Longitudinal and Cross-Sectional Weighting of the Survey of Labour and Income Dynamics - ARCHIVED

The Survey of Labour and Income Dynamics (SLID), introduced in the 1993 reference year, is a longitudinal panel survey of individuals. The purpose of the survey is to measure changes in the economic well-being of individuals and the factors that influence these changes. SLID's sample is divided into two overlapping panels, each six years in length. Longitudinal surveys like SLID are complex due to the dynamic nature of the sample, which in turn is due to the ever-changing composition of households and families over the years. For each reference year, SLID produces two sets of weights: one is representative of the initial population (the longitudinal weights), while the other is representative of the current population (the cross-sectional weights). Since 2002, SLID has been producing a third set of weights which combines two panels that overlap to form a new longitudinal sample. The new weights are referred to as combined longitudinal weights.

For the production of the cross-sectional weights, SLID combines two independent samples and assigns a probability of selection to individuals who joined the sample after the panel was selected. Like cross-sectional weights, longitudinal weights are adjusted for non-response and influential values. In addition, the sample is adjusted to make it representative of the target population. The purpose of this document is to describe SLID's methodology for the longitudinal and cross-sectional weights, as well as to present problems that have been encountered, and solutions that have been proposed. For the purpose of illustration, results for the 2003 reference year are used. The methodology used to produce the combined longitudinal weights will not be presented in this document as there is a complete description in Naud (2004).