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. Author manuscript; available in PMC: 2010 Mar 15.
Published in final edited form as: Multivariate Behav Res. 2009 May;44(3):362–388. doi: 10.1080/00273170902938969

Figure 1.

Figure 1

Graphical illustration of parallel analysis on a simulated data set of 50 observations, across 20 variables, with two uncorrelated factors, and %50 total variance. The dashed line connects unadjusted eigenvalues of the observed data, the dotted line connects mean eigenvalues of 600 random 50*20 data sets, and the solid line connects adjusted eigenvalues (i.e. subtracting the mean eigenvalues minus one from the observed eigenvalues). The retention criterion is the point at which the adjusted eigenvalues cross the horizontal line at y=1, which is the same point at which the unadjusted eigenvalues cross the line of mean eigenvalues of the random data sets. The solid adjusted eigenvalue markers are those components (or factors, if using factor analysis) that are retained.