According to ZDNet's IT Facts blog (by the way, a great place to get your daily dose of data): "71% of top performers listed pay among the top three reasons they would consider leaving their employer. Only 45% of employers cited pay as a top-three reason workers leave. Instead, employers thought promotion and career-development opportunities were more important. Another oft-blamed culprit, relationship with a supervisor, was cited by 31% of employers but 8% of top performers."
The post pulls from an article on The WSJ Career Journal covering the survey results of multiple studies. The article states, "The results suggest employers don't fully understand the needs of their top employees, frustrating companies' efforts to battle turnover as the labor market improves." So while many employers think workers are leaving because of greener pastures or interpersonal conflict, the real reason is money, particularly as employers make cutbacks to health-care and pension plans. Cash is king once again.
The only way for employers to deal with turnover and retention is head on. They should reevaluate compensation policies and offer bigger raises to top performer before they are poached by competitors!