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.
Managers typically use gross profit to compute gross profit margin, also known as gross margin. This is a ratio showing the efficiency in which the business turns revenue into gross profit. The formula is gross profit divided by revenue for the period. Using the same numbers, you divide $210,000 by $420,000 and get .50. You multiply this by 100 to convert it to a percentage of 50. This is seemingly a strong gross margin, though you have to compare it to industry norms and prior periods to know for sure.