Bladder Urothelial Carcinoma: Correlation between molecular cancer subtypes and selected clinical features
Maintained by TCGA GDAC Team (Broad Institute/Dana-Farber Cancer Institute/Harvard Medical School)
Overview
Introduction

This pipeline computes the correlation between cancer subtypes identified by different molecular patterns and selected clinical features.

Summary

Testing the association between subtypes identified by 8 different clustering approaches and 4 clinical features across 102 patients, one significant finding detected with P value < 0.05.

  • 3 subtypes identified in current cancer cohort by 'CN CNMF'. These subtypes do not correlate to any clinical features.

  • 3 subtypes identified in current cancer cohort by 'METHLYATION CNMF'. These subtypes do not correlate to any clinical features.

  • CNMF clustering analysis on RPPA data identified 4 subtypes that correlate to 'Time to Death'.

  • Consensus hierarchical clustering analysis on RPPA data identified 3 subtypes that do not correlate to any clinical features.

  • CNMF clustering analysis on sequencing-based mRNA expression data identified 4 subtypes that do not correlate to any clinical features.

  • Consensus hierarchical clustering analysis on sequencing-based mRNA expression data identified 3 subtypes that do not correlate to any clinical features.

  • CNMF clustering analysis on sequencing-based miR expression data identified 3 subtypes that do not correlate to any clinical features.

  • Consensus hierarchical clustering analysis on sequencing-based miR expression data identified 3 subtypes that do not correlate to any clinical features.

Results
Overview of the results

Table 1.  Get Full Table Overview of the association between subtypes identified by 8 different clustering approaches and 4 clinical features. Shown in the table are P values from statistical tests. Thresholded by P value < 0.05, one significant finding detected.

Clinical
Features
Time
to
Death
AGE GENDER KARNOFSKY
PERFORMANCE
SCORE
Statistical Tests logrank test ANOVA Fisher's exact test ANOVA
CN CNMF 0.679 0.969 0.313 0.409
METHLYATION CNMF 0.131 0.759 0.457 0.279
RPPA CNMF subtypes 0.0407 0.473 0.633 0.465
RPPA cHierClus subtypes 0.093 0.164 0.196 0.342
RNAseq CNMF subtypes 0.191 0.285 0.25 0.477
RNAseq cHierClus subtypes 0.0732 0.996 0.341 0.909
MIRseq CNMF subtypes 0.243 0.364 0.302 0.504
MIRseq cHierClus subtypes 0.63 0.195 0.795 0.795
Clustering Approach #1: 'CN CNMF'

Table S1.  Get Full Table Description of clustering approach #1: 'CN CNMF'

Cluster Labels 1 2 3
Number of samples 27 41 20
'CN CNMF' versus 'Time to Death'

P value = 0.679 (logrank test)

Table S2.  Clustering Approach #1: 'CN CNMF' versus Clinical Feature #1: 'Time to Death'

nPatients nDeath Duration Range (Median), Month
ALL 84 26 0.4 - 118.9 (7.3)
subtype1 25 7 2.1 - 75.3 (6.7)
subtype2 40 13 0.5 - 37.8 (7.2)
subtype3 19 6 0.4 - 118.9 (7.8)

Figure S1.  Get High-res Image Clustering Approach #1: 'CN CNMF' versus Clinical Feature #1: 'Time to Death'

'CN CNMF' versus 'AGE'

P value = 0.969 (ANOVA)

Table S3.  Clustering Approach #1: 'CN CNMF' versus Clinical Feature #2: 'AGE'

nPatients Mean (Std.Dev)
ALL 87 67.2 (11.0)
subtype1 26 67.3 (11.3)
subtype2 41 66.9 (11.9)
subtype3 20 67.7 (9.3)

Figure S2.  Get High-res Image Clustering Approach #1: 'CN CNMF' versus Clinical Feature #2: 'AGE'

'CN CNMF' versus 'GENDER'

P value = 0.313 (Fisher's exact test)

Table S4.  Clustering Approach #1: 'CN CNMF' versus Clinical Feature #3: 'GENDER'

nPatients FEMALE MALE
ALL 27 61
subtype1 7 20
subtype2 11 30
subtype3 9 11

Figure S3.  Get High-res Image Clustering Approach #1: 'CN CNMF' versus Clinical Feature #3: 'GENDER'

