Range Estimating was made popular by AACE Recommended Practice  41R-08, originally issued in 2008, and then in 2022 the RP was revised to provide the basis for the “AACE decision to change this RP’s scope and no longer recommend “range estimating” as covered in the original (2008) as a specific estimate ranging practice in support of risk analysis and contingency determination.”  This presentation will discuss what went wrong, what was wrong, how it has impacted the practice, especially as regards MC modeling, And let’s add to that: how the 2008 range estimating RP influenced thinking, which, without self-examination, may persist.  This presentation will highlight the differences between risk, contingency, causes & effects, and accuracy.  The idea of correlation and “orthogonality,” (a term that caught my eye from your April presentation) will be touched on, and there will be a demonstration of differences between modeling methods: those that are aligned with range estimating, and those that are more aligned with orthogonality.