coreInfluence function

Find the influence of dates in a pair of Bchronology runs across the core

This function takes as input two Bchronology runs and compares the uncertainty intervals. It does this by computing the mean uncertainty across the core (type = 'mean') at a specified percentile level (e.g. 95%) and subsequently reporting the reduction/increase in uncertainty between the two runs. Both cores must have the same set of depths/positions at regular intervals.

coreInfluence(
  bchrRun1,
  bchrRun2,
  percentile = 0.95,
  type = c("plot", "summary", "max"),
  ageTolerance = 500,
  ...
)

Arguments

• bchrRun1: The output of a run of the Bchronology function
• bchrRun2: The output of another run of the Bchronology function, possibly with different dates. Note this must have the same value of predictPositions as bchrRun1
• percentile: The value of the percentile to compare the uncertainties. Default is 95%
• type: if plot will return a plot of the difference in uncertainties at the specified percentile level. If summary will return text output of the reduction in uncertainty at each position. If max will return the position of the maximum decrease in uncertainty and a list of all the positions where the reduction in uncertainty exceeds the value of ageTolerance
• ageTolerance: A value in years for which to report the positions at which the reduction in uncertainty exceeds this value.
• ...: Additional arguments to plot

Returns

Depending on type will outputs some text and plots providing the influence values for the cores in question.

Details

For example, if the ageTolerance value is 500 years, then coreInfluence will return all of the positions at which the uncertainty reduction is bigger than 500.

Examples

data(Glendalough)
# Start with a run that remove two dates
GlenOut1 <- Bchronology(
  ages = Glendalough$ages[-c(3:4)],
  ageSds = Glendalough$ageSds[-c(3:4)],
  calCurves = Glendalough$calCurves[-c(3:4)],
  positions = Glendalough$position[-c(3:4)],
  positionThicknesses = Glendalough$thickness[-c(3:4)],
  ids = Glendalough$id[-c(3:4)],
  predictPositions = seq(0, 1500, by = 10)
)
GlenOut2 <- Bchronology(
  ages = Glendalough$ages,
  ageSds = Glendalough$ageSds,
  calCurves = Glendalough$calCurves,
  positions = Glendalough$position,
  positionThicknesses = Glendalough$thickness,
  ids = Glendalough$id,
  predictPositions = seq(0, 1500, by = 10)
)

# Now compare their influence
coreInfluence(GlenOut1,
  GlenOut2,
  type = c("max", "plot"),
  xlab = "Age (cal years BP)",
  ylab = "Depth (cm)",
  main = "Chronology difference at 95% for
              Glendalough removing two dates",
  las = 1
)

See Also

Bchronology, choosePositions, dateInfluence for finding the influence of removing a single date from a core