gets (version 0.3)

isattest: Indicator Saturation Test

Description

Takes a 'gets' object returned by the isat function as input and returns the results of a hypothesis test on the time-varying intercept or long-run equilibrium against a specified null-hypothesis for a chosen level of significance - see Pretis (2015).

Usage

isattest(x, hnull=0, lr=FALSE, ci.pval=0.99, plot=TRUE, plot.turn=FALSE,
    biascorr=FALSE)

Arguments

x

a 'gets' object obtained with the isat function

hnull

numeric. the null-hypothesis value to be tested against.

lr

logical. If TRUE and 'x' contains autoregressive elements, then isattest tests on the long-run equilibrium path. See Pretis (2015).

ci.pval

numeric between 0 and 1. Default is 0.99, the level of significance for the confidence interval of the test against 'hnull'.

plot

logical. If TRUE, then a plot showing the coefficient path and bias relative to 'hnull' is shown.

plot.turn

logical. If TRUE, then the plot output adds the time of the breaks to the plot showing the bias relative to 'hnull'.

biascorr

logical. If TRUE, then the coefficient path is bias-corrected using biascorr. This is only valid for the non-dynamic test without additional covariates.

Value

• A Tx4 matrix (with T = number of observations) where the first two columns denote the confidence interval of the coefficient path (or the long-run equilibrium path if 'lr=TRUE'). The third and fourth column denote the bias of the coefficient path relative to the chosen null-hypothesis, where 'bias.high' denotes the bias when the series tested is above the hypothesized value, and 'bias.low' denotes the bias when the series tested is significantly below the hypothesized value.

Details

The function tests the coefficient path (or long-run equilibrium path) against a specified null hypothesis at a chosen level of significance. If conducted on an isat model of a forecast error or relative forecast differential, then this corresponds to the test of time-varying predictive accuracy of Pretis (2015). The resulting output plot shows the coefficient path in the top panel (where 'hnull' is plotted as dotted lines), with the bias (significant difference relative to 'hnull') in the lower panel.

References

Pretis, F. (2015): 'Testing for time-varying predictive accuracy using bias-corrected indicator saturation'. Oxford Department of Economics Discussion Paper.

See Also

isat, coef.gets, plot.gets, biascorr, isatvar

Examples

##Using artificial data:
#set.seed(123)
#d <- matrix(0,100,1)
#d[35:55] <- 1
#e <- rnorm(100, 0, 1)
#y <- d*2  +e 
#plot(y, type="l")

##Static Test against hnull=0 using bias-correction:

#ys <- isat(y, sis=TRUE, iis=FALSE, tis=FALSE, t.pval=0.01)
#isattest(ys, hnull=0, lr=FALSE, ci.pval = 0.99, plot.turn = FALSE, biascorr=TRUE)

##Dynamic Test of the long-run equilibrium against hnull=2 with breakpoints labelled in the plot:

#ys <- isat(y, sis=TRUE, iis=FALSE, tis=FALSE, t.pval=0.01, ar=1:2)
#isattest(ys, hnull=2, lr=TRUE, ci.pval = 0.99, plot.turn = TRUE, biascorr=FALSE)