Reset a BCEA object

Introduction

When running BCEA, we create objects that belong in a special bcea “class”

data(Vaccine)
m=bcea(eff,cost,ref=2,interventions=treats)
class(m)
#> [1] "bcea" "list"

We may want to run advanced analyses on this object. For instance, we may consider the “mixed analysis”, which accounts for the potential market shares of the interventions being compared

mixedAn(m)=c(.25,.75)
class(m)
#> [1] "mixedAn" "bcea"    "list"

— in this case, we assume that intervention \(t=1\) has 25% of the market and intervetion \(t=2\) has the remaining 75%.

This operation changes the nature of the m object, to which we add relevant quantities/variables and an additional class mixedAn. This unlocks new plotting methods. For instance, when we do

plot(m)
#> Warning in plot.mixedAn(m): 'plot.mixedAn' is deprecated.
#> Use 'evi.plot' instead.
#> See help("Deprecated")

we get a specialised graph, describing the Expected Value of Information comparing the mixed with the optimal strategy (in which we allocate all the shares to the intervention that is most cost-effective, given current evidence). The gray area represent the loss due to “market inefficiency”.

Interestingly, because we do not remove the class bcea from the object m, we can still use the original methods calling them specifically. For instance

BCEA:::plot.bcea(m)

now returns the “standard” graphical summary of the basic economic evaluation performed by bcea().

In addition, methods for which a mixedAn option is not available (e.g. ceac.plot) can be used directly – after all, m is still an object of the class bcea too and so if we try

ceac.plot(m)

R will understand to apply the method ceac.plot.bcea() in the background.

Similar reasoning applies if we use the CEriskav class, which we can do by calling

CEriskav(m)=c(.001,.002,.003)
class(m)
#> [1] "CEriskav" "mixedAn"  "bcea"     "list"

This adds another class to the object m and unlocks other plot methods. Now CEriskav becomes the default class and so

plot(m)

generates the specific graph to perform the analysis including risk aversion. But

BCEA:::plot.mixedAn(m)
#> Warning in BCEA:::plot.mixedAn(m): 'BCEA:::plot.mixedAn' is deprecated.
#> Use 'evi.plot' instead.
#> See help("Deprecated")

applies the specific method to do the mixed analysis.

IF we want to return to the original status and remove the extra credentials generated when calling mixedAn and/or CEriskav, we can simply use the reset_bcea() function.

m=reset_bcea(m)
class(m)
#> [1] "bcea" "list"
plot(m)

- Introduction