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

You choose a slope for terminal half-life.

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 <k@acr.kr>

See also

Slope

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)