'CN CNMF' versus 'KARNOFSKY.PERFORMANCE.SCORE'

P value = 0.409 (ANOVA)

Table S5.  Clustering Approach #1: 'CN CNMF' versus Clinical Feature #4: 'KARNOFSKY.PERFORMANCE.SCORE'

nPatients Mean (Std.Dev)
ALL 23 77.8 (18.6)
subtype1 9 84.4 (8.8)
subtype2 9 73.3 (24.0)
subtype3 5 74.0 (20.7)

Figure S4.  Get High-res Image Clustering Approach #1: 'CN CNMF' versus Clinical Feature #4: 'KARNOFSKY.PERFORMANCE.SCORE'

Clustering Approach #2: 'METHLYATION CNMF'

Table S6.  Get Full Table Description of clustering approach #2: 'METHLYATION CNMF'

Cluster Labels 1 2 3
Number of samples 32 36 34
'METHLYATION CNMF' versus 'Time to Death'

P value = 0.131 (logrank test)

Table S7.  Clustering Approach #2: 'METHLYATION CNMF' versus Clinical Feature #1: 'Time to Death'

nPatients nDeath Duration Range (Median), Month
ALL 98 30 0.4 - 118.9 (7.2)
subtype1 31 7 0.8 - 118.9 (7.6)
subtype2 35 14 0.4 - 75.3 (7.8)
subtype3 32 9 0.7 - 37.8 (6.7)

Figure S5.  Get High-res Image Clustering Approach #2: 'METHLYATION CNMF' versus Clinical Feature #1: 'Time to Death'

'METHLYATION CNMF' versus 'AGE'

P value = 0.759 (ANOVA)

Table S8.  Clustering Approach #2: 'METHLYATION CNMF' versus Clinical Feature #2: 'AGE'

nPatients Mean (Std.Dev)
ALL 101 67.1 (10.6)
subtype1 31 67.0 (9.7)
subtype2 36 68.1 (9.8)
subtype3 34 66.2 (12.2)

Figure S6.  Get High-res Image Clustering Approach #2: 'METHLYATION CNMF' versus Clinical Feature #2: 'AGE'

'METHLYATION CNMF' versus 'GENDER'

P value = 0.457 (Fisher's exact test)

Table S9.  Clustering Approach #2: 'METHLYATION CNMF' versus Clinical Feature #3: 'GENDER'

nPatients FEMALE MALE
ALL 29 73
subtype1 10 22
subtype2 12 24
subtype3 7 27

Figure S7.  Get High-res Image Clustering Approach #2: 'METHLYATION CNMF' versus Clinical Feature #3: 'GENDER'

'METHLYATION CNMF' versus 'KARNOFSKY.PERFORMANCE.SCORE'

P value = 0.279 (ANOVA)

Table S10.  Clustering Approach #2: 'METHLYATION CNMF' versus Clinical Feature #4: 'KARNOFSKY.PERFORMANCE.SCORE'

nPatients Mean (Std.Dev)
ALL 26 79.2 (17.9)
subtype1 8 87.5 (4.6)
subtype2 4 72.5 (23.6)
subtype3 14 76.4 (20.2)

Figure S8.  Get High-res Image Clustering Approach #2: 'METHLYATION CNMF' versus Clinical Feature #4: 'KARNOFSKY.PERFORMANCE.SCORE'

Clustering Approach #3: 'RPPA CNMF subtypes'

Table S11.  Get Full Table Description of clustering approach #3: 'RPPA CNMF subtypes'

Cluster Labels 1 2 3 4
Number of samples 12 10 14 17
'RPPA CNMF subtypes' versus 'Time to Death'

P value = 0.0407 (logrank test)

Table S12.  Clustering Approach #3: 'RPPA CNMF subtypes' versus Clinical Feature #1: 'Time to Death'

nPatients nDeath Duration Range (Median), Month
ALL 52 20 0.4 - 118.9 (8.3)
subtype1 12 4 5.7 - 61.9 (10.6)
subtype2 10 5 1.8 - 100.5 (5.5)
subtype3 13 2 0.5 - 19.5 (6.6)
subtype4 17 9 0.4 - 118.9 (14.9)

