MUFON's mission statement is: "The scientific investigation of UFOs for the benefit of all humanity." Not the 'crystal ball' method. I hate to say it but I've seen cases where the witness as much as said that the object in question was probably something that they just couldn't identify, only to read the Field Investigator's report and find out that they "feel" there was more to it than there really was. I'm sorry but "feel" doesn't cut it. It isn't evidence, and it's not something that can be scientifically proven.
I think what some Field Investigators are thinking is that no one will question their conclusion, and it will be case closed. That just isn't true. The better the sighting, landing, abduction case, or whatever kind of case it may be, the more evidence is needed, and more in-depth investigation is definitely required. The evidence has to be able to stand up to scrutiny, and as much supporting testimony from witnesses as possible should be gathered. The more witnesses an investigator talks to, the better they will be able to put together a comprehensive picture of what happened. One witness, and little or no evidence does not make a very convincing case.
So evidence is gathered, witnesses have been interviewed, and photographs have been taken. Sounds like everything is done, right? Wrong. The Field Investigator also needs to know about the weather conditions that day, and any astronomical data that might have a bearing on the investigation. One would look pretty ridiculous if they ignored a meteor shower while investigating a sighting of a fireball.
Flight data needs to be considered too. Any air traffic in the area needs to be accounted for, and a check of any local missile tests, or live fire exercises at any military installations in the area should be done as well. One should also consider if there are any holidays, or publicized events going on at the time, where those attending might be inclined to light Chinese Lanterns, or some such celebratory device.
One should also know the terrain around the area. Fortunately we can use Google Earth now to see exactly where a sighting occurred, and we can even use it to measure the distances involved.
As you can see, there is a lot that must be considered when investigating a sighting. If one makes the mistake of relying on only the report, and their feelings, they can be assured of coming to the wrong conclusion. As a Field Investigator it is imperative that each case be approached with an open mind, and that the evidence is what the conclusion is based on...not your gut feeling.