Bio-Rad Bio-Plex Software® Upgrades and Conversions - Manual (Page 183)

Standard Curve
171
L OGISTIC -5PL
This version of the five-parameter logistic equation has been developed by
Brendan Scientific, creator of StatLIA immunoassay software. The Logistic-
5PL regression type yields the best results for most assays; therefore, this is
the default in Bio-Plex Manager. However, there may be cases in which the
Logistic-4PL equation gives slightly better results.
The Logistic-5PL equation is:
where:
x is the concentration,
y is the response,
a is the estimated response at infinite concentration,
b is the slope of the tangent at midpoint,
c is the midrange concentration or midpoint,
d is the estimated response at zero concentration, and
g is an asymmetry factor.
L OGISTIC -4PL
In certain cases, in which the curve is a perfectly shaped S, the Logistic 4PL
regression may give better results. However, the Logistic-5PL regression has
been shown to be the most robust routine for most Bio-Plex assays.
The Logistic-4PL equation is:
where:
x is the concentration,
y is the response,
a is the estimated response at infinite concentration.
b is the slope of the tangent at midpoint,
c is the midrange concentration or midpoint, and
d is the estimated response at zero concentration.
 
g
b
c
x
d a
d y



 

 
1
 
b
c
x
d a
d y


 
1
BioPlex_6.book Page 171 Friday, September 23, 2011 11:55 AM