Improve Diagnostic Accuracy by Understanding the Numbers Behind Our Tests

Test developers create tools to help us measure receptive language skills, expressive language skills, speech skills, pragmatic skills, cognition, and so on. As evaluators, we use those tools to guide our diagnostic decisions which, in turn, lead to placement decisions for students. Will a child receive special education services or not? These are big decisions that ride, in part, on the standardized testing tools we choose. So, we owe it to our students to really understand the tools we use. We need to select tools that give us thorough information about the content area we are testing. We need to understand what the reliability and validity estimates of the test are. Most importantly, we need to use the information provided by the test developers about sensitivity and specificity to adjust our standard practice of using the same cut-point for every test. We’ll also consider cultural and linguistic diversity can impact test results, and steps we can take to avoid misdiagnosis.