3. Research methodology
3.1 Data
To analyse inventory performance over time, the study could be executed either at the firm level using disaggregated
data or at the industry level using aggregated data. This study is based on disaggregated data at the firm level,
mainly in order to guard against an aggregation bias, i.e. firms performing differently cancelling each other out in
each sector. In the majority of cases, firm-level data are only publicly available for stock-listed corporations, which,
of course, represent just a fractional amount of the total number of German companies. All data used were taken
from Thomson Financial’s Worldscope Global Database.