caliperSize function

(Internal) Determines how many other units fall within a caliper distance

The matching functions fullmatch and pairmatch

have a maximum problem size, based on the number of comparisons between treated and control units. For a completely dense problem, in which every treated units is compared to every control unit there are length(treated) * length(control) comparisons. A caliper restricts which comparisons are valid, disallowing matches of treated and control pairs that are too far apart. A caliper can significantly decrease the size of a matching problem. The caliperSize function reports exactly who many valid treated-control comparisons remain after applying a caliper of the given width.

caliperSize(scores, z, width, structure = NULL)

Arguments

• scores: A numeric vector of scores providing 1-D position of units
• z: Treatment indicator vector
• width: Width of caliper, must be positive
• structure: Grouping factor to use in computation

Returns

numeric Total number of pairwise distances remaining after the caliper is placed.