. Author manuscript; available in PMC: 2022 Feb 1.

Published in final edited form as: Clin Neuropsychol. 2020 Apr 1;35(2):293–307. doi: 10.1080/13854046.2020.1723707

Table 8.

Calculation of the Processing Speed Index (PSI)

Measure	Equation

Age-adjusted PSI	$15 \times (\frac{[A g e - a d j u s t e d S t d . S c r . D i g i t S y m b o l T o t a l C o r r e c t + A g e - a d j u s t e d S S S y m b o l S e a r c h T o t a l C o r r e c t] - 199.9639}{27.53168}) + 100$
PSI T-Score	$15 \times (\frac{A g e - c o r r e c t e d P S I - (69.149897 + 14.324006 * \frac{a g e}{100} + 37.586054 * {(\frac{e d u + 1}{10})}^{2} - 14.247762 * {(\frac{e d u + 1}{10})}^{3} - 2.443968 * g e n d e r)}{10.22894}) + 100$

Note. These formulas should be applied to education ranges of 0–20 years and age 19–60 years. Using values outside these ranges might result in extrapolation errors. Std.Scr.: Standard Score (based on equations in Table 5); Gender: Male=1; Female=0; Edu: years of education; Age: years of age