Final answer:
No, the sum of firms' marketing efforts does not equal industry marketing efforts. The impact of larger firms is relatively bigger.
Step-by-step explanation:
No, it is not true. The sum of firms' marketing efforts does not necessarily equal industry marketing efforts. While firms in the same industry may collectively contribute to the overall marketing efforts, the level of contribution may vary based on factors such as market share, size, and resources.
For example, larger firms with a higher market share and more resources may have a greater impact on industry marketing efforts compared to smaller firms. The Herfindahl-Hirschman Index (HHI) is a measure used to assess market concentration and competition within an industry. It includes the market shares of all firms in its calculation, but the squaring of the market shares makes the impact of the largest firms relatively bigger compared to the 4-firm or 8-firm ratio.
Therefore, it is important to consider the individual marketing efforts of each firm in addition to the collective industry marketing efforts.