> How can you possibly be arguing that we should not be testing models with all available data? I'm not arguing that at all? I'm pointing out that this is good

> How can you possibly be arguing that we should not be testing models with all available data? I'm not arguing that at all? I'm pointing out that this is good, but is rarely what is meant with 'big data'. In my experience with 'big data' in silicon valley, it refers to the constrcution of black box algorithms, rather than 'operations research' or 'statistics' which involve fitting data to a model determined via another process.