Diagnostic daytime multiple sleep latency test (MSLT) is used to diagnose narcolepsy and to measure the degree of daytime sleepiness. It measures how quickly you fall asleep in quiet situations during the day. It also monitors how quickly and how often you enter REM sleep.
Array formulas provide a way by which Excel users can discover such useful information. To explain the power of array formulas I'll use this database. It shows sales by Seller, Product, Region, and Customer, with Quantity and Total Sales, in dollars. I named each column of data with the label shown in row 1.
The Excel INDEX function returns the value at a given position in a range or array. You can use index to retrieve individual values or entire rows and columns. INDEX is often used with the MATCH function, where MATCH locates and feeds a position to INDEX. The value at a given location.