Implementation of a sample design for a survey of program participants using time-location sampling

Area of Science:

• Nutrition Science
• Public Health Research
• Longitudinal Cohort Studies

Background:

• The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) aims to improve nutrition for vulnerable populations.
• Understanding feeding practices is crucial for WIC's effectiveness.
• Previous studies highlighted the need for longitudinal data on WIC participant feeding behaviors.

Purpose of the Study:

• To assess feeding practices and behaviors of WIC-participating women and children.
• To evaluate the impact of WIC prenatal support and education on feeding.
• To describe the sampling methodology for the WIC Infant and Toddler Feeding Practices Study-2 (WIC ITFPS-2).

Main Methods:

• Employed time-location sampling (TLS) to recruit a cohort of infants around birth.
• Utilized a stratified, multistage probability sampling design.
• Conducted interviews with mothers, including prenatal interviews for early enrollees.

Main Results:

• Successfully generated a probability sample, albeit with geographic and size exclusions.
• Encountered challenges in WIC site identification and accurate enrollment flow prediction.
• Addressed issues with incomplete WIC site lists and enrollment count discrepancies.

Conclusions:

• Time-location sampling is a viable, though challenging, method for recruiting WIC participants.
• The study design allows for tracking feeding practices from infancy through childhood.
• Addressing sampling challenges is critical for ensuring the representativeness of WIC research cohorts.