Making Data Manageable

摘要

Often in testing groups or treatments, you need to know what has changed and how it has changed during the test or experiment. In comparing an outcome of two conditions, X and Y, you can look at the difference in the outcomes in several ways. The simplest is the difference (X-Y) of the outcomes. This difference, however, is difficult to compare across multiple repeated measures because it can be biased by differences in technique, baseline values or controls. One way to overcome this is to look at the change between X and Y as a ratio or percentage, or the fold change. A widely accepted calculation in biology, and in particular in microarray analyses1 and gene expression, it is also useful in assessing the magnitude of changes over time in other research areas.