Calibrate a Single Radiocarbon Determination

Uses the supplied calibration curve to calibrate a single radiocarbon determination and uncertainty (expressed either in terms of radiocarbon age, or as an F\({}^{14}\)C concentration) and obtain its calendar age probability density estimate.

Usage

CalibrateSingleDetermination(
  rc_determination,
  rc_sigma,
  calibration_curve,
  F14C_inputs = FALSE,
  resolution = 1,
  plot_output = FALSE,
  plot_cal_age_scale = "BP",
  interval_width = "2sigma",
  bespoke_probability = NA,
  denscale = 3,
  plot_pretty = TRUE
)

Arguments

rc_determination

A single observed radiocarbon determination provided either as the radiocarbon age (in \({}^{14}\)C yr BP) or the F\({}^{14}\)C concentration.

rc_sigma

The corresponding measurement uncertainty of the radiocarbon determination (must be in the same units as above, i.e., reported as \({}^{14}\)C age or F\({}^{14}\)C)

calibration_curve

A dataframe which must contain one column calendar_age_BP, and also columns c14_age and c14_sig or f14c and f14c_sig (or both sets). This format matches the curves supplied with this package, e.g., intcal20, intcal13, which contain all 5 columns.

F14C_inputs

TRUE if the provided rc_determination is an F\({}^{14}\)C concentration and FALSE if it is a radiocarbon age. Defaults to FALSE.

resolution

The distance between the calendar ages at which to calculate the calendar age probability. Default is 1.

plot_output

TRUE if you wish to plot the determination, the calibration curve, and the posterior calibrated age estimate on the same plot. Defaults to FALSE

plot_cal_age_scale

Only for usage when plot_output = TRUE. The calendar scale to use for the x-axis. Allowed values are "BP", "AD" and "BC". The default is "BP", corresponding to plotting in cal yr BP.

interval_width

Only for usage when plot_output = TRUE. The confidence intervals to show for the calibration curve and for the highest posterior density ranges. Choose from one of "1sigma" (68.3%), "2sigma" (95.4%) and "bespoke". Default is "2sigma".

bespoke_probability

The probability to use for the confidence interval if "bespoke" is chosen above. E.g. if 0.95 is chosen, then the 95% confidence interval is calculated. Ignored if "bespoke" is not chosen.

denscale

Whether to scale the vertical range of the calendar age density plot relative to the calibration curve plot (optional). Default is 3 which means that the maximum calendar age density will be at 1/3 of the height of the plot.

plot_pretty

logical, defaulting to TRUE. If set TRUE then will select pretty plotting margins (that create sufficient space for axis titles and rotates y-axis labels). If FALSE will implement current user values.

Value

A data frame with one column calendar_age_BP containing the calendar ages, and the other column probability containing the probability at that calendar age.

Examples

# Calibration of a single determination expressed as 14C age BP
calib <- CalibrateSingleDetermination(860, 35, intcal20)
plot(calib, type = "l", xlim = c(1000, 600))


# Incorporating an automated plot to visualise the calibration
CalibrateSingleDetermination(860, 35, intcal20, plot_output = TRUE)


# Calibration of a single (old) determination expressed as 14C age BP
calib <- CalibrateSingleDetermination(31020, 100, intcal20)
plot(calib, type = "l", xlim = c(36500, 34500))


# Calibration of a single (old) determination expressed as F14C concentration
calib <- CalibrateSingleDetermination(
    0.02103493, 0.0002618564, intcal20, F14C_inputs = TRUE)
plot(calib, type = "l", xlim = c(36500, 34500))


# Calibration of a single determination expressed as 14C age BP
# against SHCal20 (and creating an automated plot)
CalibrateSingleDetermination(1413, 25, shcal20, plot_output = TRUE)


# Implementing a bespoke confidence interval level and plot in AD
CalibrateSingleDetermination(
    1413,
    25,
    shcal20,
    plot_output = TRUE,
    plot_cal_age_scale = "AD",
    interval_width = "bespoke",
    bespoke_probability = 0.8)


# Changing denscale (so the calendar age density takes up less space)
CalibrateSingleDetermination(
    1413,
    25,
    shcal20,
    plot_output = TRUE,
    interval_width = "bespoke",
    bespoke_probability = 0.8,
    denscale = 5)