≡ Menu
Pawel Brodzinski on Software Project Management

When Assumptions Fail


Yesterday I had a free day. Once I woke up I realized we’re out of bread so I drove a couple of kilometers to a grocery to buy some. I expected to be back in a few minutes which unfortunately didn’t happen. Why? Because a few of assumptions I made were wrong. What could go wrong with such a simple task? Seems like a hell lot of things.

Assumption 1: I can safely use verge when going by the bus heading the other direction.

We have pretty narrow road and buses out there are huge. You know as huge as these 24-wheel trucks. OK, maybe I am exaggerating a bit but still you need to use verge to pass the bus safely. And probably 99 out of 100 times nothing would happen. But this time I hit curb built by some property owner across the verge. Like a speed breaker or something. On the verge. Why anyone would do something like that? Anyway that isn’t something you would expect. Neither did I.

Assumption 2: The car should deal with curbs.

Well, if the wheel hit it in the middle there wouldn’t be a problem. But I hit exactly the edge of curb damaging tire and rim. Two tires and two rims to be precise, since both front and rear wheels had a pleasure of meeting Mr Curb. And it was a deadly meeting.

Assumption 3: One spare wheel is enough.

Well, this one is true. Most of the time. If you aren’t out of luck. Like me. Yesterday. So I was standing there looking at one flat tire and listening to the sound of air escaping from another one and thinking how nice it would be if there was some bread at home in the first place. Fortunately rear tire wasn’t damaged so badly and leak stopped when pressure went down a bit. I changed front tire and headed last few hundred meters home. And yes, that was so close. And yes, I was lucky since I wouldn’t be able to drive much further than that.

Assumption 4: I can live without a car.

Well, I didn’t really assume this one.

Assumption 5: Spare wheel works well.

I had two wheels destroyed but I also had a spare wheel, which meant I need only one additional rim and one tire. Or so I though back then. I went to the center of the city (public transport, I love you) to steal my wife’s car (well actually she just gave me the keys) and then bought rim and took another tire from home. In Poland we change tires from winter to summer back and forth so everyone has plenty of spare tires in stock. With the new wheel ready I mounted it instead of partly damaged rear wheel and took a short ride. Very short actually.

It appeared that the problem with steering the car I’d experienced after the hit had nothing to do with partly damaged rear tire. The tire was gone and problem was still there. After short investigation it appeared rim of my spare wheel was damaged too. I think the word “elliptic” would suit better than “round” if you ask me to describe the rim. As you may guess elliptic wheels don’t work very well. It looks like my spare wheel was damaged from the very first day I bought the car which is a huge load of bad luck. It looked like I had still one wheel down despite my efforts.

By the way: who has ever checked whether a spare wheel works well? And I don’t think about the situation when you’ve had to use it, but to check it just in case of emergency? If your answer is positive you can see how it feels to stand out of the crowd.

Assumption 6: Your spouse will be fine even if you don’t pick her from work after stealing her car.

And yes, I mean your spouse, not mine. Mine definitely won’t be fine.


I could continue with my story telling you how I assumed the local dealer would have more than one suitable rim in stock or local service would try to fix one of damaged rims at the same day (they did actually; I had been very persuasive), but this post wasn’t supposed to be about my adventure with Mr Curb – the evil character.

What I’m trying to tell you is how many unconscious assumptions we make even in very simple situations. If I asked you what could go wrong in my Infamous Trip in Search of Some Bread you’d probably vote for forgotten wallet or shop closed for some reason. You definitely wouldn’t think of damaging two wheels at once on stupid curb.

There is one interesting thing more. Once the unexpected happened I implemented backup plan with the goal to fix the car to be able to get to work today. This plan incorporated other assumptions and one of the most important ones (good spare wheel) appeared to be wrong again. At that point of the story I had to implement a backup plan for a backup plan with even less time than before. I had new commitments too as I had to drive back to pick my wife up from work.

When I think about the story few things comes to my mind. Each is pretty sensible and yet we tend to forget about them when dealing with software projects.

  • We make tons of assumptions. Most of them unconsciously. And unconscious assumptions are far more painful to deal with (when they appear to be misassumptions) than conscious ones.
  • When we launch rescue plan we base on assumptions even more. We also tend to ignore all negative options and assume the most optimistic plan would work.
  • Clear goal helps very much in achieving success. Especially when you follow your rescue plan. Or rescue plan for rescue plan. In my case I just wanted to have a car working by the morning.
  • Very often it’s not about your own, but others’ constraints. I don’t have two spare rims in my garage. I can’t fix damaged rim by myself. I have to base on other people. And their working hours too.
  • You can get additional help but usually not for free. I borrowed my wife’s car but I was expected to pick her up when she finished her workday. I convinced guy in local garage to fix the rim but I had to be back exactly when he was closing and not a minute later.
  • Rescue plan always bring additional costs. You can count money I left at local garage and local dealer but you should also count whole day wasted just to bring the car back to the shape from the morning. And yes I had other plans in mind which quickly became former plans.

But after all, I drove to the work today, which means projects can be rescued with enough effort put in, some experience in dealing with unexpected situations and a helping hand from others. Even when we make a number of failed assumptions. Sounds pretty optimistic, doesn’t it?

in: project management

2 comments… add one

  • Le Do Hoang Long November 5, 2011, 3:04 am

    Nice story and good lesson. But I have read that “unconscious assumptions” are the tools the save our brain from concerning too much. Trying to think ahead sometimes is impossible, you know…

  • Pawel Brodzinski November 5, 2011, 3:13 am

    Of course, we can’t possibly analyze every possible situation. Perfection, in any area, is infinitely expensive, so we always cut corners.

    The goal is to understand the mechanism and to operate it consciously. Especially when it comes to assumptions we can easily verify and at the same time they can bring huge additional cost if we are wrong.

    The story just shows how many assumptions we make unconsciously and how many of them can appear to be totally wrong when things get ugly. All in all I dealt with the issue and it cost me only a day (and some money), so it definitely wasn’t a huge crisis. Yet quite a good lesson I’d say.

Leave a Comment