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.
Again, gross margin is just the direct percentage of profit in the sale price. In accounting, the gross margin refers to sales minus cost of goods sold. It is not necessarily profit as other expenses such as sales, administrative, and financial must be deducted.ross Margin (%) = (Revenue â Cost of goods sold) / Revenue. It can be expressed in absolute terms: Gross margin = net sales â cost of goods sold + annual sales return. or as the ratio of gross profit to revenue, usually in the form of a percentage: