Table 1 Instruments and calculations used to assess readability

FRE

FRE = 206.835 − (84.6 × \( \frac{syllables}{words} \)) − (1.015 × \( \frac{words}{sentences} \))

FKG

FKG = (11.8 × \( \frac{syllables}{words} \)) + (0.39 × \( \frac{words}{sentences} \)) − 15.59

GFI

GFI = 0.4 × [(\( \frac{words}{sentences} \)) + (\( \frac{\sigma }{words} \) × 100)]

σ=number of words with greater than or equal to 3 syllables

CLI

CLI = (0.0588 × γ) − (0.296 × ω) − 15.8

γ=average number of letters per 100 words

ω=average number of sentences per 100 words

SMOG

SMOG

= 1.0430 × \( \sqrt{\sigma \times \frac{30}{number\ of\ sentences}} \) +  3.1291

σ=number of words greater than or equal to 3 syllables

ARI

ARI = (4.17× \( \frac{characters}{words} \)) + (0.5 × \( \frac{words}{sentences} \)) − 21.43