is.friends function

Friends check.

Checks whether a subset of DMUs is friends or not, according to Tone (2010).

is.friends(datadea,
             dmu_eval = NULL,
             dmu_ref = NULL,
             rts = c("crs", "vrs", "nirs", "ndrs"),
             tol = 1e-6)

Arguments

• datadea: The data, including n DMUs, m inputs and s outputs.
• dmu_eval: A numeric vector containing the subset of DMUs to be checked. If NULL (default), all DMUs are considered.
• dmu_ref: A numeric vector containing which DMUs are the evaluation reference set. If NULL (default), all DMUs are considered.
• rts: A string, determining the type of returns to scale, equal to "crs" (constant), "vrs" (variable), "nirs" (non-increasing) or "ndrs" (non-decreasing).
• tol: Numeric, a tolerance margin for checking efficiency. It is 1e-6 by default.

Returns

Returns TRUE if dmu_eval is friends of dmu_ref, and FALSE otherwise.

Examples

data("PFT1981")
datadea <- make_deadata(PFT1981,
                        ni = 5,
                        no = 3)
subset1 <- c(15, 16, 17, 19) # Subset of DMUs to be checked
result1 <- is.friends(datadea = datadea,
                      dmu_eval = subset1,
                      dmu_ref = 1:20) # We only consider a cluster formed by the first 20 DMUs
subset2 <- c(15, 16, 17, 20) # Another subset of DMUs to be checked
result2 <- is.friends(datadea = datadea,
                      dmu_eval = subset2,
                      dmu_ref = 1:20) # We only consider a cluster formed by the first 20 DMUs

References

Tone, K. (2010). "Variations on the theme of slacks-based measure of efficiency in DEA", European Journal of Operational Research, 200, 901-907. tools:::Rd_expr_doi("10.1016/j.ejor.2009.01.027")

See Also

maximal_friends, model_sbmeff

Author(s)

Vicente Coll-Serrano (vicente.coll@uv.es ). Quantitative Methods for Measuring Culture (MC2). Applied Economics.

Vicente Bolós (vicente.bolos@uv.es ). Department of Business Mathematics

Rafael Benítez (rafael.suarez@uv.es ). Department of Business Mathematics

University of Valencia (Spain)