Final answer:
The correct answer is that external customers should not be invited to help design a firm's appraisal system since they do not have an in-depth understanding of the company's internal performance metrics and procedures.
Step-by-step explanation:
The question regarding who should not be invited to help design your firm's appraisal system encompasses understanding the roles and relevance of various stakeholders in the performance appraisal process of a business. When designing an appraisal system, it is vital to involve parties that have a direct stake in the performance outcomes of the company's employees.
Among the options provided:
- Purchasing leadership and buyers are closely involved in the company's internal operations and procurement processes, therefore they typically provide valuable insights on performance metrics related to purchasing and supply management.
- Internal customers are those within the firm who depend on the performance of the firm's employees, so their feedback can help align the appraisal system with internal expectations and standards.
- However, external customers, while they are the recipients of the final goods or services, usually do not have the detailed insight into the company's internal performance metrics and employee roles. Thus, they are not typically involved in the design of the company's internal appraisal systems.
Therefore, the correct answer is c. External customers.