Data Collection (Continued)

Lecture Notes for September 1SPEC 3020

Fall 2009

http://coefaculty.valdosta.edu/pgunter/SPEC3020/index.htm

Accuracy of Recording Systems

• Frequency is most Accurate

• Interval recording is next most accurate

• Time sampling is the least exact

Interval Recording

• Partial Interval Recording – the behavior does not consume the entire interval

• Whole Interval Recording – the behavior consumes the entire interval

• Continuous vs. Non-continuous intervals

• Recording several behaviors

• Recording behaviors of several students

Time Sample

• The student is observed only at the end of the interval

• As the interval gets longer, the similarity between the data recorded and the actual occurrence of the behavior probably decreases.

Important Points and Differences Concerning Interval Recording and

Time Sampling • Both provide an approximation. Neither is as accurate as

event recording.• Interval recording provides a closer approximation to

actual occurrence• Interval recording is usually used for a short observation

and time sampling for longer periods• Time sampling is easier to manage while teaching.• Occurrence is noted and recorded at any time during

interval recording and only at the end of the interval when using time sampling.

• Observers report the number of intervals, not the number of behaviors.

Reliability

• Gross 5/5 100%

• Occurrence only reliability 3/6 50%

(when target occurs in less than 75% of intervals)

• Non Occurrence reliability 4/7 57%

(when target behavior occurs in more than 75% of the intervals)

X X X X X

X X X X

Observer 1

Observer 2

Factors Affecting Data Collection and Reliability

• Reactivity – Something new has been introduced

• Observer drift –tendency to change stringency of operational definition

• Complexity – the more complex the system the more reliability is in jeopardy.

• Expectancy – Preconceived notions

Continuous recording systems

http://www.youtube.com/watch?v=bozysY7cG3M

• Write an operational definition for a behavior of your choice and describe the data collection system you will use to gather data related to the behavior.