>> A scrum master is not a manager. He's only mean to organise a handful of meetings and deal with impediments. These should not take any significant time.
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The Scrum Master does indeed manage impediments to the projects. They act as a "shit umbrella" - protecting the team from all external influences that are deemed detrimental to actually doing the job. They "keep a finger on the pulse" of the team - identifying problems (sometimes between individuals, sometimes with individuals, sometimes with external 3rd parties interfering). They are there to allow the team to develop the software they are employed to do... in a pleasant environment (that doesn't include phones ringing all the time, doesn't include constant multi-tasking, and doesn't include managers walking up and asking dumb questions every 2 minutes).
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I disagree with a previous poster that the "top people" should be Scrum Masters. Whilst the role must have someone with a strong personality and understanding of the business relationships between the project and the rest of the organisation (in a large corporate at least), they do not need to have any "hands-on" technical ability (or involvement). For similar reasons, an intern is probably not a good solution as Scrum Master either. So-called "soft" skills are more important here.
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The Scrum Master role is as facilitator - and to help "keep the team honest" with respect to Agile principles and process (regardless of what flavour your organisation has chosen to attempt).
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I've been working in Agile teams now for 4+ years - seen good and bad implementation... had lots of success - and some failures (don't we all). Agile tends to work with enthusiastic, smart, intelligent and "bright" people. It doesn't do so well if the people are dumb, unfocussed or demotivated. The Scrum Master role includes identifying these people and either working with them to "lift their game" - or works with HR to get them out of the team.
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I would object strongly if the Scrum Master role was not a full time position, and if they were wanting to act as some kind of technical team lead. Let developers do the development... let people who understand the technology stack make those recommendations... but don't confuse the roles
Life would be so much easier if we could just look at the source code. -- Dave Olson