NCA: Necessary Condition Analysis

Performs a Necessary Condition Analysis (NCA). (Dul, J. 2016. Necessary Condition Analysis (NCA). ”Logic and Methodology of 'Necessary but not Sufficient' causality." Organizational Research Methods 19(1), 10-52) NCA identifies necessary (but not sufficient) conditions in datasets. Instead of drawing a regression line ”through the middle of the data” in an xy-plot, NCA draws the ceiling line. The ceiling line y = f(x) separates the area with observations from the area without observations. (Nearly) all observations are below the ceiling line: y <= f(x). The empty zone is in the upper left hand corner of the xy-plot (with the convention that the x-axis is ”horizontal” and the y-axis is ”vertical” and that values increase ”upwards” and ”to the right”). The ceiling line is a (piecewise) linear non-decreasing line: a linear step function or a straight line. It indicates which level of x (e.g. an effort or input) is necessary but not sufficient for a (desired) level of y (e.g. good performance or output).

Version: 2.0
Imports: gplots, quantreg, sfa, KernSmooth
Suggests: testthat
Published: 2016-05-18
Author: Jan Dul
Maintainer: Govert Buijs <buijs at>
License: GPL (≥ 3)
NeedsCompilation: no
CRAN checks: NCA results


Reference manual: NCA.pdf
Package source: NCA_2.0.tar.gz
Windows binaries: r-devel:, r-release:, r-oldrel:
OS X El Capitan binaries: r-release: NCA_2.0.tgz
OS X Mavericks binaries: r-oldrel: NCA_2.0.tgz
Old sources: NCA archive


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