Do these two columns move together?
CORREL measures how closely two columns move together, on a scale from -1 to 1. Near 1 they rise together, near -1 one rises as the other falls, and near 0 there is no straight-line relationship at all.
Two warnings come with it. A correlation near zero only rules out a *straight-line* relationship, a strong curved one can score zero. And a correlation near one says nothing whatever about cause: ice cream sales and drowning deaths correlate beautifully, because both follow the weather.
In E2, work out the correlation between B2:B9 and C2:C9. In E4, type Yes or No: does this prove advertising caused the sales?
The grid for this exercise is part of the paid half.
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