Point estimates of calibrated radiocarbon dates

Functions for deriving a single point estimate of calendar age from calibrated radiocarbon dates. Note that none of these methods produce a good estimate (Michczyński 2007) , and should only be used as a last resort if the probability distribution function or an interval estimate is not appropriate, in which case cal_mode() (the default) is recommended.

Usage

cal_mode(x, quiet = FALSE)

cal_median(x)

cal_mean(x)

cal_local_mode(x, interval = 0.954)

cal_central(x, interval = 0.954)

Arguments

x

cal object. A vector of calibrated radiocarbon dates.

quiet

Set quiet = TRUE to suppress warnings (only used by cal_mode()).

interval

Numeric. The confidence interval for cal_local_mode() and cal_central(). Default: 0.954.

Value

Numeric vector the same length as x giving the point estimate for each calibrated date.

Details

cal_mode()

Age corresponding to the maximum peak of the probability distribution. If x has more than one modal value, the first is returned.

cal_median()

Age corresponding to the median quantile of the probability distribution.

cal_mean()

Mean age weighted by probability density.

cal_local_mode()

Age corresponding to the maximum peak of the probability distribution within the confidence range specified by interval (not yet implemented).

cal_central()

Age corresponding to the central point of the probability density within the confidence range specified by interval (not yet implemented).

References

Michczyński A (2007). “Is it Possible to Find a Good Point Estimate of a Calibrated Radiocarbon Date?” Radiocarbon, 49(2), 393–401. ISSN 0033-8222, 1945-5755. doi:10.1017/S0033822200042326 .

See also

Other functions for summarising calibrated radiocarbon dates: cal_hdr(), cal_probability()

Examples

x <- c14_calibrate(10000, 30)

cal_mode(x)
#> # cal BP years <yr[1]>:
#> [1] 11400
#> # Era: Before Present (cal BP): Gregorian years (365.2425 days), counted backwards from 1950
cal_median(x)
#> # cal BP years <yr[1]>:
#> [1] 11475
#> # Era: Before Present (cal BP): Gregorian years (365.2425 days), counted backwards from 1950
cal_mean(x)
#> # cal BP years <yr[1]>:
#> [1] 11479.82
#> # Era: Before Present (cal BP): Gregorian years (365.2425 days), counted backwards from 1950