naac {drda} | R Documentation |
Evaluate the normalized area above the curve (NAAC).
naac(object, xlim, ylim)
object |
fit object as returned by |
xlim |
numeric vector of length 2 with the lower and upped bound of the
integration interval. Default is |
ylim |
numeric vector of length 2 with the lower and upped bound of the
allowed function values. Default is |
The area under the curve (AUC) is the integral of the chosen model
y(x; theta)
with respect to x
.
In real applications the response variable is usually contained within a
known interval. For example, if our response represents relative viability
against a control compound, the curve is expected to be between 0 and 1.
Let ylim = c(yl, yu)
represent the admissible range of our function
y(x; theta)
, that is yl
is its lower bound and yu
its upper bound.
Let xlim = c(xl, xu)
represent the admissible range of the predictor
variable x
. For example, when x
represent the dose, the boundaries
are the minimum and maximum doses we can administer.
To make the AUC value comparable between different compounds and/or studies,
this function sets a hard constraint on both the x
variable and the
function y
. The intervals can always be changed if needed.
The integral calculated by this function is of the piece-wise function
f(x; theta)
defined as
f(x; theta) = yl
, if y(x; theta) < yl
f(x; theta) = y(x; theta)
, if yl <= y(x; theta) <= yu
f(x; theta) = yu
, if y(x; theta) > yu
The AUC is finally normalized by its maximum possible value, that is the
area of the rectangle with width xu - xl
and height yu - yl
.
The normalized area above the curve (NAAC) is simply NAAC = 1 - NAUC
.
Numeric value representing the normalized area above the curve.
nauc
for the Normalized Area Under the Curve
(NAUC).
drda_fit <- drda(response ~ log_dose, data = voropm2)
naac(drda_fit)
naac(drda_fit, xlim = c(6, 8), ylim = c(0.2, 0.5))