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Important update (January 20th, 2011): the data below have been corrected for the BCR batch which is not necessarily the processing batch. The dataset needs to be reanalyzed.
Correlation between BCR batch and the processing batch for 27k arrays (January 20, 2012):
Significant batch/trait correlations (complete table can be found ):
Survival vs Batch
Summary can be found , batch is significantly correlated with survival:
Likelihood ratio test= 61.35 on 10 df, p=2.007e-09
Wald test = 64.35 on 10 df, p=5.39e-10
Score (logrank) test = 75.35 on 10 df, p=4.066e-12
DNA methylation data analysis
27k dataset, downloaded on December 28, 2011. 219 samples. Note: TCGA is terrible about their standards. I am extracting values for methylated and unmethylated probes from the files for each patient. For this dataset it is 1st and 4th columns. However, for GBM it is 1st and 2nd columns! Unreliable. It seems that the data for GBM was processed differently because standard deviation and the number of beads are missing for GBM. However I noticed that they actually provide negative controls intensity for the green and red dyes.
Technical variables available: batch, amount, concentration, day of shipment, month of shipment, year of shipment, plate row, plate column. Combine day, month and year in a single variable. Info about technical variables:
> head(methNew)
batchID amount concentration plate_column plate_row dateCombined
2 0859 26.7 uL 0.14 ug/uL 1 A 17-3-2010
32 0859 26.7 uL 0.17 ug/uL 1 C 17-3-2010
59 0859 26.7 uL 0.15 ug/uL 1 D 17-3-2010
84 0859 26.7 uL 0.15 ug/uL 1 E 17-3-2010
> table(methNew$batchID)
0859 1186 1284 1303 1332
40 35 50 47 47
> table(methNew$amount)
26.7 uL
219
> table(methNew$concentration)
0.13 ug/uL 0.14 ug/uL 0.15 ug/uL 0.16 ug/uL 0.17 ug/uL
7 50 122 30 10
> table(methNew$plate_column)
1 2 3 4 5 6 7
39 40 40 40 35 23 2
> table(methNew$plate_row)
A B C D E F G H
30 28 28 27 27 27 27 25
> table(methNew$plate_column,methNew$plate_row)
A B C D E F G H
1 5 4 5 5 5 5 5 5
2 5 5 5 5 5 5 5 5
3 5 5 5 5 5 5 5 5
4 5 5 5 5 5 5 5 5
5 5 5 5 4 4 4 4 4
6 4 3 3 3 3 3 3 1
7 1 1 0 0 0 0 0 0
> table(methNew$dateCombined)
11-10-2010 17-3-2010 25-8-2010 27-9-2010 6-10-2010
47 40 35 50 47
> table(methNew$dateCombined,methNew$batchID)
0859 1186 1284 1303 1332
11-10-2010 0 0 0 0 47
17-3-2010 40 0 0 0 0
25-8-2010 0 35 0 0 0
27-9-2010 0 0 50 0 0
6-10-2010 0 0 0 47 0
Exclude "amount" from calculations for the correlations of the first principal components of the data with the technical variables.
Created a matrix of M values, didn't split read and green. Relative variance, no normalization and the outliers:
Based on the plot will look at the first 8 principal components:
Batch and dateCombined are highly correlated with the first principal components (V1 - V8 are the principal components after performing an SVD on unnormalized matrix)
Start by removing the batch. Relative variance and the outliers after removing the batch.
Yikes.
Correlation with the first principal components: