Certain Utility Analysis reports allow the user to specify prorated values. This feature allows data to be smoothed, to remove variations caused by the varying length of billing periods. For example, it is quite realistic that a meter reader could take a reading after 24 days, and then another 37 days later. A month-to-month energy use comparison based on the raw data would be difficult. If the user were to specify prorated data, mec would calculate daily values for both billing periods, and then establish "virtual" billed values based on the length of each calendar month. The reported values would be differ from the billed amounts, but would be suitable for comparison.