We all make wrong assumptions every day. Even when we have the evidence in front of us we easily come to a wrong conclusion - trusting our senses and our instincts.
In fact we draw on past experience of patterns, connections and associations and then make an analogy with the current situation, but that's not important here.
Mostly, our assumptions are near enough and we just get on with life with no great harm done.
But by being conscious of how easily we are fooled we can very often bring about massive improvements - in performance, results and even lifestyle and wealth. In business, trusting your instincts all the time will probably mean you perform no better than average.
If you want to do better you have to be better, starting with the assumptions you make and the testing you can and should be doing instead.
For example, you might assume you know who your average customer is and, because of that, you might not try to sell them anything that you think they wouldn't want to buy. But when did you become that omniscient?
There's a famous story of a door to door salesman being chased down the street by an irate householder because he'd assumed - from the state of the house and the old car in the drive - that they wouldn't be interested in what he was selling, and so hadn't knocked on their door, although he'd called at most of their neighbours:
"Who are you to assume I can't afford it?" was the perfectly reasonable question.
One of the best ways to give your business a boost is to study very carefully the assumptions you're making about your market, your customers and even your own products and services, then challenge them.
Roy
PS. Even the most mundane jobs can make us think again. Today, I was washing up (doing the dishes) when I was surprised to notice that the plastic mixing spoon I was washing sank to the bottom of the bowl, when I'd expected it to float, while an apparently heavier hard plastic chopping board did the opposite - floated when it 'should' have sunk. And I do know about the law of floatation, by the way!
Even with the evidence of seeing and holding both objects, my senses had deceived me. Only testing gave me the truth.