qflag {qmethod}

Q methodology: automatic flagging of Q-sorts

Description

Applies the two standard algorithms to pre-flag Q-sorts automatically, for posterior calculation of the statement scores.

Usage

qflag(loa, nstat)

Arguments

loa

a Q-sort factor loading matrix obtained, for example from
unclass(principal(...)$loadings), or from qmethod(...)$loa.

nstat

number of statements in the study.

Details

These are the two standard criteria for automatic flagging used in Q method analysis:

1. Q-sorts which factor loading is higher than the threshold for p-value < 0.05, and

2. Q-sorts which square loading is higher than the sum of square loadings of the same Q-sort in all other factors.

Returns a logical matrix with Q-sorts as rows, and factors as columns.

The function also runs two checks: Q-sorts flagged that have negative loadings and Q-sorts flagged in more than one factor. If any of these is true, the function returns a warning for the user to inspect the automatic pre-flagging (which should be done in all cases, but particularly in these ones). To conduct manual flagging, see guidelines here: http://aiorazabala.github.io/qmethod/Advanced-analysis

Note

This is a function used within qmethod. Rarely to be used independently.

Author(s)

Aiora Zabala

References

Brown, S. R., 1980 Political subjectivity: Applications of Q methodology in political science, New Haven, CT: Yale University Press.

Van Exel, J., de Graaf, G., Rietveld, P., 2011. "'I can do perfectly well without a car!'" Transportation 38, 383-407 (Page 388, footnote 8).

See further references on the methodology in qmethod-package.

Examples

data(lipset)
library(psych)
loa <- unclass(principal(lipset[[1]], nfactors = 3,
               rotate = "varimax")$loadings)
flagged <- qflag(loa = loa, nstat = nrow(lipset[[1]]))
summary(flagged)

# Remember to manually inspect the automatic pre-flagging:
results=list(loa=loa, flagged=flagged, brief=list(nfactors = ncol(loa)))
loa.and.flags(results)