Discuss the difference between reliability and validity and how each are ensured when implementing
assessments for students with moderate to severe disabilities. In addition, looking at the
"Professional Development Presentation: Descriptive Statistics," how comfortable are you working
with statistics? Why is it important to be familiar with statistics when looking at assessment data?
Reliability - is the degree to which the result of a measurement, calculation, or specification can be
depended on to be accurate.
Validity - is the quality of being logically or factually sound; soundness or cogency.
Reliability has to do with consistency of an accurate result. Validity has to do with how well the
measurements, calculations or specifications, measure what it is meant to measure. For an
assessment to be reliable it also needs to be valid. For example, when working on a students goals
and collecting data - Sherry will write her first and last name correctly, improving her writing and
spelling skills from 20% accuracy in 4 consecutive trials to 100% accuracy in 4 consecutive trials as
measured by student work. What we are looking for is Sherry to write her first and last name
correctly each time she is given same opportunity with 4 trial.
A few years ago, I was working towards my BA in psychology and had to take a statistics class. I
really struggled in the class and had to take it three times before passing with a C. I understand the
basic concept of collecting data to show the progress our students are making as well as assessing
where student present levels are. I get confused as to defining and describing how statistics work.
Being familiar with statistics allows a teacher to properly collect, analyze, interpret, explain and
present collected data on students to show present levels and student growth.
