How Probability of Default Is Actually Calculated in the Real World (And why it’s much simpler than you think)
If you have ever tried to understand Probability of Default (PD) , chances are you’ve been told things like: “PD comes from complex statistical models” “You need logistic regression” “You need advanced mathematics” “This is only for quants” That framing scares people away. The truth is simpler. In the real lending world, PD starts with a very basic question : Out of all loans that are performing today, how many of them will become 90+ days past due within the next 12 months? That’s it. Everything else comes later. Let’s walk through this step by step, using plain data and plain logic. First, let’s fix the definition in your head In most retail lending setups: Default = loan reaching 90+ DPD 12-month PD = probability that a loan which is currently below 90 DPD will migrate to 90+ DPD within the next 12 months PD is not : Recovery Loss Write-off Provision PD is only about migration to default status . Once this clicks, everything else becomes ...