Assessment, Diagnosis, and Clinical Reasoning in Speech Therapy
The assessment process
Know the sequence: screening, referral, case history, standardized and nonstandardized testing, observation, and diagnosis. Understand validity, reliability, sensitivity, and specificity. Standardized tests yield standard scores and percentiles; criterion-referenced measures describe functional performance. Dynamic assessment (test–teach–retest) helps distinguish language difference from disorder. For aphasia, use measures like the Western Aphasia Battery conceptually; for speech, use single-word and connected-speech sampling.
Clinical reasoning
Understand hypothesis-driven assessment: form a hypothesis, gather data, revise. Integrate findings from multiple sources (client, family, teachers, medical records). Distinguish diagnosis (what is the disorder) from prognosis (expected outcome) and from treatment planning (what to do next).
Traps in questions
A common trap is relying on a single test score-always triangulate. Another is confusing a language difference (dialect, bilingualism) with a disorder. Do not equate a low score with a diagnosis without considering the test's norming sample and the child's background. Also avoid treating a screening result as a diagnosis.
Rule of thumb
No single measure is diagnostic. Combine standardized data, observation, and functional impact before concluding.
Worked example: A bilingual child scores low on an English-only vocabulary test. Before diagnosing a disorder, assess in the home language and use dynamic assessment; the low score may reflect language exposure, not impairment.