Monitoring supplie expense

Bill,
Not sure if this is what your talking about, but one thing we did with supplies was to determine the correct on-hand qty. We collected the data on daily, weekly & monthly use of each item and calculated what we wanted our on-hand qty to be taking into account the lead times on each item. Our analysis results showed we had six months of inventory on items that had two day lead times (however we were ordering replacement supplies each week) further analysis revealed that we had a vendor change and our lead time went from three months to two days, but nothing was put into place to align our re-order points.
Now for the overall budget monitoring process, we have a +/- 3% of total budget spend each month, we allow for some variance due to billing delays (budgeted for this month, paid next month). Any line item outside of the set range (+/- 3%) requires a detailed comment. (Natural gas prices went up, electricty rates, volume increase etc…)
Hope this helps.
GDS

We took historical usage data, number of items used per day, per week, per month, calculated the basic stats (mean, stdev). Mean + 3 stdev = our 95% CI stock level. Item by item we analyzed what we wanted our safety stock level to be based on how critical the item is and the lead time.  
So item “A” calculated to be 250 units per week, we are 95% confident that if we start out Monday with 250 units we will have enough supplies to last all week.(Item “A” has a two day lead time) Also you have to consider lead time and minimum order qty of the supplier, Our items safety stock levels range from 3 days to 3 weeks.

hi
try fish bone, it is old but still do it best
yours
DaveAllah