The nature of a decision aid is to provide assistance to the users. The assistance should be evaluated from two different perspectives, as human decision making models are mostly based on two approaches: process oriented and outcome oriented. Hence, the property of providing useful assistance (i.e., helpfulness) through a decision aid needs to consider both process and outcome factors. This study explores the constructs of measuring helpfulness through a systematic process which result in four dimensions being identified: reliability, decision making effort, decision process awareness, and confidence. A quantitative validation was also reported on measuring perceived helpfulness of a computerized decision aid for youth, known as YouthPDA.