13. List and briefly explain the four basic sources of variation, and explain why it is important for managers to be able to effectively deal with variation. Explain the four basic sources of variation1. The variety of goods or services being offeredThe greater the variety of goods and services, the greater the variation in production or service required. 2. Structural variation in demandThese variations, which include trends and seasonal variations, are generally predictable. They are particularly important for capacity planning. 3. Random variationThis natural variability is persent to some extent in all processes, as well as in demand for services and products, and it cannot generally be influenced by managers. 4. Assignable variation These variations are caused by defective inputs, incorrect work methods, out-of-adjustment equipment, and so on. This type of variation can be reduced or eliminated by analysis and corrective action.Why it is important for managers to be able to effectively deal with variation? Variations can be disruptive to operations and supply chain processes, interfering with optimal functioning. Variations result in additional cost, delays and shortages, poor quality, and inefficient work systems. Poor quality and product shortages or service delays can lead to dissatisfied customers and can damage an organization's reputation and image, that the ability to deal with variability is absolutely necessary for managers.