The primary objective of microarray study is to determine the change in the expression levels of a set of genes across samples exposed to different conditions. Expression levels are usually the fluorescent intensity values, which are indirect measurements of m-RNA abundance in the biological samples. Hybridization experiments are either single color or double color that are labeled with fluorescent dyes such as Cy5 and Cy3. In addition to biological variations, intensity measurements are subject to other sources of variations such as array spotting, hybridization, labeling, scanning, etc. These factors not only affect intensities, but also gene expression. More...
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