What is computational reproducibility?
When you load data into an application like Excel, you click through a series of options to clean up or organize and then visualize your data. If you wanted to repeat this process, you would have to manually go through the same series of steps over and over again, which is a lot of mouse clicking. It's also very difficult to communicate your workflow from raw data to visualization as you would have to write down every step and do so in a way that was clear enough for someone else to reproduce exactly.
Working in a scripted programming language like R, instead of clicking buttons, we write code that tells the program how to clean, organize, and then visualize our data. When we want to repeat the process, we just run our script - or mini program - and it exactly, computationally, reproduces our workflow. It's less work for us and it's reproducible. And, since anyone we share our script with can read our script to see the steps taken to go from raw data to visualization, it's transparent. We just don't get this level of reproducibility and transparency with Excel.