The Automated Readability Index - ARI - is useful for technical writing. Find out how you can use it. 

What is the Automated Readability Index?

The ARI assesses the U.S. grade level required to read a piece of text. 

In some ways, it is similar to other formulas. Its difference is rather than counting syllables, it counts characters. The more characters, the harder the word. It also counts sentences. This sets it apart from some other formulas.

Where did the test come from?

ARI was designed for military use in 1967. It was for real-time monitoring of readability on typewriters. It offered an automated counting method. It has similar results to other frameworks. This validates its accuracy.

How does the test work?

The ARI formula is as follows:

The Automated Readability Index (ARI) | Readable, free readability test

The initial calculation used an external piece of equipment. This was an Index Tabulator, attached to a typewriter. It counted the number of keystrokes, words and sentences in any passage. This allowed for real-time tabulation.

When is the Automated Readability Index most useful?

The ARI is suited to technical writing.

A comprehension study was carried out on Navy personnel.

The formulas they selected all had a sentence variable. These are more accurate for technical material. They argued that full comprehension was essential.

Manuals were far above the reading level of staff. The Chief of Naval Technical Training said this was a long-standing problem. The study also showed the differences between formulas. ARI was more reliable for their use case than Flesch.

This is because automation improved accuracy. It offered a simplified solution at the time.

Another study researched its usefulness to the U.S. Air Force. This was amid financial concerns about lapses in communication. They argued that sentences must count for adult reading material. They  also raised other factors. A general interest reader might like a simplified document. Someone reading with purpose may be able to handle a difficult text.

Automated Readability Test (ARI) table conversion | Readable, free readability test

ARI was useful to them for its speed. For technical texts, speed and efficiency are key.

These studies highlight the importance of clarity. It means reaching a wider audience. In this case, readability is fiscally vital. ARI helped pinpoint where to improve trainee resources.

Laura Kelly

Laura is a Marketing Executive at Readable. She loves coffee, literature, weightlifting and film photography.