This the information I provided for prospective participants while I was collecting data:

"I'm interested in finding out how the CEFR descriptors work when you use them to assess learners. I ask you to do this in two ways: first to assess two learners whom you know well, so you are able to judge several aspects of their competence; then to assess some samples of writing by learners whom you've never met, so you can only judge some aspects of their writing (but you have an actual example of this in front of you)."

In practice,  this is what I asked participants to do:

1. Complete an initial online survey. This will ask some basic information about you, your teaching experience and your kind of teaching you are currently engaged in (secondary school, private language school, university...). It will also ask what levels you are currently teaching.
2. Choose two students, at two different levels. I will tell you which levels to choose from using information you have given me in step 1 above. 
3. For each of these two students, complete an online survey consisting of 40 "can do" statements. I will send you two emails, each with a link to a survey for one of your two chosen students student.
4. Complete another (final!) survey, containing  some samples of students' writing contributed by other participants during an earlier phase of the study. You are asked to assess these using a short list of "can do" statements

All of the information that you sent was  treated as confidential. I will not reveal your name, or any information which might enable other s to identify you, in any publication. Similarly, I will not reveal the identities of any of your students. The samples of students' written work that sent and/or assessed are anonymous: all personal and place names have been removed.