Such an initial assessment, based on the information available at the time, is the prior probability of success.
Not taking prior probability into account partially or completely is called base rate neglect.
That suggests a prior probability of guilt of 1 in 150,000.
Generally the prior probability is estimated using the prevalence of a disease within a population or at a given testing location.
Before the first inference step, is a set of initial prior probabilities.
For example, if 1,000 people could have committed the crime, the prior probability of guilt would be 1/1000.
The term is used to contrast the case of a weak or uniformative prior probability.
The approach is subjective, and this requires the assessment of prior probabilities, making it also very complex.
In other words, for large n, the effect of the prior probability on the posterior is negligible.
What is important is the relationship between the loss function and the prior probability.