In a typical spare parts inventory network to be supported there will always be part numbers for which operational reliability parameter values turn out to be significantly different (and in particular worse) compared to prevailing data. To manage this, the D-SIMSPAIR Field Parameter Adjustment function can be run on a regular basis with the latest part request, repair or re-order event data that can be uploaded from the Master Data Module at any time. A specific purpose is to identify troublemakers, i.e. part numbers for which the performance in terms of reliability, repair or re-order is not meeting expected performance and may have an impact on the overall Service Level performance. The User can prioritise corrective actions accordingly and decide whether and to what extent planning parameters such as MTBUR or Repair Turnaround Time should be adjusted, also taking into account trends and seasonality effects.