turfR (version 0.8-7)

turf.args: Arguments used in TURF Analysis

Description

INTERNAL: A list of named arguments that can be passed into turf and turf.combos to control the behavior and output of the TURF algorithm.

Usage

turf.args(depth=1L, keep=0, mc=FALSE, nsims=10000, psims=NULL, sort="d")

Arguments

depth

Scalar indicating depth of reach, see Markowitz (2005). depth is an integer, greater than or equal to 1; non-integer values are coerced using floor(depth).

keep

Scalar indicating the number of combinations of each size to keep in the output object generated by turf. keep is an integer, greater than or equal to zero; non-integer values are coerced using floor(keep). If keep == 0 (default), all combinations evaluated by the TURF algorithm are kept; if keep >= 1, the lesser of keep or the number of evaluated combinations of a given size are kept.

mc

Logical indicating whether or not Monte Carlo simulated subsets of combinations should be substituted for all possible combinations of n choose k or user-specified combinations. When TRUE, subsets are generated using the method described by Adler, et al. (2010), only when nsims is also less than n choose k or the number of user-specified combinations.

nsims

Scalar indicating the number of combination sets of a given size to generate when mc == TRUE. nsims is an integer, greater than or equal to 1; non-integer values are coerced using floor(nsims). This argument is ignored when mc == FALSE.

psims

Vector of length n indicating the probabilities of sampling each item into a combination set when mc == TRUE. Probabilities need not sum to 1 (see sample for additional details). All values must be greater than or equal to 0; for combinations of size k, there must be at least k non-zero values in psims. Default varies depending on calling function; when called from turf, default is the probability of each item being reached; when called from turf.combos, default is rep(1/n, n). psims is ignored when mc == FALSE.

sort

Character indicating sort order of TURF output: "d" (default) causes combinations to be sorted in descending order of reach, then frequency; "a" causes combinations to be sorted in ascending order of reach, then frequency; "n" leaves combinations unsorted (i.e., they remain in the same order as the rows in each element of combos). sort is executed before keep. When sort == "n", keep is ignored (i.e., all combinations evaluated are kept in the output). No other values are permitted.

Value

A list consisting of the named arguments.

Details

Defaults set by this function may be modified by specifying any of the arguments as name-value pairs in place of the (...) argument when calling turf or turf.combos. It is never necessary to call turf.args directly.

References

Adler, T.J., Smith, C. & Dumont, J. 2010. Optimizing product portfolios using discrete choice modeling and TURF. In: S. Hess, A. Daly (Eds), Choice modeling: the state-of-the-art and the state-of-practice; proceedings from the Inaugural International Choice Modeling Conference. Emerald Publishing Group Ltd., pp. 485-497. Krieger, A.M. & Green, P.E. 2000. Turf revisited: Enhancements to toal unduplicated reach and frequency analysis. Marketing Research, 12, 30-36. Markowitz, L. 2005. Going beyond TURF to complement and extend existing product lines. Ipsos-Insight, November 2005. Miaoulis, G., Free, V. & Parsons, H. 1990. TURF: A new planning approach for product line extensions. Marketing Research, March, pp. 28-40.

Examples

  ##INTERNAL USE ONLY