Identifying Credit Risk Measurement Techniques

Michael is a credit analyst evaluating a corporate bond issued by XYZ Corporation. He is particularly concerned about the company's creditworthiness and wants to employ a credit risk measurement technique to assess the likelihood of default. He considers several methodologies, including distance to default and credit ratings. While evaluating these methodologies, Michael needs to identify which measurement explicitly quantifies the likelihood of default based on the volatility of the firm's asset value relative to its liabilities.

Which credit risk measurement technique should Michael prioritize to best suit his needs?