Cross Validated A very active question and answer site for statisticians, machine teachers, data analysts, data miners and data visualization experts operated through the Stack Exchange network of Q&A sites.
Data Colada Critiques of p-values and other statistical practices in the social sciences, by University of Pennsylvania Wharton School professor Uri Simonsohn.
Error Statistics Philosophy On the foundations of frequentist statistics, by Virginia Tech philosophy professor Deborah G. Mayo
Normal Deviate Thoughts on statistics and machine learning, by Carnegie Mellon statistics professor Larry Wasserman
One R Tip a Day from Italy
Probably Overthinking It Statistics blog on Bayesian analysis, Python and other topics, by Allen Downey
Probability and Statistics Blog `In Monte Carlo we trust’ by statistician Matt Asher
R-bloggers R news and tutorials contributed by 400+ R bloggers, a blog aggregator by Israeli statistics student Tal Galili
R-statistics Writing about statistics with R and open source stuff (software, data, community) by Israeli statistics student Tal Galili
Radford Neal’s blog Discussion of the underpinnings of R and other issues in computational statistics
Revolutions Open source R for big data analytics, predictive modeling, data science and more from the staff of Revolution Analytics.
Simply Statistics by three biostatistics professors at Johns Hopkins University
Statistical Modeling, Causal Inference, and Social Science by Columbia University statistics and political science professor Andrew Gelman and friends
Stats Chat by University of Auckland statistician Thomas Lumley
Xi’an’s Og About R, statistics and other topics, by Université Paris Dauphine statistics professor Christian Robert