One population, two percentages
Suppose a sample contains 100,000 total events, 35,000 events in a parent gate and 21,000 in its child. The child is 60% of its parent but 21% of the total. Neither value is wrong: they answer different questions.
%Parent = child events / immediate parent events × 100
%Total = child events / total events × 100
Here, total means the sample root, All Events. Always check the actual reference population before comparing exported percentages.
Try different event counts
- %Parent
- 60%
- %Total
- 21%
Zero child events gives 0% when the denominator is positive. A zero denominator is undefined, not 0%. This calculator illustrates counts only; it does not validate gates or estimate uncertainty.
Why two gates may not be comparable
Two identically named gates can have different parents. A CD4+ percentage within T cells is not the same measurement as a CD4+ percentage within all live cells. Keep the population path with the statistic, and compare the same definition across samples.
Mean fluorescence intensity and median intensity
FlowApp's MFI is the arithmetic mean of event values in the selected channel and population. Median intensity is the middle value after sorting those values. Neither is a percentage or an absolute concentration.
The abbreviation MFI is used inconsistently outside FlowApp. Write the full statistic name and channel in the report, rather than assuming an exported “MFI” column always means the same thing.
- Compare the same channel, population definition and processing state.
- A plot's display transformation should not be confused with calibrated measurement units.
- Mean and median can diverge with a skewed distribution or extreme events; inspect the distribution, not only one number.
Per-event statistics are not group replicate counts
A fluorescence median is calculated from events in one sample. A group mean in the report summarizes sample-level measurements. Thousands of events do not supply thousands of independent donors or experimental units.
Preserve individual sample values alongside the group summary. Confirm biological units, technical repeats and pairing before inference. Missing values should remain missing, not become zero.
Reference and next steps
FlowJo's table statistics documentation defines parent/total frequencies and common summaries. The calculator and FlowApp-specific descriptions here are based on this application's implementation.
Continue with report settings and charts or try the demo cohort.