A place for beginners to ask stupid questions and for experts to help them! /r/Machine learning is a great subreddit, but it is for interesting articles and news related to machine learning. Here, you can feel free to ask any question regarding machine learning.
Business Intelligence is the process of utilizing organizational data, technology, analytics, and the knowledge of subject matter experts to create data-driven decisions via dashboards, reports, alerts, and ad-hoc analysis.
A place for visual representations of data: Graphs, charts, maps, etc. DataIsBeautiful is for visualizations that effectively convey information. Aesthetics are an important part of information visualization, but pretty pictures are not the aim of this subreddit.
A place for redditors/serious people to discuss quantitative trading, statistical methods, econometrics, programming, implementation, automated strategies and bounce ideas off each other for constructive criticism, feel free to submit papers/links of things you find interesting.