Negative values are not a consequence of the biexponential scaling. *update 5/13/08* There was another question posted about this on the list, and Dr. Measurements are still linearly related to the fluorescence of the Increasing negative values, but you are not decreasing any otherīut the bottom line is that we are not displaying measuredįluorescence values - those of course are always positive. Systematically increase the mean of the distribution (you are always Set these negative values to zero, because they you would Reach into the negative values just as far. But measurement errorsĪre always symmetrically distributed-so the distribution has to
Zero, and the error is fairly large, then of course we expect theĭistribution to rise to the positive values - with 95% of the valuesīeing within a few SD of the "true" value. Look at it another way: there is a distribution of measurementsĪround the true value that distribution is dictated by the error in Value thus, frequently this value is less than zero. The compensation channels are aggregated into the final computed Likewise, for compensation, additional measurement errors from all of Subtraction, the measurement is less than zero. Measurement for the baseline, because of the errors involved. So,įor "negative" cells (cells with little or no fluorescence), there'sĪ chance that the measurement for the cell will be less than the Measurement of both the fluorescence as well as the baseline. Baseline is measuredĭuring the time between pulses. Measurement has "baseline" subtracted from it. When the fluorescence is detected off the PMT, the voltage
#FLOWJO BIEXPONENTIAL SOFTWARE#
Software (in the case of compensation), before it is displayed. The corrected measurement hasīeen manipulated by both the instrument firmware, and possibly However, what we areĭisplaying on the graphs is no longer fluorescence, it is a corrected There is no meaning to negativeįluorescence there is no such thing. The user complained that negative fluorescence is Transformations (Biexponential, Logicle, Hyperlog, etc.), which show Recently, I was queried by a user who complained about the new data This question came up in my email as well just last week, so it's nice to get a real scientist's (as opposed to us flow-jocks) perspective: Roederer on Purdue list archives discussing the topic of negative fluorescence.
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