Executive compensation, especially long-term incentive compensation, is complicated. First, the strategic decisions made by top-level managers are typically complex and nonroutine; as such, direct supervision of executives is inappropriate for judging the quality of their decisions. Because of this, there is a tendency to link the compensation of top-level managers to measurable outcomes such as financial performance. Second, an executive's decision often affects a firm's financial outcomes over an extended period of time, making it difficult to assess the effect of current decisions on the corporation's performance. In fact, strategic decisions are more likely to have long-term, rather than short-term, effects on a company's strategic outcomes. Third, a number of other factors affect firm performance. Unpredictable economic, social, or legal changes make it difficult to discern the effects of strategic decisions. Thus, although performance-based compensation may provide incentives to managers to make decisions that best serve shareholders' interests, such compensation plans alone are imperfect in their ability to monitor and control managers. Although incentive compensation plans may increase firm value in line with shareholder expectations, they are subject to managerial manipulation. For instance, annual bonuses may provide incentives to pursue short-run objectives at the expense of the firm's long-term interests. Supporting this conclusion, some research has found that bonuses based on annual performance were negatively related to investments in R&D, which may affect the firm's long-term strategic competitiveness. Although long-term performance-based incentives may reduce the temptation to under invest in the short run, they increase executive exposure to risks associated with uncontrollable events, such as market fluctuations and industry decline. Long-term incentives may not be highly-valued by a manager, thus, firms may have to overcompensate managers when they use long-term incentives.