In the world of project management and the process improvement efforts needed to increase the Probability of Project Success anecdotes appear to prevail when it comes to suggesting alternatives to observed dysfunction.
If we were to pile all the statistics for all the data for the effectiveness or not effectiveness of all the process improvement methods on top of each other they would lack the persuasive power of a single anecdote in most software development domains outside of Software Intensive Systems.
Why? because most people working in small groups, agile, development projects, compared to Enterprise, Mission Critical can't fail, that must show up on time, on budget, with not just the minimum viable products, the the mandatorily needed viable capability - rely on anecdotes to communicate their messages.
I say this not from just personal experience, but from research for government agencies and commercial enterprise firms tasked with Root Cause Analysis, conference proceedings, refereed journal papers, and guidance from those tasked with the corrective actions of major program failures.
Anecdotes appeal to emotion. Statistics, numbers, verifiable facts appeal to reason. It's not a fair fight. Emotiona always wins without acknowledging that emotion is seriously flawed when making decisions.
Anecdotal evidence is evidence where small numbers of anecdotes are presented. There is a large chance - statistically - this evidence is unreliable due to cherry picking or self selection (this is the core issue with the Standish Reports or anyone claiming anything without proper statistical sampling processes).
Anecdotal evidence is considered dubious support of any generalized claim. Anecdotal evidence is no more than a type description (i.e., short narrative), and is often confused in discussions with its weight, or other considerations, as to the purpose(s) for which it is used.
We've all heard stories, ½ of all IT projects fail. Waterfall is evil, hell even estimates are evil stop doing them cold turkey. They prove the point the speaker is making right? Actually they don't. I just used an anecdote to prove a point.
If I said The Garfunkel Institute just released a study showing 68% of all software development projects did not succeed because of a requirements gathering process failed to define what capabilities were needed when done, I've have made a fact base point. And you'd become bored reading the 86 pages of statistical analysis and correlation charts between all the causal factors contributing to the success or failure of the sample space of projects. See you are bored.
Instead if I said every project I've worked on went over budget and was behind schedule because we were very poor at making estimates. That'd be more appealing to your emotions, since it is a message you can relate to personally - having likely experienced many of the same failures.
The purveyors of anecdotal evidence to support a position make use of a common approach. Willfully ignoring a fact based methodology through a simple tactic...
We all know what Mark Twain said about lies, dammed lies, and statistics
People can certainly lie with statistics, done all the time. Start with How to Lie With Statistics But those types of Lies are nothing compared to the able to script personal anecdotes to support a message. From I never seen that work, to what now you're telling me - the person that actually invented this earth shattering way of writing software - that it doesn't work outside my personal sphere of experience?
An anecdote is a statistic with a sample size of one. OK, maybe a sample size of a small group of your closest friends and fellow travelers.
We fall for this all the time. It's easier to accept an anecdote describing a problem and possible solution from someone we have shared experiences with, than to investigate the literature, do the math, even do the homework needed to determine the principles, practices, and processes needed for corrective action.
Don’t fall for manipulative opinion-shapers who use story-telling as a substitute for facts. When we're trying to persuade, use facts, use actual example based on those facts. Use data that can be tested outside personal anecdotes used to support an unsubstantiated claim without suggesting both the rot cause and the testable corrective actions.
