Greetings from one of the newest members to the Cove! Here's my 2 cents worth (that's 0.02 CDN, though)....
My organization has four possible reactions to a situation. The "index" for these four options is detailed in our Nonconformance and OFI Guidelines Matrix, which details the parameters for each of the options. When a situation occurs, we refer to the Matrix which will provide guidance on how much action is required. If there is more than one possible option to take (things aren't always black and white in the land of ISO, are they?), we take the "higher" route.
1) A "Nonconformance" is a simple discrepancy with the system, requires some form of corrective action, and life goes on. A quick-and-dirty fix to an issue easily addressed.
EXAMPLE: A small windstorm blows through your trailer park and results in a few garbage cans impaling themselves upon your mobile abode. Action? Tape some Spam Cans on your home - scientific studies have shown this to be an effective deterent against strong winds.
2) "Corrective Action" is required when there is a break down within the system or when the item is rather extensive and will require the use of various problem-solving techniques. We document the Root Cause, Action Plan (and Results), and the Verification Plan (and Results) to demonstrate that the discrepancy has been addressed appropriately.
EXAMPLE: A tornado rips through your trailer park and, for reasons unknown to us, Mother Nature decides that your palatial residence should be a riverboat instead, and places you in the middle of the nearby lake. You buy a new and improved trailer (this one already has the pink flamingos on the front "lawn"), and tape Spam Cans all over it, and even duct tape the perimeter of your "property". As we all know, nothing beats duct tape. Your verification plan is that no tornado will touch your home for a period of three months.
3) "Preventive Action" is implemented when there is an adverse trend. Our Key (Performance) Indicators are monitored on the stop-light system (red, yellow, green). Two consecutive yellows, followed by a red means that a PAR is required. This system was implemented before I arrived, and while I don't find it's the greatest, it's not an item I'm will to change at the moment. (bigger fish to fry within our QMS
) Root Cause and Action Plan is usually easy in this area. For the Verification Plan, as this based upon an adverse trend, we designate x-number of months as the time to monitor the issue and verify that our actions have reversed the negative trend.
EXAMPLE: The number of tornados that have ripped the walls off of your home and resulted in your fellow trailer park residents seeing you decked out in a mud mask and pink curlers has increased over the past several years. You decide to tape Spam Cans to your trailer, and will monitor if this adverse trend reverses.
4) And finally, we come to an "Opportunity for Improvement." This is for items where the system is working beautifully, but there may be another way to make it more effective and/or efficient. Root Cause is not possible here, neither is a Verification Plan. Action Plan and Results, though, are possible. The recipient of an OFI is to analyze it and determine if it is feasible/practical/appropriate and has some form of ROI. Depending upon the analysis, the OFI is either accepted or rejected. If accepted, an Action Plan is developed and the results documented. This is how we're addressing the Continual Improvement aspect of ISO 9001:2000.
EXAMPLE: You've survived countless tornados and ridicule from your neighbours (they just can't forget the sight of you in pink curlers)..but, hey, you're still alive. OFI here...move. And the local real estate agent has heard about some lovely condominium buildings being built in the Everglades.
Rather simplistic examples, I realize, but it's Sunday, the sun is shining, and there's plenty of snow to play in. Life doesn't get much better than this!