Checklists provide a list of thoughts, emotions and behaviors that may be demonstrated by the individual, and may be filled in by either an evaluator or may be reported by the person themselves. Most checklists provide the symptoms associated with some kind of challenge (Gregory, 2004). Each symptom that is demonstrated is marked and once the entire list is completed, the total number of symptoms is totaled. Checklists are thus called additive methods of evaluation (Merrell & Harlacher, 2008). These are objective and easy to understand, and do not require as much time or expertise as interviews. They are also comprehensive, and allow the evaluator to identity less visible symptoms that could be missed during observation (Merrell & Harlacher, 2008).
The main issue with a checklist is that they do not allow one to estimate the magnitude of the symptom. While one person may exhibit the symptom rarely, another may exhibit it almost every day. At such times rating scales provide an advantage over checklists in that each selected item is also rated on a 3 point or 5 point scale ranging from never/rarely to always/frequently (Gregory, 2004). Thus, each symptom is provided with a weighted score all of which may be added to get a composite score. Rating scales are algebraic in nature, and the value assigned to each item provides a detailed understanding of the experience of the person (Merrell & Harlacher, 2008).
Checklists are valuable screening instruments that help in identifying person’s who need help; while rating scales are useful when trying to understand which symptoms are more dominant for a particular person (Gregory, 2004). Both these instruments are objective and easy to use, but are unable to provide the meaning associated with the symptoms by the individual. The validity of the responses depends on the honesty of the responses and it may become