ELI5: Optimizing the Critical Path
If you're familiar with Reddit, you will most likely have heard about ELI5: Explain Like I'm Five. It is an attempt to explain complicated concepts that would not be understood by most people when explained by experts in language they speak in when speaking to their peers.
I thought of something I could ELI5 today. Of course, because it is ELI5, it will not be testing your knowledge if you already know something about it, and of course, some of the experts out there will even find flaws in what I explain today, but here goes, in an example of my everyday life:
What is a Critical Path in a project?
In short, it is the longest path of sequenced events from the start to the completion of a project. The example below is really not an example of an advanced project, but it is a "project" that most people go through on a daily basis, in some form or another.
Project Cease The Day
In order to make the most of your day, you need to get it to start right. For me, that start usually looks something like this: have a nice cup of coffee and a breakfast. Yours may be different, but please, humor me. Let's pretend that this is an amazing project, and that you need to plan this JUST right in order for you to consider your day "ceased".
The broad steps I need to take:
Now - everyone makes their coffee different and eats a different breakfast (or not eat breakfast at all), but, let's optimize this in terms of what this project looks like for me, all optional steps included:
TOTAL: 810 seconds (13.5 minutes).
The Critical Path in this process are steps 1 to 16. In order to complete this project, all 16 steps are done. The optional ones 3, 4, 12, 13 and 14 can be cut in some cases, but we're doing them in this case. These optional items do not typically affect the outcome of the project by much, and can be left out if needed, given a fixed set of constraints such as time and budget. But let's assume that we are able to do all these steps.
Sometimes, by optimizing the process, you can achieve all the steps which would sometimes not be possible. Optimizing the process also sometimes allows you to factor in circumstances outside of your control, such as Load Shedding. Let's throw in one of these into our project:
(For the readers not in South Africa who do not know what Loads Shedding is, well, be glad you don't have to experience it. If you search Google for "what is load shedding" the side bar of Google might tell you about the "South African energy crisis". Delightful reading...)
Let the optimization begin!
If we do these tasks in the order I have done them originally, it means we have spent 810 seconds (13.5 minutes) on this project, assuming there were no delays otherwise.
With the critical path processes optimized for the given scenario, it may look something like this now:
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1. Get the cup from the cupboard - 10 seconds
2. Fetch the milk from the fridge and put milk in cup (optional) - 15 seconds
3. Heat milk in microwave (optional) - 60 seconds
Now, while the microwave is running, and you are not do anything else for that 60 seconds, so you can save time by doing the following short duration steps during that time - processes running in parallel:
By this time, the milk in the microwave is just about finished heating milk up for our coffee, so we have saved 55 seconds in our critical path.
9. The moment the milk heating is complete, we switch on the kettle, this would take 120 seconds to complete. We can switch the kettle on now, because the microwave is finished, and we will not trip our electricity with overload.
While the kettle is boiling for 120 seconds, we can do a few more things in our idle time:
10. Put coffee in the cup - 10 seconds
11. Put sugar in the cup - 10 seconds
12. Give the dog some food and water - 90 seconds
By this time, the kettle will be just about done boiling, and you can finish up the routine, and we saved ourselves another 110 seconds, give or take:
14. Pour hot water into cup and stir - 20 seconds
15. Pour hot water over cereal - 10 seconds
16. Drink coffee - 160 seconds
17. Eat breakfast - 240 seconds
So - our process order has changed, and got some reorganization (we now have 17 processes, not 16) and some insignificant details changed in the constitution of some of the tasks, but in essence, we've optimized our process quite a bit. The total time we've spent now in our Cease the Day project is a mere 645 seconds, or just about 10.75 minutes. This means that we have saved ourselves about 3 minutes in the morning by optimizing this process, a saving of about 21%, or 165 seconds.
Of course, there is a lot more ways to optimize this process even further, but we don't want people to think you're a freak now, do we?