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.
Excel 2007 has three new functions that you can use to SUM, COUNT, or AVERAGE using multiple criteria. In earlier versions of Excel, you had to use slow-calculating, hard-to-understand array formulas or SUMPRODUCT to use multiple criteria. The new functions are easy to use and fast to calculate.n Excel 2007, you should always use the SUMIFS, COUNTIFS, and AVERAGEIFS functions instead of array formulas wherever you can because they are much faster to calculate. In versions before Excel 2007, array formulas are often used to calculate a sum with multiple conditions.