Get or set growth rates of a tis time series in annual
percent terms.
growth.rate(x, lag = 1, simple = T)
growth.rate(x, start = end(x) + 1, simple = T) <- valuea tis time series or something that can be turned into
one by as.tis
number of lags to use in calculating the growth rate as outlined in the details below
simple growth rates if TRUE, compound growth
rates if FALSE
the first ti time index for which values of
x should be replaced to make growth.rate(x[start]) == value[1].
desired growth rates
growth.rate(x) returns a tis series of growth rates in
annual percentage terms.
Beginning with the observation indexed by start,
growth.rate(x) <- value
sets the values of x such that the growth rates in annual
percentage terms will be equal to value. x is extended
if necessary. The modified x is invisibly returned.
An example: Suppose x is a quarterly series, then if simple is
TRUE,
growth.rate(x, lag = 3) == 100 * ((x[t]/x[t-3]) - 1) * (4/3)
while if simple is FALSE
growth.rate(x, lag = 3) == 100 * ((x[t]/x[t-3])^(4/3) - 1).