S. I. Newhouse School of Public Communications, Syracuse University, Syracuse, NY 13244-2100, USA.
J Nutr Educ Behav. 2011 Sep-Oct;43(5):331-8. doi: 10.1016/j.jneb.2010.09.016. Epub 2011 Jul 8.
To examine the influence of body mass index (BMI), sex, and race on college students' optimistic bias (OB) concerning the healthiness of their own lifestyles relative to the "average college student" and best friends.
Cross-sectional survey.
Large university campus.
College students recruited from first-year classes (1,398 female, 985 male).
Student height, weight, sex, race, and assessments of lifestyle healthfulness for self, best friends, and the "average college student."
Paired 2-way t tests compared lifestyle ratings for self and others. One-way analyses of variance compared differences between BMI categories. Tukey Honestly Significant Difference tests tested all pairwise comparisons. Analyses of covariance controlling for BMI scores tested sex and race differences (P < .05).
College students in all BMI categories were optimistically biased in comparisons to the average college student. Optimistic bias differences were significantly smaller, however, for self and close friends. Sex and race also influenced the extent and nature of OB judgments.
Optimistic bias may limit students' willingness to adopt and maintain more healthful behaviors. Optimistic bias can be reduced or even eliminated if close friends are specified as comparative targets. Health education campaigns, particularly those using socially normative approaches, should consider the impact of comparative target, sex, and race on OB.
考察体重指数（BMI）、性别和种族对大学生相对于“普通大学生”和最好的朋友对自己生活方式健康程度的乐观偏差（OB）的影响。
横断面调查。
大学校园。
从一年级班级招募的大学生（女性 1398 名，男性 985 名）。
学生身高、体重、性别、种族以及对自我、最好朋友和“普通大学生”生活方式健康状况的评估。
配对 2 样本 t 检验比较自我和他人的生活方式评分。单因素方差分析比较 BMI 类别之间的差异。Tukey Honestly Significant Difference 检验测试所有两两比较。控制 BMI 评分的协方差分析测试性别和种族差异（P<.05）。
所有 BMI 类别的大学生在与普通大学生的比较中都存在乐观偏差。然而，与自己和亲密朋友的比较，乐观偏差的差异明显较小。性别和种族也影响 OB 判断的程度和性质。
乐观偏差可能会限制学生采取和维持更健康行为的意愿。如果将亲密朋友指定为比较对象，乐观偏差可以减少甚至消除。健康教育活动，特别是那些使用社会规范方法的活动，应考虑比较对象、性别和种族对 OB 的影响。
