Working on ideas for an organisational design research project I was taken aback by the realisation that the old directories in my organisation were a treasure trove of information on what the organisation was, and how peoples careers evolved in the past. Very upsettingly this treasure trail stopped in 1999 when the intranet took it all online and the data vanished. Does training a cohort have any impact on attrition and career development - we shall never know, short of running a 20 year project. The observational data is gone.