Determine slope for the log(y) and x regression manually

You choose a slope for terminal half-life.

Usage

DetSlope(x, y, SubTitle="", sel.1=0, sel.2=0)

Arguments

x: vector values of x-axis, usually time
y: vector values of y-axis, usually concentration
SubTitle: subtitle to be shown on the plot
sel.1: default index of the first element to use
sel.2: default index of the last element to use

Details

Sometimes BestSlope cannot find terminal slope satisfactorily. Then you can use this function to choose manually. It returns the same format result with BestSlope with an attribute indicating used points.

Value

R2: R-squared
R2ADJ: adjusted R-squared
LAMZNPT: number of points used for the slope
LAMZ: negative of the slope, lambda_z
b0: intercept of the regression line
CORRXY: correlation of log(y) and x
LAMZLL: earliest x for lambda_z
LAMZUL: last x for lambda_z
CLSTP: predicted y value at the last point, predicted concentration for the last time point

Author

Kyun-Seop Bae <[email protected]>

Examples

DetSlope(Theoph[Theoph$Subject==1, "Time"], Theoph[Theoph$Subject==1, "conc"])
#>      R2   R2ADJ LAMZNPT    LAMZ      b0  CORRXY  LAMZLL  LAMZUL   CLSTP 
#>      NA      NA       0      NA      NA      NA      NA      NA      NA 
#> attr(,"UsedPoints")
#> integer(0)
DetSlope(Indometh[Indometh$Subject==2, "time"], Indometh[Indometh$Subject==2, "conc"])
#>      R2   R2ADJ LAMZNPT    LAMZ      b0  CORRXY  LAMZLL  LAMZUL   CLSTP 
#>      NA      NA       0      NA      NA      NA      NA      NA      NA 
#> attr(,"UsedPoints")
#> integer(0)