tabula (version 1.6.0)

date_mcd: Mean Ceramic Date

Description

Estimates the Mean Ceramic Date of an assemblage.

Usage

date_mcd(object, dates, ...)
bootstrap_mcd(object, dates, ...)
# S4 method for CountMatrix,numeric
date_mcd(object, dates, errors = NULL, ...)
# S4 method for CountMatrix,numeric
bootstrap_mcd(object, dates, probs = c(0.05, 0.95), n = 1000)

Arguments

object

A '>CountMatrix or a '>DateEvent object.

dates

A numeric vector of dates. If named, the names must match the row names of object.

...

Currently not used.

errors

A numeric vector giving the absolute error of dates.

probs

A numeric vector of probabilities with values in \([0,1]\) (see quantile).

n

A non-negative integer giving the number of bootstrap replications.

Value

date_mcd returns a '>DateMCD object.

bootstrap_mcd returns a data.frame.

Details

The Mean Ceramic Date (MCD) is a point estimate of the occupation of an archaeological site (South 1977). The MCD is estimated as the weighted mean of the date midpoints of the ceramic types (based on absolute dates or the known production interval) found in a given assemblage. The weights are the relative frequencies of the respective types in the assemblage.

A bootstrapping procedure is used to estimate the confidence interval of a given MCD. For each assemblage, a large number of new bootstrap replicates is created, with the same sample size, by resampling the original assemblage with replacement. MCDs are calculated for each replicates and upper and lower boundaries of the confidence interval associated with each MCD are then returned.

References

South, S. A. (1977). Method and Theory in Historical Archaeology. New York: Academic Press.

See Also

Other dating: event

Examples

# NOT RUN {
## Mean Ceramic Date
## Coerce the zuni dataset to an abundance (count) matrix
data("zuni", package = "folio")
counts <- as_count(zuni)

## Set the start and end dates for each ceramic type
dates <- list(
  LINO = c(600, 875), KIAT = c(850, 950), RED = c(900, 1050),
  GALL = c(1025, 1125), ESC = c(1050, 1150), PUBW = c(1050, 1150),
  RES = c(1000, 1200), TULA = c(1175, 1300), PINE = c(1275, 1350),
  PUBR = c(1000, 1200), WING = c(1100, 1200), WIPO = c(1125, 1225),
  SJ = c(1200, 1300), LSJ = c(1250, 1300), SPR = c(1250, 1300),
  PINER = c(1275, 1325), HESH = c(1275, 1450), KWAK = c(1275, 1450)
)

## Calculate date midpoints
mid <- vapply(X = dates, FUN = mean, FUN.VALUE = numeric(1))

## Calculate MCD
mc_dates <- date_mcd(counts, dates = mid)

## Bootstrap resampling
boot <- bootstrap_mcd(counts, dates = mid)
head(boot)
# }