Explain what is meant by the notion of "trimming" a multiple regression result. Use the following example to illustrate your understanding of this concept. A bicycle manufacturer maintains records over 20 years of the following data: retail price in dollars, cooperative advertising amount in dollars, competitors' average retail price in dollars, number of retail locations selling the bicycle manufacturer's brand, and an indication whether the winner of the Tour de France was riding the manufacturer's brand (coded as a dummy variable where 0 = no and 1 = yes). The initial multiple regression result determines the following:

Using the "enter" method in SPSS, what would be the trimming steps you would expect to undertake to identify the significant multiple regression result? Explain your reasoning.