# TDI: Compute Lin's Total deviation index In MethComp: Analysis of Agreement in Method Comparison Studies

## 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

 `1` ```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, bendix.carstensen@regionh.dk

## 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

 ```1 2 3``` ```data(plvol) pw <- to.wide(plvol) with(pw,TDI(Hurley,Nadler)) ```

MethComp documentation built on Jan. 20, 2020, 1:12 a.m.