2%) 158 0.213
(1.00)
0.192
(1.00)
0.273
(1.00)
0.721
(1.00)
0.0916
(1.00)
0.0806
(1.00)
1
(1.00)
0.456
(1.00)
1
(1.00)
7q loss 5 (3%) 156 0.208
(1.00)
0.14
(1.00)
0.0819
(1.00)
0.454
(1.00)
0.379
(1.00)
0.477
(1.00)
1
(1.00)
0.929
(1.00)
1
(1.00)
8p loss 10 (6%) 151 0.27
(1.00)
0.439
(1.00)
0.741
(1.00)
0.0385
(1.00)
0.592
(1.00)
0.4
(1.00)
0.812
(1.00)
0.625
(1.00)
1
(1.00)
8q loss 3 (2%) 158 0.607
(1.00)
1
(1.00)
0.00448
(1.00)
1
(1.00)
1
(1.00)
9p loss 26 (16%) 135 0.0551
(1.00)
0.513
(1.00)
0.663
(1.00)
0.414
(1.00)
0.0526
(1.00)
0.357
(1.00)
1
(1.00)
0.625
(1.00)
0.591
(1.00)
9q loss 11 (7%) 150 0.199
(1.00)
0.368
(1.00)
1
(1.00)
0.675
(1.00)
0.187
(1.00)
0.212
(1.00)
0.831
(1.00)
0.968
(1.00)
0.301
(1.00)
10p loss 10 (6%) 151 0.203
(1.00)
0.355
(1.00)
0.318
(1.00)
0.0191
(1.00)
0.0663
(1.00)
0.452
(1.00)
0.661
(1.00)
0.342
(1.00)
0.0315
(1.00)
10q loss 9 (6%) 152 0.263
(1.00)
0.676
(1.00)
0.741
(1.00)
0.0248
(1.00)
0.302
(1.00)
0.652
(1.00)
0.792
(1.00)
0.25
(1.00)
0.253
(1.00)
11p loss 12 (7%) 149 0.347
(1.00)
0.237
(1.00)
0.548
(1.00)
0.297
(1.00)
0.168
(1.00)
0.834
(1.00)
0.0806
(1.00)
0.489
(1.00)
1
(1.00)
11q loss 9 (6%) 152 0.356
(1.00)
0.466
(1.00)
0.315
(1.00)
0.469
(1.00)
0.24
(1.00)
0.713
(1.00)
0.36
(1.00)
0.506
(1.00)
1
(1.00)
12q loss 6 (4%) 155 0.335
(1.00)
0.21
(1.00)
0.0819
(1.00)
0.705
(1.00)
0.191
(1.00)
0.0333
(1.00)
1
(1.00)
0.0852
(1.00)
1
(1.00)
13q loss 5 (3%) 156 0.866
(1.00)
1
(1.00)
0.325
(1.00)
0.702
(1.00)
0.356
(1.00)
0.635
(1.00)
0.577
(1.00)
0.148
(1.00)
14q loss 10 (6%) 151 0.208
(1.00)
0.0776
(1.00)
1
(1.00)
0.905
(1.00)
0.879
(1.00)
0.519
(1.00)
0.416
(1.00)
0.816
(1.00)
1
(1.00)
15q loss 10 (6%) 151 0.58
(1.00)
0.328
(1.00)
1
(1.00)
0.117
(1.00)
0.109
(1.00)
0.427
(1.00)
0.812
(1.00)
0.641
(1.00)
0.0315
(1.00)
16p loss 9 (6%) 152 0.606
(1.00)
0.396
(1.00)
0.0853
(1.00)
0.386
(1.00)
0.192
(1.00)
0.81
(1.00)
1
(1.00)
0.862
(1.00)
1
(1.00)
16q loss 14 (9%) 147 0.539
(1.00)
0.941
(1.00)
0.406
(1.00)
0.464
(1.00)
0.124
(1.00)
0.264
(1.00)
1
(1.00)
0.849
(1.00)
0.369
(1.00)
17p loss 32 (20%) 129 0.463
(1.00)
0.351
(1.00)
0.547
(1.00)
0.022
(1.00)
0.0683
(1.00)
0.286
(1.00)
0.927
(1.00)
0.436
(1.00)
0.0541
(1.00)
17q loss 9 (6%) 152 0.858
(1.00)
0.667
(1.00)
0.487
(1.00)
0.0316
(1.00)
0.936
(1.00)
0.368
(1.00)
0.247
(1.00)
0.407
(1.00)
0.253
(1.00)
18p loss 12 (7%) 149 0.278
(1.00)
0.872
(1.00)
1
(1.00)
0.952
(1.00)
0.553
(1.00)
0.362
(1.00)
0.587
(1.00)
0.38
(1.00)
1
(1.00)
18q loss 24 (15%) 137 0.213
(1.00)
0.46
(1.00)
0.505
(1.00)
0.836
(1.00)
0.579
(1.00)
0.224
(1.00)
0.249
(1.00)
0.438
(1.00)
1
(1.00)
19p loss 16 (10%) 145 0.671
(1.00)
0.905
(1.00)
0.283
(1.00)
0.544
(1.00)
0.54
(1.00)
0.284
(1.00)
0.759
(1.00)
0.511
(1.00)
1
(1.00)
19q loss 12 (7%) 149 0.879
(1.00)
0.182
(1.00)
0.364
(1.00)
0.559
(1.00)
0.421
(1.00)
0.233
(1.00)
0.702
(1.00)
0.141
(1.00)
1
(1.00)
20p loss 4 (2%) 157 0.286
(1.00)
0.873
(1.00)
0.304
(1.00)
0.862
(1.00)
0.253
(1.00)
0.726
(1.00)
0.0855
(1.00)
0.307
(1.00)
1
(1.00)
21q loss 29 (18%) 132 0.996
(1.00)
0.668
(1.00)
1
(1.00)
0.647
(1.00)
0.413
(1.00)
0.977
(1.00)
0.852
(1.00)
0.691
(1.00)
1
(1.00)
22q loss 22 (14%) 139 0.655
(1.00)
0.465
(1.00)
1
(1.00)
0.208
(1.00)
0.67
(1.00)
0.694
(1.00)
0.731
(1.00)
0.551
(1.00)
0.525
(1.00)
Xq loss 7 (4%) 154 0.139
(1.00)
0.289
(1.00)
0.702
(1.00)
0.207
(1.00)
0.0874
(1.00)
0.374
(1.00)
1
(1.00)
0.166
(1.00)
0.202
(1.00)
'20p gain mutation analysis' versus 'GENDER'

