Briefly define the ethnocentric, polycentric, regiocentric, and global staffing approaches

What will be an ideal response?

Ethnocentric staffing approach is used to fill key managerial positions with people from the headquarters—that is, parent-country nationals (PCNs).
With a polycentric staffing approach, local managers—host-country nationals (HCNs)—are hired to fill key positions in their own country. This approach is more likely to be effective when implementing a multinational strategy.
In a regiocentric staffing approach, recruiting is done on a regional basis—say, within Latin America for a position in Chile. This staffing approach can produce a specific mix of PCNs, HCNs, and TCNs, according to the needs of the company or the product strategy.
In the global staffing approach, the best managers are recruited from within or outside of the company, regardless of nationality. This practice—recruiting third country nationals (TCNs)—has been used for some time by many European multinationals.