Baseline Cognitive Testing

This document set describes the baseline phase of the cognitive testing, conducted during the recruitment phase of the cohort from 2008 until the completion of the baseline in March 2015.

It provides an overview of the time frames, testing structure and participation details.

Note that, in a small number of cases the timestamps in the dataset refer to dates in 2005. This was an error resulting from the the failure of the CMOS battery in the laptop used for the cognitive test. When this happened, the laptop's internal clock was set to its arbitrary start-of-life date (January 2005) when it powered-up. There was no Internet-based time correction available in those days.