SMOG

This article refers to the acronym. For other uses see smog (disambiguation).

SMOG is a readability formula that estimates the years of education needed to understand a piece of writing. SMOG is widely used, particularly for checking health messages.[1][2] The SMOG formula yields a 0.985 correlation with a standard error of 1.5159 grades with the grades of readers who had 100% comprehension of test materials.[3]

SMOG was published by G. Harry McLaughlin in 1969 as a more accurate and more easily calculated substitute for the Gunning-Fog Index. To make calculating a text's readability as simple as possible an approximate formula was also given — count the words of three or more syllables in three 10-sentence samples, estimate the count's square root (from the nearest perfect square), and add 3.

Numerous online calculators give the SMOG level of submitted text or a URL but only the SMOG Calculator listed below as an external link uses a dictionary to look up the syllable length of words. Because of this, the SMOG Calculator counts syllables more accurately than any other readability program.

In 2010 a study published in the Journal of the Royal College of Physicians of Edinburgh [4] stated that “SMOG should be the preferred measure of readability when evaluating consumer-orientated healthcare material.” The study found that “The Flesch-Kincaid formula significantly underestimated reading difficulty compared with the gold standard SMOG formula.”

Applying SMOG to other languages[5] lacks statistical validity.

Formulae

To calculate SMOG

  1. Count a number of sentences (at least 30)
  2. In those sentences, count the polysyllables (words of 3 or more syllables).
  3. Calculate using
    \mbox{grade} = 1.043 \sqrt{\mbox{number of polysyllables}\times{30 \over \mbox{number of sentences}} } %2B 3.1291

This version (sometimes called the SMOG Index) is more easily used for mental math:

  1. Count the number of polysyllabic words in three samples of ten sentences each.
  2. Take the square root of the nearest perfect square
  3. Add 3

References

  1. ^ Hedman, Amy S. (January 2008). "Using the SMOG formula to revise a health-related document". American Journal of Health Education 39 (1): 61–64. http://www.articlearchives.com/education-training/literacy-illiteracy/880189-1.html. Retrieved 2009-01-19. 
  2. ^ Ley, P.; T. Florio (February 1996). "The use of readability formulas in health care". Psychology, Health & Medicine 1 (1): 7–28. doi:10.1080/13548509608400003. http://www.informaworld.com/smpp/content~db=all~content=a783435805. Retrieved 2010-12-14. 
  3. ^ McLaughlin, G. Harry (May 1969). "SMOG Grading — a New Readability Formula" (PDF). Journal of Reading 12 (8): 639–646. http://webpages.charter.net/ghal/SMOG_Readability_Formula_G._Harry_McLaughlin_(1969).pdf. Retrieved 2008-09-20. 
  4. ^ Fitzsimmons,P.; Michael, B.; Hulley, J.; Scott, G. (2010). "A readability assessment of online Parkinson's disease information". J R Coll Physicians Edinb 40 (4): 292–6. doi:10.4997/JRCPE.2010.401. PMID 21132132. 
  5. ^ Contreras, A.; Garcia-alonso, R.; Echenique, M.; Daye-contreras, F. (1999). "The SOL Formulas for Converting SMOG Readability Scores Between Health Education Materials Written in Spanish, English, and French". Journal of Health Communication 4 (1): 21–29. doi:10.1080/108107399127066. PMID 10977275. http://www.informaworld.com/smpp/content~content=a713851470~db=all. Retrieved 2008-09-20. 

External links