Time Requirements

The FACTOR Procedure

Time Requirements

$n & = & {number of observations} \ v & = & {number of variables} \ f & = & {nu... ...g factor extraction} \ r & = & {length of iterations during factor rotation} \$

The time required to compute...		is roughly proportional to
an overall factor analysis		iv³
the correlation matrix		nv²
PRIORS=SMC or ASMC		v³
PRIORS=MAX		v²
eigenvalues		v³
final eigenvectors		fv²
ROTATE=VARIMAX, QUARTIMAX,
EQUAMAX, ORTHOMAX, PARSIMAX,
PROMAX, or HK		rvf²
ROTATE=PROCRUSTES		vf²

Each iteration in the PRINIT or ALPHA method requires computation of eigenvalues and f eigenvectors.

Each iteration in the ML or ULS method requires computation of eigenvalues and v - f eigenvectors.

The amount of time that PROC FACTOR takes is roughly proportional to the cube of the number of variables. Factoring 100 variables, therefore, takes about 1000 times as long as factoring 10 variables. Iterative methods (PRINIT, ALPHA, ULS, ML) can also take 100 times as long as noniterative methods (PRINCIPAL, IMAGE, HARRIS).

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