The Global Averaging transformation scales all of the experiments in your project so that they all have the same average value.
To apply the Global Averaging transformation to an existing ArrayStar project, open the Edit Data Transformations dialog by selecting Data > Edit Data Transformations from the main menu.
Note: You may also apply the Global Averaging transformation in the Set Up Preprocessing step of the Project Setup Wizard.
After the dialog opens, click the Add button to populate the dialog. From the Type drop-down menu, select Global Averaging.
In the Average method section, select Mean or Median. The new average of each experiment will be determined by taking the average of averages.
Note: If Mean is specified as the averaging method, the geometric mean will be calculated, which utilizes the logarithm of values rather than the raw values.
This transformation can be used as a simple gene-level normalization method when other normalization is not available or when data sets were loaded that were not compatible at the probe level, such as different microarray platforms, or microarray and sequence data together.
When applying the Global Averaging transformation, the values in each experiment are all linearly scaled by the same factor. Thus, the ratios between values in each experiment will not change, but ratios between experiments may change.
To apply this transformation to an existing ArrayStar project, open the Edit Data Transformations dialog by selecting Data > Edit Data Transformations from any ArrayStar view. You may also scale experiments using this method in the Set Up Preprocessing step of the Project Setup Wizard.