# Doing Is Normally Distributed, Learning Is Log-Normal - hiandrewquinn.github.io Synced: [[2024_05_30]] 8:29 AM Last Highlighted: [[2024_05_29]]  Summary: Learning processes follow a log-normal distribution, while doing is normally distributed. Software estimation struggles with recognizing non-normally distributed learning. The concept of a leaky pipeline sheds light on challenges in software development and emphasizes the importance of relevant experience and specific tooling knowledge. ## Highlights [[2024_05_29]] [View Highlight](https://read.readwise.io/read/01hz15q8g32rzz6hwwy2c7g68p) > Say you’re working on a Laravel web app. You’re about 90% sure you know how to start the app. You’re 80% sure you know how to handle the infra you’ll need to get it online. And you’re 70% sure you know how to get your first customer. What is your chance of successfully going from zero to first customer? 0.9 * 0.8 * 0.7 = a little over 0.5. That’s … a lot less encouraging than any of the previous numbers, if you buy my multi-step modelling. [[2024_05_29]] [View Highlight](https://read.readwise.io/read/01hz15pd4r9tfqp94estexphwz) > Everything we know about traditional project management, from Waterfall to Gantt charts to estimation practices, are on some level based around the idea that each individual step in the chain is bell-shaped: A process taking twice as long as it normally does might be 2 standard deviations out, aka in the bottom 2.5% of outcomes. But in a log-normal distribution, processes taking two, three, or five times as long are much more common, and this throws things into disarray. Some things happen much faster than usual - but doing one estimated week-long project in half the time, and another estimated week-long project in twice the time, still leaves you in the red for your time budget. [[2024_05_29]] [View Highlight](https://read.readwise.io/read/01hz15nbxzdawckpw32jn8jdk0) > Needless to say, it is almost never the case that in software development you know all or even most of the technical hurdles you will face in the processs of development. An [efficient markets hypothesis](https://en.wikipedia.org/wiki/Efficient-market_hypothesis) fanboy might say “If anyone already knew how to do it, it would already be done by now”. [[2024_05_29]] [View Highlight](https://read.readwise.io/read/01hz15m5swrejww2xjshyh68km) > Now what’s really interesting about this theory is that it suggests that **business processes that are normally-distributed are the exception, not the norm**, in a sense. *Every* new process a person has to undertake will have at least some phase which is dominated by learning.