Consider a corporate bond with a credit rating of BB. The issuer operates in a cyclical industry and has experienced a decline in earnings due to recent economic downturns. As part of your credit analysis, you decide to measure the credit risk associated with this bond. One important measure you are considering is the probability of default (PD) over the next year, which is influenced by both the issuer's financial condition and market conditions.
Which of the following options provides the most appropriate method to estimate the one-year probability of default for the issuer of this bond?