According to this scale, your document scores <%= case analysis.flesch_kincaid_reading_ease.try(:round) when 90..500 'Very easy to read. Easily understood by an average 11-year-old student.' when 80..90 'Easy to read. Conversational English for consumers.' when 70..80 'Fairly easy to read.' when 60..70 'Plain English. Easily understood by 13- to 15-year-old students.' when 50..60 'Fairly difficult to read.' when 30..50 'Difficult to read.' when 10..30 'Very difficult to read. Best understood by university graduates.' when -500..10 'Extremely difficult to read. Best understood by university graduates.' else analysis.flesch_kincaid_reading_ease.try(:round) end %>

The Flesch–Kincaid scale is a readability test designed to indicate how difficult a passage in English is to understand. It was originally designed by Rudolf Flesch and J. Peter Kincaid for the U.S. Navy, but is commonly used to this day to measure and ensure some legal documents are written at no higher than a ninth-grade reading level.

The readability test is backed up by a separate test called the Flesch–Kincaid Grade Level which measures readability in the same way, but weights those measurements in a slightly different way. This is the scale used by Microsoft Word and Grammarly to calculate the reading level of a document.

A higher score on this scale indicates a document is easier to understand.