Try it out at https://zaceno.github.io/happy
This web based app is meant to be loaded on a phone, and passed around among members of a work-team, letting each one anonymously answer the question: "How happy are you about your job?" on a scale of 1 (very unhappy) to 5 (very happy). The average value, is then presented as the "happiness Index".
There are a number of reasons why a team might do this. Basically a happy team is an effective team. Tracking happiness over time will confirm the team's efforts to improve, and can give early warning when high pressure is about to take its toll. It is also a good way to start a team-retrospective. After having answered the question, it's easier to answer the follow-up: "What could be different, so I would have voted higher?"