In our last lesson, we looked at the continuous measurement system known as frequency. Frequency is a very good method for collecting data on discrete behaviours ? things like the number of correct answers a student makes, the number of items packaged per hour or the number of times somebody hits themselves across a day.
However, it is not always a useful metric. For example:
Eileen is a mother of a toddler. She is concerned about her child?s crying. She decides to measure it and uses frequency recording.
At the end of the week, she notes that her child cried twice on Monday, once on Tuesday, did not cry on Wednesday, cried four times on Thursday and cried once on Friday.
Using frequency, we would conclude that crying was similar on Tuesday and Friday, and was much worse on Thursday. However, in reality, the episode of crying on Tuesday lasted for one hour, while the episode on Friday lasted for three minutes. Also, on Thursday, each episode lasted for less than ten seconds.
In this scenario, frequency would not be reliable metric. A better metric would be duration.
Duration is the length of time a single instance of a target behaviour occurs for.
It is appropriate for behaviors that have a distinct onset and ending, or for those that occur at very high rates. For examples, tantrums, crying or running.
Duration recording might involve, starting a stopwatch when a behaviour begins, then stopping the stopwatch when the behaviour ends. The behavioural definition should make the onset, and offset, clear to the observer. After stopping the stopwatch, you would record the length of time the behaviour occurred. You would repeat these steps every time a behaviour occurred during the observation period. At the end of the observation period, you would calculate the total duration of the behaviour, for that day, by adding the duration of each episode.
Examples Lorraine is currently learning how to ride a bike. Her carer records that she is able to successfully ride her bike for 10 minutes before needing to take a break. The duration of successfully riding the bike is 10 minutes.?????????????
Another example, When assessing Luigi’s readiness for school, an educational psychologist noted that he would sit in an instructional context for 4 minutes. In this scenario, duration recording is more useful than frequency recording because how long Luigi will sit in an instructional context is more important than how often he sits with regard to assessing somebody for school readiness.
In general, duration recording is useful when there is a clear beginning and end to the behaviour and when the length of time the behavior occurs (its temporal extent) is the primary concern.
It might not be useful for behaviors that start and stop quickly or occur at a very high frequency or in circumstances where an observer?s attention is shared between multiple people.