A: The collaboration for successful studies starts even before the moment you contact them: how you plan, how you train your staff, what kind of letters you send out, how the person who schedules meetings talks to these people. Also important is the ease of participation. You may want to plan home visits because it makes a huge difference for participants whether they have to make the effort or whether the researcher is making the effort. I know that is a kind of a switch of how things are generally done, but it is very important, and it also tells the participant that they are really important. You have to give the participants the feeling that they are colleagues in this endeavor to find out more information, to learn more about a particular condition, so they aren't just people that you ask a few questions and then you push them out the door. They are the most important because without them, you can't do it, and that message has to come across. You should not underestimate what it takes for someone to participate in your study. Do they need childcare? Do they need transportation? All these things are important.

A: What we have found very important is if you ask for family or friends who might always know where they are, find people who don't happen to live in the same house. Nowadays, you can easily use email addresses, social security numbers, and maiden names to track participants. Our rule is to collect this information as often and as extensively as we can because of course friends who know where they are may also change every year, or the family member who knows them best may have moved. Also, you can ask in the consent form whether you can contact a child's school to find out where they may have moved to because officially school records ought to move from school to school. Work addresses can be useful as well, and if people don't want to be contacted at work, just knowing the type of work they do can be helpful. I once had an interviewer who knew a participant had worked in a laundromat, and that interviewer visited about 30 laundromats and eventually found the participant. Anything that helps to direct your search is good.

A: We don't use those services as a first step to locate someone, but we have used them occasionally. Those services search by social security numbers usually, and they don't give financial information. Because the services use public records, we have not asked our participants for permission to use them.