If you are an expert and you know, you know. But on a lot of our project activities or work packages, we don’t “know” the cost, effort or duration so we estimate. If we estimate based on our experience and or memory, regardless of how expert we might actually be, it typically is nothing more than WAG – a Wild-Ass Guess.
And as a side note, there is nothing wrong with saying ass in a blog, even in the Old Testament, “Judah got on is ass and rode away.”
Most people put a S in front of WAG to form SWAG. The S can refer to what ever makes sense in your situation, it could be Scientific, Statistical, Stupid, Simple, Silly, Sophisticated, etc.
Wikipedia says this about the use of SWAG:
SWAG is used to describe an estimate derived from a combination of factors including past experience, general impressions, and heuristic or approximate calculations rather than an exhaustive search, proof, or rigorous calculation. The SWAG is an educated guess but is not regarded as the best or most accurate estimate. The SWAG is not computed or proven rigorously, but the proponent asserts his or her own judgement suffices to rationalize the estimate; and it may, in time, be viable to produce a rigorous forecast of increased precision.
Years ago the Army web site told the history of popular military acronyms. WAG is an old military term, the website claimed, and it goes all the way back to when two armies would face off against each other on the battlefield. The evening before the big battle, the story goes, the general of the army is walking among the troops and comes across a private preparing himself for what he thinks he needs to do before battle and the general, almost absently asks the private, “Son, how strong is the enemy going to be tomorrow?” The private thinks to himself, “How the hell would I know, they have been keeping that a secret.” But he is under a lot of pressure to respond because he is being asked to provide an estimate by a very powerful person. The Army website then stated, “It is not recommended to use WAG with senior officers.” The why was not provided because it is obvious that WAG can lead to disastrous consequences.
WAG doesn’t work in the military and it doesn’t work in project management. See blog post on: Estimating is what you do when you don’t know. ~ Sherman Kent
What was the rationale for the Iraq War? Some experts claim the Bush administration fabricated reasons for a war it wanted, this may or may not be true, but at the very least, the invasion was based on WAG. Even Colin Powell, long after his presentation to the United Nations Security Counsel, stated that he was at the Pentagon every day and no one told him the information he was presented with wasn’t factual. Frontline states in an article called, “Colin Powell: U.N. Speech ‘Was a Great Intelligence Failure'” that Powells’s speech…
…to the United Nations, laying out the Bush administration’s rationale for war in Iraq, is a “blot” on his record. The speech set out to detail Iraq’s weapons program, but as the intelligence would later confirm, that program was nonexistent.
“Blot on his record.” What an understatement. Thousand of US personnel killed, and an estimate by university researchers in the United States, Canada and Baghdad in cooperation with the Iraqi Ministry of Health suggests the Iraqi death toll is as high as 500,000. Not including all of the lives ruined, the injured and all of the suffering.
In addition, the financial cost of the Iraq War is 1.7 trillion with an additional $490 billion in war veteran benefits that could grow to $6, trillion in the next 40 years.
WAG – simply avoid it, it doesn’t provide value and it can lead to serious consequences in any context.