P value = 0.000128 (Fisher's exact test), Q value = 0.083

Table S1.  Gene #34: '20p gain mutation analysis' versus Clinical Feature #3: 'GENDER'

nPatients FEMALE MALE
ALL 65 96
20P GAIN MUTATED 13 48
20P GAIN WILD-TYPE 52 48

Figure S1.  Get High-res Image Gene #34: '20p gain mutation analysis' versus Clinical Feature #3: 'GENDER'

'20q gain mutation analysis' versus 'GENDER'

P value = 0.00037 (Fisher's exact test), Q value = 0.24

Table S2.  Gene #35: '20q gain mutation analysis' versus Clinical Feature #3: 'GENDER'

nPatients FEMALE MALE
ALL 65 96
20Q GAIN MUTATED 19 56
20Q GAIN WILD-TYPE 46 40

Figure S2.  Get High-res Image Gene #35: '20q gain mutation analysis' versus Clinical Feature #3: 'GENDER'

'1p loss mutation analysis' versus 'PATHOLOGICSPREAD(M)'

P value = 0.000111 (Fisher's exact test), Q value = 0.073

Table S3.  Gene #37: '1p loss mutation analysis' versus Clinical Feature #7: 'PATHOLOGICSPREAD(M)'

nPatients M0 M1 MX
ALL 132 18 11
1P LOSS MUTATED 1 5 0
1P LOSS WILD-TYPE 131 13 11

Figure S3.  Get High-res Image Gene #37: '1p loss mutation analysis' versus Clinical Feature #7: 'PATHOLOGICSPREAD(M)'