Figure S9.  Get High-res Image Clustering Approach #3: 'RPPA CNMF subtypes' versus Clinical Feature #1: 'Time to Death'

'RPPA CNMF subtypes' versus 'AGE'

P value = 0.473 (ANOVA)

Table S13.  Clustering Approach #3: 'RPPA CNMF subtypes' versus Clinical Feature #2: 'AGE'

nPatients Mean (Std.Dev)
ALL 52 67.3 (9.8)
subtype1 12 63.9 (9.2)
subtype2 10 69.5 (9.3)
subtype3 13 66.5 (10.2)
subtype4 17 69.1 (10.3)

Figure S10.  Get High-res Image Clustering Approach #3: 'RPPA CNMF subtypes' versus Clinical Feature #2: 'AGE'

'RPPA CNMF subtypes' versus 'GENDER'

P value = 0.633 (Fisher's exact test)

Table S14.  Clustering Approach #3: 'RPPA CNMF subtypes' versus Clinical Feature #3: 'GENDER'

nPatients FEMALE MALE
ALL 21 32
subtype1 6 6
subtype2 5 5
subtype3 5 9
subtype4 5 12

Figure S11.  Get High-res Image Clustering Approach #3: 'RPPA CNMF subtypes' versus Clinical Feature #3: 'GENDER'

'RPPA CNMF subtypes' versus 'KARNOFSKY.PERFORMANCE.SCORE'

P value = 0.465 (ANOVA)

Table S15.  Clustering Approach #3: 'RPPA CNMF subtypes' versus Clinical Feature #4: 'KARNOFSKY.PERFORMANCE.SCORE'

nPatients Mean (Std.Dev)
ALL 11 80.0 (16.7)
subtype1 5 88.0 (4.5)
subtype2 1 70.0 (NA)
subtype3 1 60.0 (NA)
subtype4 4 77.5 (25.0)

Figure S12.  Get High-res Image Clustering Approach #3: 'RPPA CNMF subtypes' versus Clinical Feature #4: 'KARNOFSKY.PERFORMANCE.SCORE'

Clustering Approach #4: 'RPPA cHierClus subtypes'

Table S16.  Get Full Table Description of clustering approach #4: 'RPPA cHierClus subtypes'

Cluster Labels 1 2 3
Number of samples 14 17 22
'RPPA cHierClus subtypes' versus 'Time to Death'

P value = 0.093 (logrank test)

Table S17.  Clustering Approach #4: 'RPPA cHierClus subtypes' versus Clinical Feature #1: 'Time to Death'

nPatients nDeath Duration Range (Median), Month
ALL 52 20 0.4 - 118.9 (8.3)
subtype1 14 5 1.9 - 61.9 (8.3)
subtype2 17 10 0.4 - 118.9 (8.2)
subtype3 21 5 0.5 - 100.5 (7.7)

Figure S13.  Get High-res Image Clustering Approach #4: 'RPPA cHierClus subtypes' versus Clinical Feature #1: 'Time to Death'

'RPPA cHierClus subtypes' versus 'AGE'

P value = 0.164 (ANOVA)

Table S18.  Clustering Approach #4: 'RPPA cHierClus subtypes' versus Clinical Feature #2: 'AGE'

nPatients Mean (Std.Dev)
ALL 52 67.3 (9.8)
subtype1 14 63.5 (9.6)
subtype2 17 70.2 (9.0)
subtype3 21 67.5 (10.2)

Figure S14.  Get High-res Image Clustering Approach #4: 'RPPA cHierClus subtypes' versus Clinical Feature #2: 'AGE'

'RPPA cHierClus subtypes' versus 'GENDER'

P value = 0.196 (Fisher's exact test)

Table S19.  Clustering Approach #4: 'RPPA cHierClus subtypes' versus Clinical Feature #3: 'GENDER'

nPatients FEMALE MALE
ALL 21 32
subtype1 8 6
subtype2 7 10
subtype3 6 16

Figure S15.  Get High-res Image Clustering Approach #4: 'RPPA cHierClus subtypes' versus Clinical Feature #3: 'GENDER'

'RPPA cHierClus subtypes' versus 'KARNOFSKY.PERFORMANCE.SCORE'

P value = 0.342 (ANOVA)

