Final answer:
Stock number changes are made normally as a result of changes in the number of producers, government policy, and producer price expectations.
Step-by-step explanation:
Stock number changes are typically made as a result of several conditions. These include a change in the number of producers, a change in government policy, and a change in producer price expectations. Additionally, irregularities in the object being measured and other factors that affect the outcome can also lead to stock number changes.