In a previous post, I laid out some of my rules for implementing a RAG status, which when used with discipline, can greatly help in project communications especially with demystifying areas or workstreams for your project team. I would still recommend any aspiring project manager to learn about the RAG status, it has become part of project management lore, and tradition in some organisations, where people expect to see some kind of RAG. Familiarity is good, but don't be too pedantic about it!
I am not so sure about RAG any more...I've come to love-and-hate the RAG...It's a tool that I impress on my project managers to use, but I feel less inclined to use the RAG in upwards-communications. Of course, it depends...
I've been running projects for close to ten years now, starting with the usual small pieces of work, 3-6 month projects, 2-4 teams, one customer; then moving on to large teams (20+) scattered around the world, multiple projects with multiple teams, 12-24 months projects. So I've come to appreciate the softer side of management, to the extent that, RAG status is almost meaningless to people not responsible for managing projects or workstreams. You can waste a lot of time justifying why you as a project manager (PM), have settled to communicate the status using the said-colour (say Red), and that it is entirely within your right as PM to use your judgement, after-all, it is something that you gotta deliver!
Managing stakeholder expectations is key to the success of any project, ultimately the stakeholder is happy that his/her expectation has been met. This is a little challenging especially when there's multiple stakeholders who hold the same pecking order in the org structure, and are contributing teams to a unified project, multiple departments coming together to deliver a huge feature, end-to-end. Getting consensus at this level is always troublesome, do you really want everyone to buy-in to the why you communicate a project's status?? You can of course try, get them together, talk them through your flow-charts and state models, explaining what "On Target - Risk" means and why it's Amber, or what does "Slipping - Not Yet Mitigated" Red means, or "Slip but expect to Complete" Amber means.
You can even explain how your Excel / MS Project Gantt includes the twenty odd sub projects tracking every single detail, bubbling up to each milestone, and how you run macros to determine if dates are being met, exceeded, and the algorithm you use to group individual task-level RAG items up to represent the group status of a parent milestone (and explain why you might have some Red tasks, but overall the milestone is still Amber or even Green). You could even explain your Critical Path items, PM 101 discussions, explaining why "Red - Slipping not yet mitigated" is a call to action for the stakeholders to actually do something, to help you recover things that is potentially beyond your control...