A stock variance does not identify its cause. First compare product movements over the same period and in the same unit.
Review four sources separately
Compare received quantity with the invoice; subtract sales and inter-store transfers, then add recorded disposal and damage. This gives expected closing stock. Compare it with a shelf and backroom count.
Code the gap as receiving-count error, system-entry or transfer error, documented waste, or unexplained inventory variance. For each event, record SKU, lot, quantity, time and supporting document or photo.
If waste rises, review it by product group, expiry date, shift and temperature record. A repeated pattern can point to an ordering or handling process to inspect; do not assign a cause without evidence.
Repeat the reconciliation weekly using the same method. State any change in count timing, units or movement records in the comparison.