# Why I version control all of my analysis and data science work

Earlier this year I took the steps to get our small team set up on Github. We don’t have have a large team of engineers or data scientists yet, but I think it’s important to lay the ground work now. Sometimes it seems like our world is split into two types of people: Those who know/love git and use it daily and those who don’t.

Unlike a large open-source project, I mainly use Github for myself right now. Each analysis that I do uses Github Flow and gets it’s own private repository. I find this much better than putting all of my work into one repo, like what 538 does.

## How

Just like with any open-source project, every time I work on a project, I’ll start out by creating issues of all of the work that I want to do. I’ll create forks to work on those specific issues, then I’ll create pull requests to close those issues out. This helps me keep track of changes that I make and gives me some digital ‘breadcrumbs’ for what I was thinking when I was going through this process. I’ve resolved not to commit directly to the master branch unless I’m fixing something very small like a typo, which should have been caught while doing a pull request.

For data, it depends on how often the data are changing. Here’s my thinking:

1. If the data are larger than 100 mb it will be kept in cloud storage. Github has limits on how large uploaded files are.
2. If the data are constantly changing, it stays in our data warehouse (We love BigQuery!!). I’ll use bigrquery. The data may be given a specific dataset and table for long term storage.

Before I begin my analysis, I’ll figure these things out and then make notes of them in my README file.

## Why

First and foremost, I want to be as precise as possible. Versioning my work lets me walk back through my code in the future to see what I did and what I was thinking at the time. I’ll admit that I’m getting better with my commit messages. I’ve worked really hard from being lazy and just using updating files to being more precise about what changed.

Second, I want my work to be reproducible. I never know who will need to rerun my analysis in the future and I want it to be as easy on me or them as possible. I should take this even further and package everything up in a docker file so that in the future you have the same version of R and packages, but I’ll come back to that at another point in time.

Third, it teaches you discipline and process, something that everyone could use more of. Is it pedantic and tedious? OF COURSE But it works and it works well. This is one reason why companies like Starbucks are successful. You can go to any store and get the same cup of coffee 99.99% of the time.