ADDIE is a systematic model for instructional design and human performance improvement. It is a recursive model composed of five phases: Analysis, Design, Development, Implementation and Evaluation. The evaluation phase of the process is intended to measure the effectiveness and efficacy of a course, training, project or any other performance improvement intervention. Although evaluation occurs at the end of the process, it is important to note the recursive nature of the process--it is not really the end.
The 6 Rs of Evaluation model, developed by Charla Johnson, aims to further specify the steps of an effective evaluation process that circles back to any of the previous ADDIE phases as needed based on the outcomes of the evaluation.