TY - JOUR
T1 - Variability in portion sizes of commonly consumed foods among a population of women in the United States
AU - Hunter, David J.
AU - Sampson, Laura
AU - Stampfer, Meir J.
AU - Colditz, Graham A.
AU - Rosner, Bernard
AU - Willett, Walter C.
N1 - Funding Information:
Reprint requests to Dr. David J. Hunter, Charming Laboratory, 180 Longwood Avenue, Boston, MA 02115. This work was supported by Research Grant CA40356-03 from the National Institutes of Health. The authors thank the registered nurses who participated in the study, Charlotte Petro for computer programming, and Susan Newman for preparing the manuscript
PY - 1988/6
Y1 - 1988/6
N2 - The use of food frequency questionnaires for measuring dietary Intake has become widespread in epidemiologic. studies. It has been suggested that inquiring about a person's usual serving size of each food, in addition to the frequency of consumption, will improve the accuracy of this method. This approach Implies that individuals characteristically eat a specific amount of any particular food, and that this amount can be reported with reasonable accuracy. To investigate the variability of portion sizes, the authors analyzed data for 68 commonly consumed foods, based on four one-week weighed diet histories recorded by 194 Boston-area women aged 34-59 years during 1980 and 1981. For each food, total population variance In portion size was partitioned into withln-person (in-traindividual) and between-person (interindividual) components. For all but seven food items (yogurt, liver, mixed vegetables, watermelon, pancakes/waffles, cold cereal, and cooked cereal) the within-person variance in portion size exceeded the between-person variance. The mean of the withln-person to between-person variance ratios, after exclusion of two outlying foods, was 3.4 for untransformed portion sizes, and 3.2 after portion sizes were log.-transformed. Foods with a high withln-person variance also tended to have a high between-person variance. The dominance of within-person variance in portion sizes suggests that the concept of usual portion size Is complex, and that subjects may experience substantial difficulty In specifying their "usual" portion size. The smaller contribution of between-person variance to the total variance in portion size suggests that specification of a standard portion size by the investigator may not introduce a large error in the estimation of food and nutrient intake.
AB - The use of food frequency questionnaires for measuring dietary Intake has become widespread in epidemiologic. studies. It has been suggested that inquiring about a person's usual serving size of each food, in addition to the frequency of consumption, will improve the accuracy of this method. This approach Implies that individuals characteristically eat a specific amount of any particular food, and that this amount can be reported with reasonable accuracy. To investigate the variability of portion sizes, the authors analyzed data for 68 commonly consumed foods, based on four one-week weighed diet histories recorded by 194 Boston-area women aged 34-59 years during 1980 and 1981. For each food, total population variance In portion size was partitioned into withln-person (in-traindividual) and between-person (interindividual) components. For all but seven food items (yogurt, liver, mixed vegetables, watermelon, pancakes/waffles, cold cereal, and cooked cereal) the within-person variance in portion size exceeded the between-person variance. The mean of the withln-person to between-person variance ratios, after exclusion of two outlying foods, was 3.4 for untransformed portion sizes, and 3.2 after portion sizes were log.-transformed. Foods with a high withln-person variance also tended to have a high between-person variance. The dominance of within-person variance in portion sizes suggests that the concept of usual portion size Is complex, and that subjects may experience substantial difficulty In specifying their "usual" portion size. The smaller contribution of between-person variance to the total variance in portion size suggests that specification of a standard portion size by the investigator may not introduce a large error in the estimation of food and nutrient intake.
KW - Diet
KW - Epidemiologic methods
KW - Food
KW - Nutrition
KW - Nutrition surveys
KW - Questionnaires
UR - http://www.scopus.com/inward/record.url?scp=0023900594&partnerID=8YFLogxK
U2 - 10.1093/oxfordjournals.aje.a114916
DO - 10.1093/oxfordjournals.aje.a114916
M3 - Article
C2 - 3369422
AN - SCOPUS:0023900594
SN - 0002-9262
VL - 127
SP - 1240
EP - 1249
JO - American journal of epidemiology
JF - American journal of epidemiology
IS - 6
ER -