=+3 Jayne thinks further about her analysis, and discovers a significant flaw in her approach. She realises that advertising done in a given month should be expected to influence the following month’s sales, not necessarily the current month’s. She modifies her analysis by comparing, for example, October advertising expense with November sales revenue. The modified regression yields the following:

Revenue = $23 538 + (5.92 × Advertising expense)

Variable Coefficient Standard error t-Value