Four basic types of IOA as described by Johnston and Pennypacker (2009): Total agreement - Smaller total ÷ Larger total X 100 = % Agreement Exact agreement - Total agreements ÷ Total number of intervals X 100 = % Agreement Interval agreement - Total agreements ÷ Total number of intervals X 100 = % Agreement Occurrence/nonoccurrence agreement - Total agreements ÷ Total number of intervals X 100 = % Agreement

"The extent to which the independent variable is applied exactly as planned and described and no other unplanned variables are administered inadvertently along with the planned treatment" (Cooper Heron, & Heward, 2007, pp. 706-707).

Interobserver agreement (IOA) "...refers to the degree to which two or more independent observers report the same observed values after measuring the same event" (Cooper, Heron, & Heward, 2007, p. 111).