This is an excerpt from a message thread that Jeff Parker wrote. It contains some good thoughts on screening and how to (ideally) get people to self-screen off trips rather than rejecting them.
If you've ever been screened, you know what the person on the other end of the line is going through. They want to get on the trip, and they want to seem worthy of being on the trip to you. But in many cases the participant doesn't really know if (s)he is qualified. If you never stretch, you will never get better, but you don't want to be in over your head, and you don't want to be at the end of the pack.
So the art to screening is to find out if the person is qualified, and if they are not, to make sure they don't wind up on the trip. Telling them 'no' isn't the only way to do this. It is often enough to describe, in clinical terms, what you will be doing.
"Well, Jeff, I'm glad you are interested in improving your Snowboarding Skills. We will be spending three days doing black diamond trails and we will do avalanche rescue drills where we bury each participant in snow and practice with guide dogs who dig the participants up. On the last trip, only two people were bitten badly enough to need stitches. Does this sound like a trip you would enjoy?"
Note there are no judgmental terms like "Wicked fast runs" or "Scary drops" that might imply how you feel, or how you think they should feel. You can, of course, decide how to present something if you don't want them on the trip - talk about the pitch of ascent rather than the views from the top.
Give them a graceful way to exit, but don't leave it up to them. You may have decided they are not going to be on the trip: what is up for grabs is who voices this thought first.
This also works if you haven't been able to tell if they are qualified. You always give everyone the information: if they meet your requirements for the trip, you can use an open ended question like the above to let them decline.
The requirements may start to diverge from the printed requirements. If everyone already on the trip is on the weak side or on the strong side, the trip may not match what you planned to do 3 months ago. Many of the folks signing up for Level 1 trips now have taken the CRCK 3 night class, and will be coming with more skills than we required.
I try to explain this to everyone as they sign up. "This is an introductory class, but we have a bunch of folks with more experience than you have. Does this sound like fun?" The answer could be "yes, then I can ask my peers" or "no, I hate being the slow one."
It works the other way, of course. You don't want a serial peak-bagger on your beginner stoll around Walden Pond. If they aren't happy to do the trip you are planning, they can make others self conscious as well.
Screening is an art.
Gordon Haff adds.
Another example from a recent signup: Paddler was interested in an L2 trip but described himself as a "fair weather" paddler who wouldn't be interested if there was a lot of wind. I told him that we would run the trip rain or shine and that there was open water which could be quite breezy even if it was calm closer to the shore. He decided (on his own) to do an easier trip first.
I also find that when writing trip descriptions a couple of words can go a long way towards setting expectations. For harder trips, phrases like "long day", "fast-paced", "tricky landing", etc. should be included as appropriate in assist in upfront self-screening (as can "leisurely pace", etc. in assist of an easier trip).