Determination of statistical significance of components in principal component analysis using Monte Carlo simulation.

<p>Set 1 (a) and 2 (b) data obtained from mild/moderate and severe autism groups were analyzed with PCA. Scree plots show eigenvalues of raw data (blue), as well as the 50^th (green) and 95^th percentile (yellow) simulated data. A principal component was considered statistically significant (circled in red) whenever its raw data eigenvalue lay above the corresponding 95^th percentile simulated data eigenvalue.