The factors that can contribute to employee turnover

Examine the factors that can contribute to employee turnover and identify strategies for retaining and engaging employees.
Case background
Several talented employees have recently left Sambian Partners and and it's not clear whether it's a sign or a coincidence. The architecture and engineering firm's latest defector refuses to tell the head of human resources, Mary Donillo, why he was unhappy. And the self-administered employee surveys don't reveal much.
Before posting in the discussion boards, read the case “Why Are We Losing All Our Good People?” https://hbr.org/2008/06/why-are-we-losing-all-our-good-people
• Who’s responsible for retaining and engaging employees? What’s leadership’s role? HR’s role? The manager’s role?
• What changes would you recommend Sambian make to its current practices for monitoring dissatisfaction?
• What recommendations would you make to Sambian to help them retain and engage their employees?