| efa_scores | R Documentation |
Computes factor-score weights, and (from raw data) the factor scores
themselves, for an efa_fit() solution or a directly supplied loading matrix.
It also returns score-quality diagnostics: the score intercorrelations, the
determinacy (validity) and univocality of each score, and Guttman's
indeterminacy index. Factor scores are returned only when raw data are
supplied; a correlation matrix yields the weights and diagnostics alone.
efa_scores(
x,
f,
Phi = NULL,
rho = NULL,
method = c("regression", "Bartlett", "Anderson", "tenBerge", "Harman", "components")
)
x |
data.frame or matrix. Raw data (needed to obtain factor scores) or a
correlation matrix (yields weights and diagnostics only). When Raw data are scored as supplied: no imputation is performed, so a case with a
missing value on any model variable receives |
f |
object of class |
Phi |
matrix. Factor intercorrelations. Only used when a loading matrix is
supplied directly in |
rho |
matrix. Correlation matrix used to derive the scoring weights.
Defaults to |
method |
character. The factor-score method: one of |
Each method combines the loadings with some or all of the factor correlations and the scoring correlation matrix into weights in a different way:
"regression"Thurstone's (1935) regression scores.
"Bartlett"Bartlett's (1937) scores.
"Anderson"Anderson & Rubin's (1956) scores.
"tenBerge"ten Berge, Krijnen, Wansbeek & Shapiro's (1999) scores.
"Harman"Harman's (1976) scores, based on an idealized variable (a hypothetical variable that would correlate perfectly with the factor).
"components"Component scores. These are formed from the raw,
uncentered data (X %*% W) rather than the standardized data, so unlike
the other methods they are on the scale of the input variables. The
diagnostics below describe the standardized combination scale(X) %*% W,
and therefore differ from the realized correlations of the returned scores
whenever the variables have unequal variances.
The determinacy (validity) of a score is its correlation with the factor it
estimates, computed from the returned weights; for regression scores it is the
multiple correlation between the factor and the observed variables (Guttman,
1955; Grice, 2001). The off-diagonal score-factor correlations give the
univocality (the correlation of a score with the other factors). Guttman's
(1955) indeterminacy index, 2 rho^2 - 1, is the minimum correlation between
two equally valid sets of scores. For a method other than "regression"
both quantities are specific to those scores: the determinacy is the method's
own score-factor correlation (never larger than the regression value), and
the reported guttman follows from it.
Determinacies close to 1 mean the scores stand in for the factor with little
loss; Grice (2001) regards values of about .90 and above as the level required
before scores are interpreted for individual cases, and treats lower values as
usable only for group-level research. The Guttman index makes the same point
more sharply, because a factor score is never the factor: at rho = .90 two
equally valid sets of scores can still correlate as low as .62, and at
rho = .80 as low as .28, so the rank order of cases is not unique.
Which method to prefer follows from what the scores are for. Regression
scores correlate most highly with the factor, but they are biased towards it
and correlate across factors even when the model is orthogonal. Bartlett
scores are conditionally unbiased, which makes them the choice when the scores
stand in for the factor in a later model. "tenBerge" reproduces the factor
intercorrelations Phi, so it is the choice when the scores will be correlated
with each other or with external variables. "Anderson" forces the scores to
be uncorrelated with unit variance and is appropriate only when the factors
themselves are orthogonal. "components" is a weighted sum of the observed
variables rather than an estimate of a common factor.
An object of class efa_scores, a list containing:
weights |
The |
scores |
The factor scores ( |
r.scores |
The |
score_cor |
The |
determinacy |
A data frame with, per factor, the determinacy |
settings |
A list of the settings used, including the number of supplied
observations |
Thurstone, L. L. (1935). The vectors of mind. University of Chicago Press.
Bartlett, M. S. (1937). The statistical conception of mental factors. British Journal of Psychology, 28, 97-104.
Anderson, T. W., & Rubin, H. (1956). Statistical inference in factor analysis. In Proceedings of the Third Berkeley Symposium on Mathematical Statistics and Probability (Vol. 5, pp. 111-150). University of California Press.
Guttman, L. (1955). The determinacy of factor score matrices with implications for five other basic problems of common-factor theory. British Journal of Statistical Psychology, 8, 65-81.
ten Berge, J. M. F., Krijnen, W. P., Wansbeek, T., & Shapiro, A. (1999). Some new results on correlation-preserving factor scores prediction methods. Linear Algebra and its Applications, 289, 311-318.
Grice, J. W. (2001). Computing and evaluating factor scores. Psychological Methods, 6, 430-450.
efa_fit() for the solution these are computed from.
Other factor scoring:
print.efa_scores()
# Weights and score diagnostics from an EFA on a correlation matrix
efa <- efa_fit(test_models$baseline$cormat, n_factors = 3, N = 500,
estimator = "PAF", rotation = "oblimin")
fs <- efa_scores(test_models$baseline$cormat, f = efa)
fs
summary(fs)
# Factor scores from raw data (Bartlett method)
efa_raw <- efa_fit(GRiPS_raw, n_factors = 1, estimator = "PAF")
efa_scores(GRiPS_raw, f = efa_raw, method = "Bartlett")
# Loadings supplied directly, with the factor intercorrelations
efa_scores(test_models$baseline$cormat, f = efa$rot_loadings, Phi = efa$Phi)
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