There are a myriad of studies that have been completed on retaining research participants (Robinson et al., 2007 for a systematic review of retaining research participants [mostly in health care]). Their basic overall finding is that those studies who use a number of different ways (aka are more dynamic) of retaining participants will retain more than those who don’t ‘go the extra mile’. And those studies who help ease burdens on participants retain more participants.
Although I am not studying this topic, I feel like I have a good indication why Head Start and Early Head Start preschool teachers are staying involved in the study. Of course I agree with Robinson, in that, some of my teachers may not have continued participating if I didn’t go into their classrooms, allowing them to leave their classrooms to complete the questionnaire (easing their ‘lack of time’ burden). Additionally, when creating the questionnaire, it was designed so that people could complete the form in 10 minutes (if they filled it out completely) or in two minutes (if they simply circled a number on the likert scale, and didn’t write comments explaining themselves); after all, one of the largest complaints I hear from Head Start and Early Head Start teachers is the amount of paper work that is required of them compared to other preschool programs.
So trying to design a study that can meet the needs of the researcher, while meeting the needs of its participants is definitely important in retaining participants.