Why Readability Matters for SLP Reports
Speech-language pathologists write for parents, not for other clinicians. A parent handout, an IEP summary, a diagnostic report, a discharge plan, and an informed-consent form all need to land at a reading level that the parent can actually understand. The National Assessment of Adult Literacy (2003) found that roughly 36 million U.S. adults have limited health literacy and that the median reading level among adults with limited health literacy is 5th to 6th grade. The American Medical Association, the National Institutes of Health, and the Centers for Disease Control and Prevention all recommend that patient-facing materials be written at or below a 6th-grade level.
The gap between clinician writing and the target is large. Studies of discharge instructions, informed-consent forms, and patient handouts in speech-language pathology, pediatrics, and rehabilitation routinely find average reading levels in the 9th to 12th grade range even when the authors are specifically asked to "write simply." Jargon, nominalisations, and long compound sentences push the grade level up three to five grades per pass without the author noticing. Running the text through a readability formula before sending it to the parent is the single most reliable way to catch this gap.
Multiple formulae, one decision. No single readability formula is definitive. Flesch-Kincaid captures sentence length and syllable density. SMOG is tuned for health materials and for 100 % comprehension. Gunning Fog is the classic medical-writing measure. Reading Ease is a 0 - 100 "ease" score (higher = easier). The consensus grade (the mean of Flesch-Kincaid, SMOG, and Gunning Fog) is a robust one-number summary and is what the analyzer classifies against the AMA / NIH / CDC parent-readability target of grade 6 or below.
What Each Formula Measures
Flesch Reading Ease (Flesch 1948). A 0 - 100 "ease" score where higher is easier. The formula weights words per sentence and syllables per word: FRE = 206.835 - 1.015 * (words / sentences) - 84.6 * (syllables / words). A Reading Ease of 90 - 100 is "very easy" (5th grade); 80 - 90 is "easy" (6th grade); 70 - 80 is "fairly easy" (7th grade); 60 - 70 is "plain English" (8th - 9th grade); 50 - 60 is "fairly difficult" (10th - 12th grade); 30 - 50 is "difficult" (college); and 0 - 30 is "very difficult" (college graduate). Microsoft Word reports this score natively.
Flesch-Kincaid Grade Level (Kincaid et al. 1975). The U.S. school grade level required to understand the text, derived from the same two inputs as Reading Ease: FKGL = 0.39 * (words / sentences) + 11.8 * (syllables / words) - 15.59. The U.S. Department of Defense adopted Flesch-Kincaid as the standard readability formula for technical manuals in 1978, and it is now the most widely reported grade-level formula in medical writing, education, and EHRs.
SMOG Grade (McLaughlin 1969). SMOG = 1.0430 * sqrt(polysyllables * (30 / sentences)) + 3.1291. SMOG counts the polysyllables (3 + syllable words) in a 30-sentence sample and converts that count into a grade level. The McLaughlin (1969) validation targeted 100 % comprehension — the grade level at which 100 % of readers at that grade will understand the text — versus the 50 - 75 % target of most other formulae, which is why SMOG is preferred for health materials where the cost of misunderstanding is high (informed consent, medication instructions, discharge plans).
Gunning Fog Index (Gunning 1952). Fog = 0.4 * ((words / sentences) + 100 * (complex / words)). "Complex" is classically defined as a polysyllable after excluding proper nouns, -es / -ed / -ing inflections, and compound words. This implementation uses the Kincaid-style 3 + syllable definition for parity with SMOG and to keep the calculator deterministic. The Gunning Fog score will therefore run slightly higher than a hand-calculated Gunning Fog score on passages with many proper nouns or inflected polysyllables.
How to Lower the Grade Level
If the consensus grade is above 6, the two biggest levers are sentence length and syllable density. Every readability formula depends almost entirely on those two inputs.
Shorten sentences. The average sentence length in a parent handout should land around 12 - 15 words. Long compound sentences ("The evaluation, which was conducted over two sessions and included both formal and informal measures, indicated moderate delays in both receptive and expressive language domains.") routinely add 2 - 3 grades on their own. Break every sentence longer than 20 words into two.
Replace multisyllabic jargon with plain-language equivalents. "Receptive language" becomes "how well your child understands what people say." "Expressive language" becomes "how well your child talks." "Articulation" becomes "clear speech." "Phonological processes" becomes "sound patterns." "Narrative discourse" becomes "telling stories." Every swap of a polysyllable for a 1 - 2 syllable equivalent drops the grade level. A single pass of jargon replacement can drop the consensus grade by 2 - 4 grades.
Cut filler and nominalisations. "Your child is demonstrating a pattern of difficulty with production of the /s/ sound" becomes "Your child has trouble saying /s/." Nominalisations ("demonstrating", "production", "utilisation") push up both sentence length and syllable density at once.
Separate the clinician body from the parent summary. The full clinical report will often stay at a high-school or college reading level because of unavoidable professional terminology (CELF-5, MLU, phonological processes, SALT, VFSS). That is fine. Write a one- or two-paragraph parent-summary section at the top or bottom of the report and paste that paragraph alone into the analyzer — the parent section should land at or below grade 6 even when the body does not.
Verify with a re-run. After every revision pass, re-paste the text into the analyzer. The consensus grade should drop monotonically; if it does not, check for a new long sentence or a new multisyllabic word that was added in the revision.
Using the Analyzer in Practice
Parent handouts and IEP summaries. Paste the full handout or summary. The consensus grade should land at or below 6. If it lands above, run a jargon-replacement + sentence-splitting pass and re-check.
Clinical report parent-summary paragraph. Most SLP clinical reports are 4 - 10 pages long and cannot reasonably be kept below grade 6 across the entire report. The solution is a separate parent-summary paragraph (typically 3 - 6 sentences at the top or bottom of the report) written in plain language. Paste that paragraph alone into the analyzer.
Informed-consent forms. The entire form should land at or below grade 6. The AMA and the NIH explicitly cite informed consent as the highest-stakes readability target because a form the parent cannot understand cannot legally count as informed consent.
Discharge instructions. Pair the analyzer with a teach-back review at the discharge visit. Aim for grade 6 or below and confirm with a verbal recap from the parent.
Medication and therapy home programs. Home programs are only effective if the parent can read and execute them. Paste the full home program into the analyzer and keep every instruction paragraph at grade 6 or below.
Research consent and study materials. IRBs increasingly require Flesch-Kincaid grade 6 or below for consent forms and participant-facing materials. Run the analyzer before IRB submission to catch the grade-level violation in advance.
Spanish and other non-English. This analyzer implements English formulae only. For Spanish, use the Fernandez-Huerta or Szigriszt-Pazos formula; for French, the Kandel-Moles formula; for German, the Wiener Sachtextformel. Consensus grades across languages are not directly comparable.
