paleofire (version 1.2.4)

pfCircular: Circular block bootstrap procedure applied to charcoal records compositing results

Description

Block bootstrap has been proposed to test the significances of changes in stationary time series (Kunsch 1989). This procedure consists of splitting each charcoal series into n-b+1 overlapping blocks of data, where n is sample size and b the block size. These blocks are used to reconstruct resampled individual charcoal series that are in turn used to estimate the confidence intervals around the charcoal series composite mean.

Usage

pfCircular(comp, b = NULL, conf = c(0.05, 0.95), nboot = 1000, AgeLim = NULL)

Arguments

comp

A "pfComposite" object

b

A numeric giving block size, if NULL the optimal block size for a given series is given by: b= 2x(-1 /log(p)), where p is the lag one autocorrelation coefficient of that series (Adams, Mann & Ammann 2003).

conf

Numeric, calculated confidence intervals.

nboot

Numeric, number of bootstrap replicates.

AgeLim

Numeric, years defining a period to restrict the analysis to.

Value

out

A "pfCircular" object with estimated confidence intervals.

References

Kunsch, H. R. 1989. The jackknife and the bootstrap for general stationary observation s. The Annals of Statistics 17:1217-1241.

Adams, J. B., M. E. Mann, and C. M. Ammann. 2003. Proxy evidence for an El Nino-like response to volcanic forcing. Nature 426:274-278.

Examples

# NOT RUN {
ID=pfSiteSel(lat>49, lat<75, long>6, long<50)
plot(ID,zoom="world")
TR1=pfTransform(ID, method=c("MinMax","Box-Cox","Z-Score"),BasePeriod=c(200,2000))

## Circular block bootstrapp

COMP=pfComposite(TR1, binning=TRUE, bins=seq(0,2000,100))
circ=pfCircular(COMP,conf=c(0.005,0.025,0.975,0.995),nboot=100)
plot(circ)
# }