TDI {MethComp}

Compute Lin's Total deviation index

Description

This index calculates a value such that a certain fraction of difference between methods will be numerically smaller than this. The TDI is a measure which esentially is a number K such that the interval [-K,K] contains the limits of agreement.

Usage

TDI(y1, y2, p = 0.05, boot = 1000, alpha = 0.05)

Arguments

y1

Measurements by one method.

y2

Measurements by the other method.

p

The fraction of items with differences numerically exceeding the TDI

boot

If numerical, this is the number of bootstraps. If FALSE no confidence interval for the TDI is produced.

alpha

1 - confidende degree.

Details

If boot==FALSE a single number, the TDI is returned. If boot is a number, the median and the 1-alpha/2 central interval based on boot resamples are returned too, in a named vector of length 4.

Value

A list with 3 components. The names of the list are preceeded by the criterion percentage, i.e. the percentage of the population that the TDI is devised to catch.

TDI

The numerically computed value for the TDI. If boot is numeric, a vector of median and a bootstrap c.i. is appended.

TDI

The approximate value of the TDI

Limits of Agreement

Limits of agreement

Author(s)

Bendix Carstensen, [e-mail]

References

LI Lin: Total deviation index for measuring individual agreement with applications in laboratory performance and bioequivalence, Statistics in Medicine, 19, 255-270 (2000)

Examples

data(plvol)
pw <- to.wide(plvol)
with(pw,TDI(Hurley,Nadler))