Estimates the Mean Ceramic Date of an assemblage.

date_mcd(object, dates, ...)

# S4 method for CountMatrix,numeric
date_mcd(object, dates, errors = NULL, level = 0.95, n = 1000, ...)

## Arguments

object A CountMatrix or a DateModel object. A numeric vector of dates. If named, the names must match the row names of object. Currently not used. A numeric vector giving the absolute error of dates. A length-one numeric vector giving the confidence level. A non-negative integer giving the number of bootstrap replications.

## Value

date_mcd returns a data.frame with the following columns:

id

An identifier to link each row to an assemblage.

date

The Mean Ceramic Date.

error

The error on the MCD.

lower

The lower boundary of the confidence interval.

upper

The upper boundary of the confidence interval.

## 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. Confidence interval are not estimated for assemblages with only a single type (NAs are returned).

## References

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

Other dating: event

N. Frerebeau

## Examples

## Mean Ceramic Date
## Coerce the zuni dataset to an abundance (count) matrix
zuni_counts <- as_count(zuni)
## Set the start and end dates for each ceramic type
zuni_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
zuni_mid <- vapply(X = zuni_dates, FUN = mean, FUN.VALUE = numeric(1))

## Calculate MCD
## (we use a bootstrapping procedure to estimate the confidence interval)
zuni_mcd <- date_mcd(zuni_counts, dates = zuni_mid)
utils::vignette("dating", package = "tabula")#> Warning: vignette ‘dating’ not found# }