BCEA (version 1.0)

contour.bcea: Contour method for objects in the class "bcea"

Description

Produces a scatterplot of the cost-effectiveness plane, with a contour-plot of the bivariate density of the differentials of cost (y-axis) and effectiveness (x-axis)

Usage

## S3 method for class 'bcea':
contour(x, comparison = 1, scale = 0.5, levels = NULL, nlevels = 4, ...)

Arguments

x

A "bcea" object containing the results of the Bayesian modelling and the economic evaluation

comparison

In case of more than 2 interventions being analysed, selects which plot should be made. By default chooses the first possible as the comparator

scale

Scales the plot as a function of the observed standard deviation

levels

Numeric vector of levels at which to draw contour lines

nlevels

Number of levels to be plotted in the contour

...

Additional arguments to 'plot.window', 'title', 'Axis' and 'box', typically graphical parameters such as 'cex.axis'

Value

• Plots the cost-effectiveness plane with a scatterplot of all the simulated values from the (posterior) bivariate distribution of (Delta_e,Delta_c), the differentials of effectiveness and costs; superimposes a contour of the distribution and prints the estimated value of the probability of each quadrant (combination of positive/negative values for both Delta_e and Delta_c)

References

Baio, G., Dawid, A. P. (2011). Probabilistic Sensitivity Analysis in Health Economics. Statistical Methods in Medical Research doi:10.1177/0962280211419832.

Baio G. (2012). Bayesian Methods in Health Economics. CRC/Chapman Hall, London

See Also

bcea ceplane.plot

Examples

# See Baio G., Dawid A.P. (2011) for a detailed description of the 
# Bayesian model and economic problem
#
# Load the processed results of the MCMC simulation model
data(Vaccine)
# 
# Runs the health economic evaluation using BCEA
m <- bcea(e=e,c=c,          # defines the variables of 
                            #  effectiveness and cost
      ref=2,                # selects the 2nd row of (e,c) 
                            #  as containing the reference intervention
      interventions=treats, # defines the labels to be associated 
                            #  with each intervention
      Kmax=50000            # maximum value possible for the willingness 
                            #  to pay threshold; implies that k is chosen 
                            #  in a grid from the interval (0,Kmax)
)
#
# Plots the contour and scatterplot of the bivariate 
# distribution of (Delta_e,Delta_c)
contour(m,          # uses the results of the economic evalaution 
                    #  (a "bcea" object)
      comparison=1, # if more than 2 interventions, selects the 
                    #  pairwise comparison 
      nlevels=4,    # selects the number of levels to be 
                    #  plotted (default=4)
      levels=NULL,  # specifies the actual levels to be plotted 
                    #  (default=NULL, so that R will decide)
      scale=0.5     # scales the bandwiths for both x- and 
                    #  y-axis (default=0.5)
)