In my interviews, you’ll hear us talk about a scale that each interviewee completes for me. I’m a psychologist, I had to! This scale is free and available for all noncommercial use.
Lyubomirsky, S., & Lepper, H. (1999). A measure of subjective happiness: Preliminary reliability and construct validation. Social Indicators Research, 46, 137-155. The original publication is available at http://www.springerlink.com.