Table S20.  Clustering Approach #4: 'RPPA cHierClus subtypes' versus Clinical Feature #4: 'KARNOFSKY.PERFORMANCE.SCORE'

nPatients Mean (Std.Dev)
ALL 11 80.0 (16.7)
subtype1 4 90.0 (0.0)
subtype2 4 72.5 (23.6)
subtype3 3 76.7 (15.3)

Figure S16.  Get High-res Image Clustering Approach #4: 'RPPA cHierClus subtypes' versus Clinical Feature #4: 'KARNOFSKY.PERFORMANCE.SCORE'

Clustering Approach #5: 'RNAseq CNMF subtypes'

Table S21.  Get Full Table Description of clustering approach #5: 'RNAseq CNMF subtypes'

Cluster Labels 1 2 3 4
Number of samples 35 17 25 10
'RNAseq CNMF subtypes' versus 'Time to Death'

P value = 0.191 (logrank test)

Table S22.  Clustering Approach #5: 'RNAseq CNMF subtypes' versus Clinical Feature #1: 'Time to Death'

nPatients nDeath Duration Range (Median), Month
ALL 83 25 0.4 - 118.9 (7.2)
subtype1 32 9 0.5 - 100.5 (7.1)
subtype2 17 8 4.1 - 118.9 (6.7)
subtype3 25 6 0.4 - 75.3 (8.2)
subtype4 9 2 1.8 - 11.1 (5.1)

Figure S17.  Get High-res Image Clustering Approach #5: 'RNAseq CNMF subtypes' versus Clinical Feature #1: 'Time to Death'

'RNAseq CNMF subtypes' versus 'AGE'

P value = 0.285 (ANOVA)

Table S23.  Clustering Approach #5: 'RNAseq CNMF subtypes' versus Clinical Feature #2: 'AGE'

nPatients Mean (Std.Dev)
ALL 86 67.0 (11.1)
subtype1 34 67.6 (11.2)
subtype2 17 63.2 (9.8)
subtype3 25 66.9 (12.1)
subtype4 10 71.6 (9.9)

Figure S18.  Get High-res Image Clustering Approach #5: 'RNAseq CNMF subtypes' versus Clinical Feature #2: 'AGE'

'RNAseq CNMF subtypes' versus 'GENDER'

P value = 0.25 (Fisher's exact test)

Table S24.  Clustering Approach #5: 'RNAseq CNMF subtypes' versus Clinical Feature #3: 'GENDER'

nPatients FEMALE MALE
ALL 27 60
subtype1 8 27
subtype2 4 13
subtype3 10 15
subtype4 5 5

Figure S19.  Get High-res Image Clustering Approach #5: 'RNAseq CNMF subtypes' versus Clinical Feature #3: 'GENDER'

'RNAseq CNMF subtypes' versus 'KARNOFSKY.PERFORMANCE.SCORE'

P value = 0.477 (ANOVA)

Table S25.  Clustering Approach #5: 'RNAseq CNMF subtypes' versus Clinical Feature #4: 'KARNOFSKY.PERFORMANCE.SCORE'

nPatients Mean (Std.Dev)
ALL 24 78.3 (18.3)
subtype1 10 77.0 (19.5)
subtype2 7 85.7 (7.9)
subtype3 6 73.3 (25.8)
subtype4 1 70.0 (NA)

Figure S20.  Get High-res Image Clustering Approach #5: 'RNAseq CNMF subtypes' versus Clinical Feature #4: 'KARNOFSKY.PERFORMANCE.SCORE'

Clustering Approach #6: 'RNAseq cHierClus subtypes'

Table S26.  Get Full Table Description of clustering approach #6: 'RNAseq cHierClus subtypes'

Cluster Labels 1 2 3
Number of samples 25 42 20
'RNAseq cHierClus subtypes' versus 'Time to Death'

P value = 0.0732 (logrank test)

Table S27.  Clustering Approach #6: 'RNAseq cHierClus subtypes' versus Clinical Feature #1: 'Time to Death'

nPatients nDeath Duration Range (Median), Month
ALL 83 25 0.4 - 118.9 (7.2)
subtype1 25 6 0.4 - 75.3 (8.3)
subtype2 39 10 0.5 - 100.5 (6.7)
subtype3 19 9 1.8 - 118.9 (5.9)

Figure S21.  Get High-res Image Clustering Approach #6: 'RNAseq cHierClus subtypes' versus Clinical Feature #1: 'Time to Death'

