Bio-Rad Bio-Plex Software® Upgrades and Conversions - Manual (Page 184)

Bio-Plex Manager Software 6.1 User Guide | Analyzing the Results
172
L INEAR
The Linear equation is:
where a is the intercept and b is the slope of the line.
The simplest method for determining concentrations from a standard curve is
to construct a plot using the linear portion of the response curve. The R
2
integrity value may be used to determine the overall goodness of the linear fit.
A linear regression with an R
2 value of greater then 0.99 is considered a very
good fit.
The primary advantage of this method is that it is extremely simple. The
primary disadvantage is that the linear range of concentrations is small
compared to that which may be obtained using nonlinear regression.
The linear curve is available in linear and semi-log versions.
C UBIC S PLINE
Cubic spline curves are smooth curves that go through every data point. The
model is a cubic polynomial on each interval between data points. In some
cases, a spline curve can work well as a standard curve for interpolation.
However, because the curve is calculated individually for every pair of points,
it does not correspond to any single equation.
The cubic spline curve is applicable to a wide range of assays; however, there
are no built-in biochemical restrictions on the curve shape, and values cannot
be extrapolated.
1,2
P OINT - TO -P OINT
No single equation is available for the point-to-point method. The slope of
each segment of the curve between data points is calculated independently.
The Point-to-Point curve is available in linear and semi-log versions.
bx a y
 
1 The Immunoassay Handbook. David Wild, Editor. Nature Publishing
Group, New York, NY. (2nd Edition, 2001)
2 The GraphPad Guide to Nonlinear Regression. Harvey Moltusky, PhD.
GraphPad Software, San Diego, CA.
BioPlex_6.book Page 172 Friday, September 23, 2011 11:55 AM