 A statistical graphic designed for the archaeological study of when events of a specified kind occurred.

## Usage

occurrence(object, ...)

# S4 method for EventsMCMC
occurrence(object, interval = c("ci", "hpdi"), level = 0.95)

# S4 method for OccurrenceEvents
autoplot(object, ..., colour = "black")

# S4 method for OccurrenceEvents,missing
plot(x, colour = "black", ...)

## Arguments

object

An EventsMCMC object.

...

Currently not used.

interval

A character string specifying the confidence interval to be drawn. It must be one of "ci" (credible interval; the default) or "hpdi" (highest posterior density interval). Any unambiguous substring can be given.

level

A length-one numeric vector giving the confidence level.

colour

A character string specifying the colour of the segments.

x

An OccurrenceEvents object.

## Value

• occurrence() returns an OccurrenceEvents object.

• autoplot() and multiplot return a ggplot object.

• plot() is called it for its side-effects: it results in a graphic being displayed (invisibly returns x).

An OccurrenceEvents object.

## Details

If we have $$k$$ events, then we can estimate the calendar date $$t$$ corresponding to the smallest date such that the number of events observed before $$t$$ is equal to $$k$$.

The occurrence() estimates these occurrences and gives the credible interval or the highest posterior density (HPD) region for a given level of confidence.

Other event tools: activity(), rec, roc(), tempo()

## Author

A. Philippe, M.-A. Vibet, T. S. Dye, N. Frerebeau

## Examples

## Coerce to MCMC
eve <- as_events(events, calendar = "CE", iteration = 1)
eve <- eve[1:10000, ]

## Occurrence plot
occ_ci <- occurrence(eve, interval = "ci")
plot(occ_ci) occ_hpdi <- occurrence(eve, interval = "hpdi")
plot(occ_hpdi) 