The direction of a correlation is either positive or negative. In a negative correlation, the variables move in inverse, or opposite, directions. In other words, as one variable increases, the other variable decreases. For example, there is a negative correlation between self-esteem and depression. In other words, the higher your self-esteem, the lower your feelings of depression.
Excel Communications was founded in 1988 by Dallas entrepreneur Kenny Troutt as a long distance reseller in the US telecom sector at the birth of telecom deregulation.
Before Microsoft's Excel came about, a Harvard MBA student and his former MIT classmate built the first spreadsheet software for the Apple II. It was 1979 and Dan Bricklin and Bob Frankston wanted to see their calculators come to life. They wanted to be able to change numbers in their calculations and update their final answers. By creating VisiCalc, the first electronic spreadsheet, that's exactly what they did. Bricklin and Frankston would work at night because computer time was cheaper at night.