TDI: 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)

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

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.

Author

Bendix Carstensen, bendix.carstensen@regionh.dk

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.

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

Run this code


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

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