# Analysis of Spatial Gradients in Radiocarbon Dates

## Documentation for package ‘spDates’ version 1.1

- DESCRIPTION file.

## Help Pages

centers | Coordinates of 9 sites considered as potential centers of origin of the Neolithic expansion. Modified from Pinhasi et al. (2005).
filterDates | Filter archaeological site coordinates and dates, retaining only the earliest radiocarbon date per site.
interpolateIDW | Interpolate using inverse distance weighting.
iterateSites | Perform regression of dates versus distances from multiple potential origins in order to find the best model. It is also possible to specify multiple distances for the spatial binning of the dates.
land | Land polygons.

modelDates

Perform regression of archaeological dates on great circle distances from a hypothetical origin. Dates can be filtered to retain only the earliest dates per distance bins (Hamilton and Buchanan 2007). Bootstrap is executed to account for uncertainty in calibrated dates. Regression can be either reduced major axis or ordinary least squares. If using ordinary least squares, regression is performed both on time-versus-distance and on distance-versus-time.

neof | Radiocarbon dates and coordinates of 717 Neolithic sites in the Near East and Europe. Modified from Pinhasi et al. (2005). Only the earliest dates per site are included.
plot.dateMap | Plot a map with the results of the iteration over multiple sites, showing an interpolated surface of r values for the sites considered as potential origins.
plot.dateModel | Plot the results of the regression bootstrap on archaeological dates versus distances from a hypothetical origin, with fitted lines.
sampleCalDates | Extract a single year estimate for ranges of calibrated dates with a probability given by the calibrated probability distribution.
summary.dateModel | Return summary statistics for a dateModel object.