Definition: Time is broken into intervals, such as 1-minute intervals for 50 minutes, and data is taken at the end of each interval. Data is recorded as percentage of intervals in which the behavior is occurring. It is assumed the behavior occurred for the entire interval. It is best for continuous activity. There are three types: fixed, variable, and planed activity check (PLACHECK). Fixed: observation period in equal intervals. Variable: intervals are of variable length. PLACHECK: is used for group behavior. At the end of the interval, the data collector records the number of participants engaging in the target behavior. Data is reported as percentage of group engaging in target behavior for each interval.
Why it matters: This method of data collection method does not require continuous observation, making it more practical for teachers or other practitioners.
Example of use: A teacher is measuring on-task behavior for a student. She sets her phone to buzz every 2 minutes. When her phone buzzes, she records whether the student is on-task or not. She assumes the behavior occurred throughout the interval when calculating the student’s time on-task.
Gast, D. L., Ledford, J., & ebrary, I. (2014). Single case research methodology [electronic resource]: Applications in special education and behavioral sciences. New York, NY: Routledge.