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.
In earlier versions of Excel, many people created slow-calculating worksheets, and larger worksheets usually calculate more slowly than smaller ones. With the Excel 2007 Big Grid, performance really matters: Slow calculation makes it more difficult for users to concentrate, and it increases errors.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.