QCAtools (version 0.2.3)

consistency: Compute the consistency value

Description

Computes the consistency score of "formula1 -> formula2" (sufficient condition) or "formula1 <- formula2" (necessary condition), depending on whether type is "->" or "<-". If type is "<->" it computes an equivalence score of formula1 and formula2 via the formula sum(min(X,Y))/(sum(max(X,Y))

Usage

consistency(formula1, type = "->", formula2, data)

Arguments

formula1

A string, list of strings or function representing a Boolean formula in disjunctive normal form

type

either "->", "<-" or "<->", depending on the direction of the implication that is to be evaluated

formula2

A string, list of strings or function representing a Boolean formula in disjunctive normal form

data

A data frame where the rows represent cases and the columns the sets. Column names must be as in the formula.

Value

the consistency score of the implication described by formula1, type and formula2

Details

Compute a consistency score for an implication/necessity/sufficiency statement.

If formula is a function, it must take a data.frame and return a vector.

If formula is a string or list of strings, the following conventions hold: Set names must be capitalized in the formula and the data; if they are lowercase, they are interpreted as the negation of the set. If formula is a string, logical 'or' is expressed as a '+', and logical 'and' as a '*'. If formula is a list of strings, the strings are assumed to be the dosjuncts and are concatenated with '+'. The formula must be in disjunctive normal form, i.e. it must be a disjunction of conjunctions of elementary or negated elementary sets. Example: A*b*C + a*B

Examples

require(QCA)
data(d.urban)
consistency("MLC + FRB", "->", "CP", d.urban)