When reality and the data in your system do not agree, you have contaminated data. The system says you have 10,000 cases but you actually have 9,850. A customer’s ship-to address is out of date. You have the same piece of information in two places in two applications or even two systems, but they do not agree. That means one or both are contaminated. Contamination can be caused by many things. Transactions causing a change in the data may have been inaccurately recorded. In the inventory example above, one of the many transactions that change the on-hand quantity could have been inaccurate. Maybe the physical act was flawed. A batch sheet calls for 1,000 pounds, the transaction is recorded as 1,000 but the picking resulted in more or less than 1,000 pounds. When material is placed in a location, the location is incorrectly reported, resulting in two pieces of contaminated data.

Time delays can cause temporary contamination. The recording of the transaction is delayed so that for a period of time, the data does not reflect reality. No harm, unless a decision will be based on the contaminated data. Contaminated data can have a negative impact on business. Catastrophic problems include a recall, losing a customer or a major financial write-off. Less of an impact is carrying too much or too little inventory or shorting a customer unnecessarily.