The Kinetics tool allows you to visualize changes in a parameter over time. Using a normal 2D dot plot with "Time" on the x-axis and "Param A" on the y-axis, it can be difficult to see exactly how "Param A" is changing over time. What the kinetics tool does is to split the time scale on the x-axis into many small time slices. Then for each time slice, the value for "Param A" for all the events that occurred within the time slice are combined into one value for "Param A". You can choose several ways to do this, but the default is to take the median value for "Param A", for the time slice. Once there is a value for "Param A" for all time slices, a curve can be generated and drawn.
To create a new kinetics run, click the "Kinetics" button in the sidebar. A pop up menu will allow you to select a few options:
- Plotted Value - The statistic which will be used to combine all of the values in a time slice into a single value. See below for more details
- Value Parameter - The parameter of interest which will be displayed on the y-axis.
- Time Parameter - This parameter which represents Time. Most cytometers call it "Time" but yours may not.
There are statistics which can be used to combine the events of the value parameter for a time slice. The default and most commonly used statistic is to take the median value for all the events in the time slice. But you can choose from the following:
- Event Count
If you are doing kinetics there is a good chance that your cytometer already made a ratio parameter for you. However if you are doing an assay which requires you to take the ratio of two parameters and your cytometer does not do this for you already, you can use the "Custom Parameter" tool to create your own ratio parameter. You can find more information about how to do that here.
Creating Time Ranges
Once you create a kinetics run, you can then create time ranges over your data. To do this select "Range" from the sidebar and click and drag over the range of interest on the plot. Once you create a range, several stats will be shown in the "Information" table.
The following statistics are shown for every time range that is created for a kinetics plot:
- Begin Time - The time where the range starts
- End Time - The time where the range ends
- Slope - The slope of the kinetics curve over the time range. Basically calculated as ([y-value at Tend] - [y-value at Tbegin])/([Tend] - [Tbegin]).
- AUC - The area under the curve for the time range.