Associations between obesity and cognition in the pre-school years.

Objective: To test the hypothesis that obesity is associated with impaired cognitive outcomes in the pre-school years.

Methods: Associations were examined between weight status at age 3-5 years and cognitive performance at age 5 years. Cognitive outcome measures were tests of pattern construction (visuospatial skills), naming vocabulary (expressive language skills), and picture similarity (reasoning skills).

Estimating the probability of rare events: addressing zero failure data.

Traditional statistical procedures for estimating the probability of an event result in an estimate of zero when no events are realized. Alternative inferential procedures have been proposed for the situation where zero events have been realized but often these are ad hoc, relying on selecting methods dependent on the data that have been realized. Such data-dependent inference decisions violate fundamental statistical principles, resulting in estimation procedures whose benefits are difficult to assess.