02.08.2013 Views

Sample A: Cover Page of Thesis, Project, or Dissertation Proposal

Sample A: Cover Page of Thesis, Project, or Dissertation Proposal

Sample A: Cover Page of Thesis, Project, or Dissertation Proposal

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

mind that they are most aware <strong>of</strong> the experiment and the conditions prevailing when the<br />

measurements were collected.<br />

Materials and Methods<br />

Data<br />

In the following comparisons, only those samples that were judged acceptable, using the sample<br />

cleansing and batch comparison methods described previously (see Chapter 2) were used in any<br />

analysis. This means that the base dataset used in the comparisons is consistent across<br />

experiments (138 Bhattacharjee samples (125 disease, 13 n<strong>or</strong>mal) and 31 Stearman (17 disease<br />

and 14 n<strong>or</strong>mal) samples, see Supplementary Materials f<strong>or</strong> the file names and files. Each <strong>of</strong> the<br />

three alg<strong>or</strong>ithms was used to generate ProbeSet values in these samples (signal intensities were<br />

transf<strong>or</strong>med to log2 space). While the RMA and dCHIP alg<strong>or</strong>ithms yield the full set <strong>of</strong> 12,625<br />

ProbeSet values, the BaFL protocol retained 4,253 Bhattacharjee ProbeSets and 6,506 Stearman<br />

ProbeSets, with 4,200 <strong>of</strong> these being conc<strong>or</strong>dant ProbeSets. That is, in addition to the ProbeSet<br />

values themselves, the primary difference in the input matrices tested f<strong>or</strong> differential expression is<br />

the number <strong>of</strong> ProbeSets considered. This affects the number <strong>of</strong> candidate genes in subsequent<br />

lists that are available f<strong>or</strong> model construction in the final classification analysis. Two types <strong>of</strong><br />

comparisons <strong>of</strong> the three probe cleansing methodologies are made, following a typical analysis<br />

framew<strong>or</strong>k: down selection and validation <strong>of</strong> a candidate list. The first analysis is based on the<br />

down selection to significant features as provided by Welch’s t-test [5], and the validation <strong>of</strong><br />

candidate gene lists is considered with respect to those <strong>of</strong> the <strong>or</strong>iginal investigat<strong>or</strong>s proposals [3,<br />

4].<br />

67

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!