Conversion factors can be categorized into different types. One type of conversion factor is used to convert raw agricultural commodities into consumer products, such as when converting beef from a carcass weight to a boneless weight, or when converting a dozen shell eggs to kilograms of dried egg. These factors may change over time with changes in agricultural production and marketing practices. In contrast, conversion factors for weights and measures for agricultural commodities and their products are constant over time. For example, two pints of liquid always equal one quart.