Six Sigma Tool Navigator: The Master Guide for Teams

Tool description

Developed by Robert Gunning, the fog index stands for the reading level required to understand written information. Computing the fog index allows a writer to assess at what reading level he or she is currently writing and what adjustments, if any, are needed to write for a particular audience.

Typical application

• To determine a reading level requirement for one's writing.

• To estimate an educational level needed to understand written information.

Problem-solving phase

Typically used by

before

• Audience analysis

• Surveying

• Questionnaires

• Cluster analysis

• Starbursting

after

• Thematic content analysis

• Case study

• Critical incident

• Presentation

• Storyboarding

Notes and key points

• Calculating Robert Gunning's Fog Index:

  F.I. = 0.4 (A + B)

  Where:	.4	=	A constant
  	A	=	Average number of words per sentence
  	B	=	Number of words with three or more syllables

Step-by-step procedure

• STEP 1 Take a random sample of 100 to 200 words of written material.

• STEP 2 Count the number of sentences found in the sample.

  Note

  Independent clauses are counted as sentences.

• STEP 3 Divide the total number of words in the sample by the number of sentences. This will result in the average number of words per sentence. See example Using these Written Process Steps.

• STEP 4 Identify and count the number of words having three or more syllables.

  Note

  Exclude words that may qualify because of -es, -ed, -ing, or words that are capitalized or compounded.

• STEP 5 Add the totals of Step 3 and Step 4 above and multiply the total by 0.4 to get the fog index. This result identifies the level of reading ability one should have to understand these written process steps.

Example of tool application

Using These Written Process Steps