Predicting midsagittal pharyngeal dimensions from measures of anterior tongue position in Swedish vowels: Statistical considerations

In a re-analysis of x rays of speakers producing Swedish vowels, midsagittal pharyngeal dimensions were predicted from anterior tongue positions using procedures based on estimated tongue pellet positions. Principal component analysis was used to reduce the number of pellet degrees of freedom from eight to three prior to applying linear regression from these three independent variables to dependent vocal tract midsagittal cross distances. Except for the regions around the laryngopharynx and uvula, the pharynx dimensions were predictable from linear regressions and were significant at the p<0.05 level. Numerical experiments show that it is crucial to reduce the number of independent variables in tests of statistical significance.