log-odds
If the event is a binary probability, then odds refers to the ratio of the probability of success (p) to the probability of failure (1-p).
Plain English Explanation
If the event is a binary probability, then odds refers to the ratio of the probability of success (p) to the probability of failure (1-p). For example, suppose that a given event has a 90% probability of success and a 10% probability of failure. In this case, odds is calculated as follows:
The log-odds is simply the logarithm of the odds. By convention, "logarithm" refers to natural logarithm, but logarithm could actually be any base greater than 1. Sticking to convention, the log-odds of our example is therefore:
The log-odds function is the inverse of the sigmoid function. ---
How is it used?
Practitioners refer to log-odds when building, training, or evaluating machine learning systems. It appears in research papers, product documentation, and technical discussions about AI capabilities and limitations.