- Sampling WIC participants within a sampled recruiting window. The WIC participant sample will be designed such that the total target number of sampled WIC enrollee is spread uniformly across the 80 sampled sites; that is, the recruitment of study participants will be designed so that each site will be expected to yield 98 sampled WIC enrollees. An important part of our sampling plan is the concept of recruiting "windows." A recruiting window will be a string of consecutive workdays during which we will be recruiting new WIC enrollees at each sampled service site. These windows will vary in length from 7 to 66 workdays. The length of the window will be pre-determined, based on typical daily enrollment volumes (obtained from the State following selection of the phase 1 sample of first-stage sampling units) and will be calculated in such a way as to yield an average of 98 sampled WIC enrollees per site. The 80 windows will be randomly assigned to a spread of starting dates across the 20-week field period for recruiting, with the pool of possible starting dates for a given site determined based on its average daily enrollments and enrollment schedule. Due to the variations in actual WIC enrollments over time, the actual number of sampled enrollees who enroll in WIC during the specified recruiting window will vary from site to site.