MethComp (version 1.22.2)

cardiac: Measurement of cardiac output by two different methods.

Description

For each subject cardiac output is measured repeatedly (three to six times) by impedance cardiography (IC) and radionuclide ventriculography (RV).

Usage

data(cardiac)

Format

A data frame with 120 observations on the following 4 variables.

meth

a factor with levels IC RV

item

a numeric vector giving the item number.

repl

a numeric vector with replicate number.

y

the measuremnts of cardiac output.

Source

The dataset is adapted from table 4 in: JM Bland and DG Altman: Measuring agreement in method comparison studies. Statistical Methods in Medical Research, 8:136-160, 1999. Originally supplied to Bland \& Altman by Dr LS Bowling, see: Bowling LS, Sageman WS, O'Connor SM, Cole R, Amundson DE. Lack of agreement between measurement of ejection fraction by impedance cardiography versus radionuclide ventriculography. Critical Care Medicine 1993; 21: 1523-27.

Details

It is not entirely clear from the source whether the replicates are exchangeable within (method,item) or whether they represent pairs of measurements. From the description it looks as if replicates are linked between methods, but in the paper they are treated as if they were not.

Examples

data(cardiac)
cardiac <- Meth(cardiac)
summary(cardiac)
# Visually check exchangeability
plot( cardiac )
plot( perm.repl( cardiac ) )
BA.est(cardiac)
# Run MCmcmc using BRugs for an insufficient amount of iterations
## Not run: card.mi.ir <- MCmcmc( cardiac,
#                                beta=FALSE, random=c("mi","ir"),
#                                n.iter=100, trace=T )
# print( card.mi.ir )## End(Not run)