Transformation
The Biomedical Genomics Workbench lets you transform expression values based on logarithm and adding a constant:
Toolbox | Microarray and Small RNA Analysis (
)| Transformation and Normalization | Transform (
)
Select a number of samples ( (
) or (
)) or an experiment (
) and click Next.
This will display a dialog as shown in figure 30.47.
Figure 30.47: Transforming expression values.
At the top, you can select which values to transform (see Selecting transformed and normalized values for analysis).
Next, you can choose three kinds of transformation:
- Logarithm transformation. Transformed expression values will be calculated by taking the logarithm (of the specified type) of the values you have chosen to transform.
- 10.
- 2.
- Natural logarithm.
- Adding a constant. Transformed expression values will be calculated by adding the specified constant to the values you have chosen to transform.
- Square root transformation.
Click Finish to start the tool.