Which measure provides the most useful data when conducting nutrition screening on preschool children at a health fair?

The measure that provides the most useful data when conducting nutrition screening on preschool children at a health fair is weight for stature. This measurement is particularly valuable in assessing the nutritional status of young children because it allows for the evaluation of weight in relation to height, which is critical for estimating body composition and identifying potential growth issues.

In preschool children, understanding weight relative to stature can help identify those who are underweight, overweight, or at risk for obesity. Given the rapid growth and development that characterize this stage of life, assessing weight for stature offers immediate insight into whether a child's weight is appropriate for their height, which is more relevant than absolute weight or height alone.

While body mass index (BMI) is useful, it may not be as effective in this age group due to the quick changes in body composition that can occur. Comparatively, height for age primarily indicates linear growth but does not provide a comprehensive picture of nutritional status. Skinfold thickness is often used in body composition assessments but may not be practical in a health fair setting where quick screening is necessary. Thus, weight for stature stands out as the most useful measure in this context.