Dm. Coder et al., COMPUTING THE CENTRAL LOCATION OF IMMUNOFLUORESCENCE DISTRIBUTIONS - LOGARITHMIC DATA TRANSFORMATIONS ARE NOT ALWAYS APPROPRIATE, Cytometry, 18(2), 1994, pp. 75-78
Citations number
7
Categorie Soggetti
Cytology & Histology","Biochemical Research Methods
The idea of the ''average'' intensity of immunofluorescence data is of
ten poorly defined, with such terms as average, mean, and peak used in
terchangeably. In addition, the common use of logarithmic amplifiers w
ith immunofluorescence data further complicates the problem. Log ampli
fiers permit the display of a wider range of fluorescence intensities.
At the same time, they effect a log transformation of the data. This
transformation decreases the variance resulting in narrower fluorescen
ce distributions, which are assumed to approximate normal distribution
s. When the log transform is used, the distribution mean is the geomet
ric mean of the untransformed data, which is computed simply as the me
an of the channel values. This mean value serves as a simple indicator
of the population center. Despite the prevalence of log transformatio
ns in flow cytometry, this transformation may not yield normally distr
ibuted immunofluorescence data, whereas the square root or other fract
ional power transformations can yield normal distributions. (C) 1994 W
iley-Liss, Inc.