The reason for not relying solely on firm’s available data is that
they could suffer from underreporting (think about missed accidents) and limited exposure (so that real hazards may not have materialized yet and hence not being represented in the statistics,
but may still pose a significant risk). The use aggregated data, specific of an industrial sector, rather than data for individual firms,
can possibly give a better, or at least a wider, picture of the risk
than company-specific data. Still, the use of company-specific data
helps in analysing and underlining special features which might be
present within particular firms.