| Histograms display a frequency distribution
of the data, as a function of fluorescence intensity. The histograms
can be smoothed (by default) or unsmoothed; this option has little
effect when more than a few thousand events are in the gate. Shown
below are the same dataset shown with and without smoothing turned
on.
The Y-axis for histograms is the number of cells
falling within each "bin" of the histogram; there are
256 bins for each histogram.
You can manually set the lower and upper limits
on the Y axis; the default is to have FlowJo determine the optimal
limits. To set these limits, use the "Graph
Specifications Dialog", by clicking
on the "i" button in the graph window.
When you copy a histogram graph, two items are placed
on the clipboard. One is the graphic rendition (such as shown above);
the other is a text item containing two columns of text data that
represents the histogram (channel numbers & channel counts).
When you paste into a spreadsheet, you will create the two new columns
of the histogram data. (Note: a few graphics programs
will preferentially paste a text item (the column data) instead
of a graphic item from the clipboard. If you encounter this
problem, set the Preference such that FlowJo only copies the graphic
item onto the clipboard.)
See also the page on CDF
displays.
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