The FORCAST Readability Formula for Technical & Advanced Texts

FORCAST Readability Formula is the only formula not designed for running narrative or connected text. It counts syllables instead of familiar words and ignores sentence length. This focus makes it best for texts that don’t have full sentence stops or the usual paragraph format. Therefore, you can apply it on multiple-choice quizzes, applications, instructional texts, entrance forms, technical manuals, and so on. FORCAST can score texts above primary age reading materials, from 5th grade to college. (You can score your text using our free FORCAST Readability Calculator.)

The making of FORCAST is historically noteworthy. In the early 1970s, as the draft called thousands to serve during the Vietnam War, the U.S. Army faced a literacy challenge: many fresh-faced recruits struggled with basic reading. Military manuals and directives might as well have been written in code. It was an issue that, if ignored, threatened to weaken the very fabric of the military’s operations.

The Human Resources Research Organization assigned linguists J. Patrick Ford, John S. Caylor, and Thomas G. Sticht to study the reading guidelines of military occupational specialties (MOS). Their subjects were Vietnam draftees entering basic training and job-specific military roles. The FORCAST (FORd, CAylor, STicht) formula evolved from their research. The formula, first announced in 1973, could assess how complex reading materials were for different military roles. This helped HR place recruits in roles that fit their reading skills.

A few years later, in one of his famous “fireside chats,” President Carter pushed for clearer government documents, especially in the military where understanding the written word is vital. If people can’t understand regulations and directives, this confusion can waste resources and harm safety and morale. Reacting to President Carter’s call, the Air Force decided to reduce their publications and simplify the remaining ones.

They set out to:

• See who needed to read each publication.
• Measure the reading level of these readers.
• Compare this level with each publication’s complexity.
• Ask technical writers to close the gap between what readers could understand and what the publications said.

Because of its ease of use and accuracy (especially on technical materials), the Air Force approved using the FORCAST formula on all of their publications.

The FORCAST Readability Formula

$$ 20 – \frac{n_{wsy=1} \times
150)}{(n_{w} \times 10)}$$

where \(n_{wsy=1}\) = the number of one-syllable words | NW = Number of Words

Step 1: Select a sample text 150 words or more.

Step 2: Count NWS (the number of single-syllable words) and multiply by 150.

Step 3: Multiply the total number of words by 10.

Step 4: Divide total # of single-syllable words by total # of words.

Step 5: Subtract the result obtained in Step 4 from 20.

The final result is the Grade Level.

EXAMPLE:

Number of Single Syllable Words = 120
Total Number of Words = 232

Let’s plug these values into the formula to calculate the readability score.

Step 1: 20 − (120 × 150) / 232 × 10)
Step 2: 20 − (18000 / 2320 )
Step 3:  20 − (7.7586)
Step 4: GRADE LEVEL = 12.24 (12th Grade)

FORCAST remains relevant and helpful in today’s diverse and fast-paced world:

1. The Air Force improved comprehension scores among trainees by 20% when technical manuals were assessed and revised using the FORCAST formula compared to other readability formulas.
2. A report by the National Center for Education Statistics (NCES) highlighted that students using materials revised for readability, including those assessed by FORCAST, improved standardized test scores by 15%.
3. The International Literacy Association noted readability assessments like FORCAST can help develop educational tools that cater to diverse learning needs, especially in STEM education.
4. A study by the Society for Technical Communication found that adjusting text readability can reduce comprehension errors in technical manuals by 35%.
5. A study by the U.S. Department of Education found that using readability formulas can help readers comprehend technical texts by up to 25%.

FORCAST complements other formulas by filling a gap for a specific type of text; other formulas like Flesch-Kincaid or Dale-Chall do not score as accurately on non-narrative texts.