'RNAseq cHierClus subtypes' versus 'AGE'

P value = 0.996 (ANOVA)

Table S28.  Clustering Approach #6: 'RNAseq cHierClus subtypes' versus Clinical Feature #2: 'AGE'

nPatients Mean (Std.Dev)
ALL 86 67.0 (11.1)
subtype1 25 67.0 (12.0)
subtype2 41 67.1 (10.9)
subtype3 20 66.8 (11.0)

Figure S22.  Get High-res Image Clustering Approach #6: 'RNAseq cHierClus subtypes' versus Clinical Feature #2: 'AGE'

'RNAseq cHierClus subtypes' versus 'GENDER'

P value = 0.341 (Fisher's exact test)

Table S29.  Clustering Approach #6: 'RNAseq cHierClus subtypes' versus Clinical Feature #3: 'GENDER'

nPatients FEMALE MALE
ALL 27 60
subtype1 10 15
subtype2 10 32
subtype3 7 13

Figure S23.  Get High-res Image Clustering Approach #6: 'RNAseq cHierClus subtypes' versus Clinical Feature #3: 'GENDER'

'RNAseq cHierClus subtypes' versus 'KARNOFSKY.PERFORMANCE.SCORE'

P value = 0.909 (ANOVA)

Table S30.  Clustering Approach #6: 'RNAseq cHierClus subtypes' versus Clinical Feature #4: 'KARNOFSKY.PERFORMANCE.SCORE'

nPatients Mean (Std.Dev)
ALL 24 78.3 (18.3)
subtype1 7 75.7 (24.4)
subtype2 12 79.2 (18.3)
subtype3 5 80.0 (10.0)

Figure S24.  Get High-res Image Clustering Approach #6: 'RNAseq cHierClus subtypes' versus Clinical Feature #4: 'KARNOFSKY.PERFORMANCE.SCORE'

Clustering Approach #7: 'MIRseq CNMF subtypes'

Table S31.  Get Full Table Description of clustering approach #7: 'MIRseq CNMF subtypes'

Cluster Labels 1 2 3
Number of samples 22 52 26
'MIRseq CNMF subtypes' versus 'Time to Death'

P value = 0.243 (logrank test)

Table S32.  Clustering Approach #7: 'MIRseq CNMF subtypes' versus Clinical Feature #1: 'Time to Death'

nPatients nDeath Duration Range (Median), Month
ALL 96 30 0.4 - 118.9 (7.3)
subtype1 19 3 0.8 - 118.9 (6.2)
subtype2 51 20 0.4 - 61.9 (7.3)
subtype3 26 7 0.5 - 100.5 (8.5)

Figure S25.  Get High-res Image Clustering Approach #7: 'MIRseq CNMF subtypes' versus Clinical Feature #1: 'Time to Death'

'MIRseq CNMF subtypes' versus 'AGE'

P value = 0.364 (ANOVA)

Table S33.  Clustering Approach #7: 'MIRseq CNMF subtypes' versus Clinical Feature #2: 'AGE'

nPatients Mean (Std.Dev)
ALL 99 67.4 (10.5)
subtype1 21 69.5 (9.8)
subtype2 52 66.0 (10.9)
subtype3 26 68.4 (10.3)

Figure S26.  Get High-res Image Clustering Approach #7: 'MIRseq CNMF subtypes' versus Clinical Feature #2: 'AGE'

'MIRseq CNMF subtypes' versus 'GENDER'

P value = 0.302 (Fisher's exact test)

Table S34.  Clustering Approach #7: 'MIRseq CNMF subtypes' versus Clinical Feature #3: 'GENDER'

nPatients FEMALE MALE
ALL 29 71
subtype1 4 18
subtype2 15 37
subtype3 10 16

Figure S27.  Get High-res Image Clustering Approach #7: 'MIRseq CNMF subtypes' versus Clinical Feature #3: 'GENDER'

'MIRseq CNMF subtypes' versus 'KARNOFSKY.PERFORMANCE.SCORE'

P value = 0.504 (ANOVA)

