The process of gating simply creates a new population. When you collect a sample and import it into the workspace, FlowJo creates a "node" to represent that set of events. When you set a gate to select a subset of the cells, FlowJo creates a new "node"--i.e., a new population. Any operation (graphic display, statistic, gating) that can be performed on the sample can also be performed on a subset of the sample--they are all just populations!

FlowJo organizes this information as "tree"--much like a family tree. The sample is the eldest generation (ancestor). When you gate to create a subset, you generate a new node which can be considered a "child" of the sample. The sample is the parent of the new subset. A second subset created on the sample would be another child of the sample; it is a "sibling" of the first subset. You can then gate on the data in a child to generate yet another generation ("grandchild")... Each new generation is indented another level in the workspace window.

Naming subpopulations is important. You cannot have siblings with the same names, lest confusion arise. In general, you should avoid using duplicate names of subpopulations within any given sample. Click here for more information on naming populations.

To create a subpopulation, you will draw any of several different kinds of gates on a graphic plot of the parent population. Once you have created the appropriate combination of gates and statistics on a sample, you can easily copy the entire analysis at once to another sample, or to an entire set of samples.

Click on one of the following topics related to drawing and manipulating gates:

• Drawing new gates
• Editing existing gates
• Manually entering gate boundaries
• Creating Quadrant gates
• Magnetic Gates
• Copying gates

Or, click here to go the overview on graph windows.