Shortages and surpluses: where they come from
When a count shows less stock than the records, people usually think of theft. When it shows more, they are puzzled and often ignore it. In reality, both shortages and surpluses come from the same set of causes, and most of them are about information, not crime.
Receiving errors
Goods are received in a different quantity than the delivery note says, or the wrong item is booked. A box is opened and the contents are counted as one unit. These errors create a gap on day one.
Wrong substitutions
Two similar products are mixed up when picking or booking. One shows a shortage, the other a surplus, and the total value may be almost unchanged. These are some of the most common surprises in a count.
Unrecorded returns and write-offs
Goods are returned by a customer and put back on the shelf without a document, or damaged goods are thrown away without being written off. The system never learns about it.
Timing differences
A shipment is booked before it leaves, or a receipt after it arrives. If the count falls in between, the numbers differ even though nothing is lost.
Damage, expiry and natural loss
Some goods lose weight, leak, break or expire. If these losses are not recorded when they happen, they appear later as an unexplained shortage.
Theft and misuse
Real theft exists, but it is rarely the biggest cause. It becomes more likely where access is uncontrolled and nobody is clearly responsible for each area.
What to do
- Recount every significant difference before drawing conclusions.
- Group the differences by cause: data, process, damage, loss.
- Fix the process behind the most common cause first.
- Record decisions and follow up in the next count.
Surpluses deserve attention too
A surplus is not good news. It means that goods are in the warehouse that the records do not know about, or that the same goods were booked twice somewhere else. Surpluses often show up as shortages in another item or another warehouse, so investigate them with the same care.
Keep a simple cause log
For each difference, record the item, the quantity, the likely cause and what was done. After a quarter you will see that three or four causes explain most of the problem, and you can fix those first.
Look for patterns. A single difference is an incident. The same item or location appearing again and again is a process problem, and that is where the real savings are.