Table S35.  Clustering Approach #7: 'MIRseq CNMF subtypes' versus Clinical Feature #4: 'KARNOFSKY.PERFORMANCE.SCORE'

nPatients Mean (Std.Dev)
ALL 25 78.8 (18.1)
subtype1 5 86.0 (8.9)
subtype2 16 75.6 (21.3)
subtype3 4 82.5 (9.6)

Figure S28.  Get High-res Image Clustering Approach #7: 'MIRseq CNMF subtypes' versus Clinical Feature #4: 'KARNOFSKY.PERFORMANCE.SCORE'

Clustering Approach #8: 'MIRseq cHierClus subtypes'

Table S36.  Get Full Table Description of clustering approach #8: 'MIRseq cHierClus subtypes'

Cluster Labels 1 2 3
Number of samples 21 67 12
'MIRseq cHierClus subtypes' versus 'Time to Death'

P value = 0.63 (logrank test)

Table S37.  Clustering Approach #8: 'MIRseq cHierClus subtypes' versus Clinical Feature #1: 'Time to Death'

nPatients nDeath Duration Range (Median), Month
ALL 96 30 0.4 - 118.9 (7.3)
subtype1 18 4 1.5 - 118.9 (6.1)
subtype2 66 22 0.4 - 100.5 (7.8)
subtype3 12 4 0.8 - 46.8 (5.6)

Figure S29.  Get High-res Image Clustering Approach #8: 'MIRseq cHierClus subtypes' versus Clinical Feature #1: 'Time to Death'

'MIRseq cHierClus subtypes' versus 'AGE'

P value = 0.195 (ANOVA)

Table S38.  Clustering Approach #8: 'MIRseq cHierClus subtypes' versus Clinical Feature #2: 'AGE'

nPatients Mean (Std.Dev)
ALL 99 67.4 (10.5)
subtype1 20 70.8 (9.9)
subtype2 67 66.1 (11.0)
subtype3 12 68.5 (7.6)

Figure S30.  Get High-res Image Clustering Approach #8: 'MIRseq cHierClus subtypes' versus Clinical Feature #2: 'AGE'

'MIRseq cHierClus subtypes' versus 'GENDER'

P value = 0.795 (Fisher's exact test)

Table S39.  Clustering Approach #8: 'MIRseq cHierClus subtypes' versus Clinical Feature #3: 'GENDER'

nPatients FEMALE MALE
ALL 29 71
subtype1 5 16
subtype2 21 46
subtype3 3 9

Figure S31.  Get High-res Image Clustering Approach #8: 'MIRseq cHierClus subtypes' versus Clinical Feature #3: 'GENDER'

'MIRseq cHierClus subtypes' versus 'KARNOFSKY.PERFORMANCE.SCORE'

P value = 0.795 (ANOVA)

Table S40.  Clustering Approach #8: 'MIRseq cHierClus subtypes' versus Clinical Feature #4: 'KARNOFSKY.PERFORMANCE.SCORE'

nPatients Mean (Std.Dev)
ALL 25 78.8 (18.1)
subtype1 3 83.3 (11.5)
subtype2 19 77.4 (20.0)
subtype3 3 83.3 (11.5)

Figure S32.  Get High-res Image Clustering Approach #8: 'MIRseq cHierClus subtypes' versus Clinical Feature #4: 'KARNOFSKY.PERFORMANCE.SCORE'

Methods & Data
Input
  • Cluster data file = BLCA.mergedcluster.txt

  • Clinical data file = BLCA.clin.merged.picked.txt

  • Number of patients = 102

  • Number of clustering approaches = 8

  • Number of selected clinical features = 4

  • Exclude small clusters that include fewer than K patients, K = 3

Clustering approaches
CNMF clustering

consensus non-negative matrix factorization clustering approach (Brunet et al. 2004)

Consensus hierarchical clustering

Resampling-based clustering method (Monti et al. 2003)

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

ANOVA analysis

For continuous numerical clinical features, one-way analysis of variance (Howell 2002) was applied to compare the clinical values between tumor subtypes using 'anova' function in R

Fisher's exact test

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

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] Brunet et al., Metagenes and molecular pattern discovery using matrix factorization, PNAS 101(12):4164-9 (2004)
[3] Bland and Altman, Statistics notes: The logrank test, BMJ 328(7447):1073 (2004)
[4] Howell, D, Statistical Methods for Psychology. (5th ed.), Duxbury Press:324-5 (2002)
[5] 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)