

Oneday versus usual intake
Two food consumption concepts must be distinguished: oneday intake and usual intake. Oneday intake is total nutrient intake over a specific 24hour period. These data were collected by the 2004 Canadian Community Health Survey — Nutrition during an interview in which respondents were asked to describe everything they ate from midnight to midnight the previous day. Usual intake is an overview of food typically consumed in a day, and it cannot be directly estimated based on oneday intake. However, estimates of the proportion of the population below or above a given threshold require a usual intake distribution.
Usual intake varies from one individual to another. Oneday intake varies not only from one individual to another, but also from day to day for a given individual. To estimate usual intake, daytoday variation for individuals was removed using Software for Intake Distribution Estimation (SIDE).^{3} With a series of mathematical transformations, this software is able to estimate each component of the variance and to estimate the distribution of usual intake of a nutrient.^{4,13} For these calculations, day of the week was used to partially account for the effect of classification.
