Assessing the Performance of a Nutrition Knowledge Questionnaire With a Low Socioeconomic Status Population Using Rasch Analysis.

Parents and preschool teachers play a key role in shaping children's dietary behaviors. Knowledge of nutrition and healthy dietary choices is a key component to improve dietary habits and reduce the prevalence of obesity and associated co-morbidities. Using valid and reliable instruments is necessary for accurate assessment of knowledge to tailor interventions and measure effectiveness specific to the population of interest. The objectives of this paper are to (1) identify potential gaps in the baseline nutrition knowledge among parents and teachers using a previously validated questionnaire prior to a preschool obesity prevention intervention; and (2) assess the instrument's reliability and construct validity for a low socioeconomic status population using a post hoc Rasch analysis. Participants included 177 parents and 75 teachers who participated in a Head Start intervention study. Knowledge scores, instrument reliability, and item fit and difficulty were assessed using a Rasch analysis; t-tests were used to determine differences in scores between parents and teachers. Parents answered 38% of questions correctly while teachers correctly answered 46% of the questions. Adequate item fit and reliability were indicated for Sections 1 and 2 of the Nutrition Knowledge Questionnaire (NKQ). Section 3 demonstrated less adequate reliability. The items were found to adequately and reliably define the unidimensional measures of the three components of knowledge represented in this instrument, providing evidence of construct validity. However, Rasch measures indicated the NKQ overall was difficult for participants. Recommendations for improving the instrument for nutrition education/intervention and research practice areas related to obesity and obesity-related conditions are addressed.