1 Onset of sleep from time the lights were turned off; this is called  sleep onset latency  and normally is less than 20 minutes. ( 2 Note that determining sleep and awake is based solely on the EEG. Patients sometimes feel they were awake when the EEG shows they were sleeping.
The direct cost margin is calculated by taking the difference between the revenue generated by the sale of goods or services and the sum of all direct costs associated with the production of those goods, divided by the total revenue.
Expressed as a percentage, the direct cost margin indicates what portion of each revenue dollar is retained as profit after accounting for only those expenses incurred for the production of goods and services. The direct cost margin is often referred to as the gross margin, and is an important metric in corporate finance. Depending on how revenue and expense data are labeled on company financial documents, this margin can be expressed two ways: Direct Cost Margin = (Revenue - Direct Costs) / Revenue. or. Gross Margin = (Revenue - Cost of goods sold) / Revenue