A review of the literature reveals both random and systematic errors ("bias") in the use of self-reported measures, but there remains some controversy over the magnitude of such errors. In particular, researchers have shown that over-reporting of height is more common among older survey respondents [3,4]. In addition, it has often been reported that men are more likely than women to overestimate their height, while women, particularly young women, are more likely to underestimate their weight [3,5]. Some researchers have also found systematic variations in the BMI based on the racial or ethnic background of interview respondents. For instance, Mexican Americans and, in particular, Mexican American women tend to underestimate their weight, resulting in underestimates of the prevalence of obesity in this group [6]. In a study of Mexican citizens, others also found that BMI values calculated from self-reported height and weight underestimated BMI values based on measured height and weight --- a tendency that increased with age [7]. However in one study [8], it was reported that Mexican American adults tend to underestimate their weight less than non-Hispanic white
