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FACTOR { VARIABLES=var_list, MATRIX IN ({CORR,COV}={*,file_spec}) } [ /METHOD = {CORRELATION, COVARIANCE} ] [ /ANALYSIS=var_list ] [ /EXTRACTION={PC, PAF}] [ /ROTATION={VARIMAX, EQUAMAX, QUARTIMAX, PROMAX[(k)], NOROTATE}] [ /PRINT=[INITIAL] [EXTRACTION] [ROTATION] [UNIVARIATE] [CORRELATION] [COVARIANCE] [DET] [KMO] [AIC] [SIG] [ALL] [DEFAULT] ] [ /PLOT=[EIGEN] ] [ /FORMAT=[SORT] [BLANK(n)] [DEFAULT] ] [ /CRITERIA=[FACTORS(n)] [MINEIGEN(l)] [ITERATE(m)] [ECONVERGE (delta)] [DEFAULT] ] [ /MISSING=[{LISTWISE, PAIRWISE}] [{INCLUDE, EXCLUDE}] ]
The FACTOR
command performs Factor Analysis or Principal Axis Factoring on a dataset. It may be used to find
common factors in the data or for data reduction purposes.
The VARIABLES
subcommand is required (unless the MATRIX IN
subcommand is used).
It lists the variables which are to partake in the analysis. (The ANALYSIS
subcommand may optionally further limit the variables that
participate; it is useful primarily in conjunction with MATRIX IN
.)
If MATRIX IN
instead of VARIABLES
is specified, then the analysis
is performed on a pre-prepared correlation or covariance matrix file instead of on
individual data cases. Typically the matrix file will have been generated by
MATRIX DATA
(see MATRIX DATA) or provided by a third party.
If specified, MATRIX IN
must be followed by ‘COV’ or ‘CORR’,
then by ‘=’ and file_spec all in parentheses.
file_spec may either be an asterisk, which indicates the currently loaded
dataset, or it may be a filename to be loaded. See MATRIX DATA, for the expected
format of the file.
The /EXTRACTION
subcommand is used to specify the way in which factors (components) are extracted from the data.
If PC
is specified, then Principal Components Analysis is used.
If PAF
is specified, then Principal Axis Factoring is
used. By default Principal Components Analysis will be used.
The /ROTATION
subcommand is used to specify the method by which the extracted solution will be rotated.
Three orthogonal rotation methods are available:
VARIMAX
(which is the default), EQUAMAX
, and QUARTIMAX
.
There is one oblique rotation method, viz: PROMAX
.
Optionally you may enter the power of the promax rotation k, which must be enclosed in parentheses.
The default value of k is 5.
If you don’t want any rotation to be performed, the word NOROTATE
will prevent the command from performing any
rotation on the data.
The /METHOD
subcommand should be used to determine whether the covariance matrix or the correlation matrix of the data is
to be analysed. By default, the correlation matrix is analysed.
The /PRINT
subcommand may be used to select which features of the analysis are reported:
UNIVARIATE
A table of mean values, standard deviations and total weights are printed.
INITIAL
Initial communalities and eigenvalues are printed.
EXTRACTION
Extracted communalities and eigenvalues are printed.
ROTATION
Rotated communalities and eigenvalues are printed.
CORRELATION
The correlation matrix is printed.
COVARIANCE
The covariance matrix is printed.
DET
The determinant of the correlation or covariance matrix is printed.
AIC
The anti-image covariance and anti-image correlation matrices are printed.
KMO
The Kaiser-Meyer-Olkin measure of sampling adequacy and the Bartlett test of sphericity is printed.
SIG
The significance of the elements of correlation matrix is printed.
ALL
All of the above are printed.
DEFAULT
Identical to INITIAL
and EXTRACTION
.
If /PLOT=EIGEN
is given, then a “Scree” plot of the eigenvalues will be printed. This can be useful for visualizing
which factors (components) should be retained.
The /FORMAT
subcommand determined how data are to be displayed in loading matrices. If SORT
is specified, then the variables
are sorted in descending order of significance. If BLANK(n)
is specified, then coefficients whose absolute value is less
than n will not be printed. If the keyword DEFAULT
is given, or if no /FORMAT
subcommand is given, then no sorting is
performed, and all coefficients will be printed.
The /CRITERIA
subcommand is used to specify how the number of extracted factors (components) are chosen.
If FACTORS(n)
is
specified, where n is an integer, then n factors will be extracted. Otherwise, the MINEIGEN
setting will
be used.
MINEIGEN(l)
requests that all factors whose eigenvalues are greater than or equal to l are extracted.
The default value of l is 1.
The ECONVERGE
setting has effect only when iterative algorithms for factor
extraction (such as Principal Axis Factoring) are used.
ECONVERGE(delta)
specifies that
iteration should cease when
the maximum absolute value of the communality estimate between one iteration and the previous is less than delta. The
default value of delta is 0.001.
The ITERATE(m)
may appear any number of times and is used for two different purposes.
It is used to set the maximum number of iterations (m) for convergence and also to set the maximum number of iterations
for rotation.
Whether it affects convergence or rotation depends upon which subcommand follows the ITERATE
subcommand.
If EXTRACTION
follows, it affects convergence.
If ROTATION
follows, it affects rotation.
If neither ROTATION
nor EXTRACTION
follow a ITERATE
subcommand it will be ignored.
The default value of m is 25.
The MISSING
subcommand determines the handling of missing variables.
If INCLUDE
is set, then user-missing values are included in the
calculations, but system-missing values are not.
If EXCLUDE
is set, which is the default, user-missing
values are excluded as well as system-missing values.
This is the default.
If LISTWISE
is set, then the entire case is excluded from analysis
whenever any variable specified in the VARIABLES
subcommand
contains a missing value.
If PAIRWISE
is set, then a case is considered missing only if either of the
values for the particular coefficient are missing.
The default is LISTWISE
.
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