The Problem
When Redfin was smaller, a lot of planning was possible using basic models implemented via spreadsheets and gathering input via email or files saved to GoogleDrive. But, as we wanted to make models more complex, and scale these models to handle our business’s increased scope, we found those things simply wouldn’t work anymore. We found ourselves unable to use more statistical approaches to forecasting that don’t work in spreadsheets, maintaining the formulas was error-prone and slow, and the amount of time spent on consolidating user input limited the number of iterations we could run of our models. Workbooks took too long to update with refreshed data and then would be painfully slow, taking 10 or more minutes for people to open and actually use, or worse: crashing, leaving them unable to open them at all.