'1p loss mutation analysis' versus 'TUMOR.STAGE'

P value = 0.000345 (Fisher's exact test), Q value = 0.22

Table S4.  Gene #37: '1p loss mutation analysis' versus Clinical Feature #8: 'TUMOR.STAGE'

nPatients I II III IV
ALL 25 43 48 29
1P LOSS MUTATED 0 0 0 5
1P LOSS WILD-TYPE 25 43 48 24

Figure S4.  Get High-res Image Gene #37: '1p loss mutation analysis' versus Clinical Feature #8: 'TUMOR.STAGE'

'12p loss mutation analysis' versus 'PATHOLOGY.N'

P value = 0.000243 (Fisher's exact test), Q value = 0.16

Table S5.  Gene #58: '12p loss mutation analysis' versus Clinical Feature #6: 'PATHOLOGY.N'

nPatients N0 N1 N2 N3
ALL 50 57 24 19
12P LOSS MUTATED 10 0 0 1
12P LOSS WILD-TYPE 40 57 24 18

Figure S5.  Get High-res Image Gene #58: '12p loss mutation analysis' versus Clinical Feature #6: 'PATHOLOGY.N'

'12p loss mutation analysis' versus 'TUMOR.STAGE'

P value = 0.000228 (Fisher's exact test), Q value = 0.15

Table S6.  Gene #58: '12p loss mutation analysis' versus Clinical Feature #8: 'TUMOR.STAGE'

nPatients I II III IV
ALL 25 43 48 29
12P LOSS MUTATED 7 3 0 1
12P LOSS WILD-TYPE 18 40 48 28

Figure S6.  Get High-res Image Gene #58: '12p loss mutation analysis' versus Clinical Feature #8: 'TUMOR.STAGE'

Methods & Data
Input
  • Mutation data file = broad_values_by_arm.mutsig.cluster.txt

  • Clinical data file = STAD-TP.clin.merged.picked.txt

  • Number of patients = 161

  • Number of significantly arm-level cnvs = 74

  • Number of selected clinical features = 9

  • Exclude genes that fewer than K tumors have mutations, K = 3

Survival analysis

For survival clinical features, the Kaplan-Meier survival curves of tumors with and without gene mutations were plotted and the statistical significance P values were estimated by logrank test (Bland and Altman 2004) using the 'survdiff' function in R

Student's t-test analysis

For continuous numerical clinical features, two-tailed Student's t test with unequal variance (Lehmann and Romano 2005) was applied to compare the clinical values between tumors with and without gene mutations using 't.test' function in R

Fisher's exact test

For binary or multi-class clinical features (nominal or ordinal), two-tailed Fisher's exact tests (Fisher 1922) were used to estimate the P values using the 'fisher.test' function in R

Chi-square test

For multi-class clinical features (nominal or ordinal), Chi-square tests (Greenwood and Nikulin 1996) were used to estimate the P values using the 'chisq.test' function in R

Q value calculation

For multiple hypothesis correction, Q value is the False Discovery Rate (FDR) analogue of the P value (Benjamini and Hochberg 1995), defined as the minimum FDR at which the test may be called significant. We used the 'Benjamini and Hochberg' method of 'p.adjust' function in R to convert P values into Q values.

Download Results

This is an experimental feature. The full results of the analysis summarized in this report can be downloaded from the TCGA Data Coordination Center.

References
[1] Bland and Altman, Statistics notes: The logrank test, BMJ 328(7447):1073 (2004)
[2] Lehmann and Romano, Testing Statistical Hypotheses (3E ed.), New York: Springer. ISBN 0387988645 (2005)
[3] Fisher, R.A., On the interpretation of chi-square from contingency tables, and the calculation of P, Journal of the Royal Statistical Society 85(1):87-94 (1922)
[4] Greenwood and Nikulin, A guide to chi-squared testing, Wiley, New York. ISBN 047155779X (1996)
[5] Benjamini and Hochberg, Controlling the false discovery rate: a practical and powerful approach to multiple testing, Journal of the Royal Statistical Society Series B 59:289-300 (1995)