mix_moment | R Documentation |
Conditional moments of MixAR models.
mix_location(model, x, index, xcond) mix_variance(model, x, index, xcond) mix_central_moment(model, x, index, xcond, k) mix_moment(model, x, index, xcond, k) mix_kurtosis(...) mix_ekurtosis(...)
model |
a MixAR object. |
x |
a time series. |
index |
a vector of indices in |
xcond |
a time series, the point prediction is computed for the
first value after the end of the time series. Only the last
|
k |
a positive integer specifying the moment to compute. |
... |
passed on to |
These functions compute conditional moments and related quantities.
kurtosis
and ekurtosis
compute conditional kurtosis and
excess kurtosis, respectively. Effectively, they have the same
parameters as mix_central_moment
, since they pass "..."
to it along with k = 4
. It is an error to supply argument
k
to the kurtosis functions.
when called with one argument (model
), a function with argument xcond
;
otherwise if xcond
is not missing, a single numeric value;
otherwise a vector of length length(index)
.
I wrote the above description recently from reading six years old code, it may need further verification.
Georgi N. Boshnakov
boshnakov2009marmixAR
mix_pdf
, mix_cdf
, mix_qf
for the predictive distributions (pdf, cdf, quantiles);
## data(ibmclose, package = "fma") # `ibmclose' ibmclose <- as.numeric(fma::ibmclose) length(ibmclose) # 369 max(exampleModels$WL_ibm@order) # 2 ## compute point predictions for t = 3,...,369 pred <- mix_location(exampleModels$WL_ibm, ibmclose) plot(pred) ## compute one-step point predictions for t = 360,...369 mix_location(exampleModels$WL_ibm, ibmclose, index = 369 - 9:0 ) f <- mix_location(exampleModels$WL_ibm) # a function ## predict the value after the last f(ibmclose) ## a different way to compute one-step point predictions for t = 360,...369 sapply(369 - 10:1, function(k) f(ibmclose[1:k])) ## the results are the same, but notice that xcond gives past values ## while index above specifies the times for which to compute the predictions. identical(sapply(369 - 10:1, function(k) f(ibmclose[1:k])), mix_location(exampleModels$WL_ibm, ibmclose, index = 369 - 9:0 )) ## conditional variance f <- mix_variance(exampleModels$WL_ibm) # a function ## predict the value after the last f(ibmclose) ## a different way to compute one-step point predictions for t = 360,...369 sapply(369 - 10:1, function(k) f(ibmclose[1:k])) ## the results are the same, but notice that xcond gives past values ## while index above specifies the times for which to compute the predictions. identical(sapply(369 - 10:1, function(k) f(ibmclose[1:k])), mix_variance(exampleModels$WL_ibm, ibmclose, index = 369 - 9:0 )) # interesting example # bimodal distribution, low kurtosis, 4th moment not much larger than 2nd moWL <- exampleModels$WL_ibm mix_location(moWL,xcond = c(500,450)) mix_kurtosis(moWL,xcond = c(500,450)) f1pdf <- mix_pdf(moWL,xcond = c(500,450)) f1cdf <- mix_cdf(moWL,xcond = c(500,450)) gbutils::plotpdf(f1pdf,cdf=f1cdf) gbutils::plotpdf(f1cdf,cdf=f1cdf) f1cdf(c(400,480)) mix_variance(moWL,xcond = c(500,450)) mix_central_moment(moWL,xcond = c(500,450), k=2) sqrt(mix_variance(moWL,xcond = c(500,450))) sqrt(mix_central_moment(moWL,xcond = c(500,450), k=2))
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