Comment Re:Good god... (Score 1) 676
Again, you have clearly no idea what you're talking about. I'd advise you to stop blustering and get more than a Masters level education in statistics.
Nowhere does the article claim that calibration is "twisting the data" or "changing the data". It quite clearly says that calibration is changing the values of variables used in the model: "Calibrating a complex model for which parameters can't be directly measured usually involves taking historical data, and, enlisting various computational techniques, adjusting the parameters so that the model would have 'predicted' that historical data."
What the article is describing is fitting a model: finding parameter values that cause it to fit the data.
"Calibration" is a commonly used statistics term in some sub-disciplines. (Others call it "fitting", "tuning", or "parameter estimation".) It literally means "fitting the model", or in a Bayesian context, computing a posterior distribution over the model parameters (e.g., this discussion).
It is simply false that a model which validates well on out-of-sample data will necessarily predict well. The article is in fact about circumstances under which this assumption does NOT hold, such as in statistically non-identifiable models.
One way in which this can happen is if your likelihood surface (or, more generally, objective function or error metric) is multimodal. It can easily happen that both your training data and validation data identify the same mode, but the true value ends up being a different mode, and you can only find that out farther into the future.
To understand better what the article is talking about, you may want to read this paper, which I suspect is by the same guy cited in TFA.
And yes, I do build statistical models for a living. Pretty much everything I do on a daily basis is model calibration. I am not a card-carrying statistician myself (i.e. my Ph.D. is not in statistics), but I'm trained in the field, all of my research is in statistics, I collaborate regularly with statisticians, and publish research in statistics journals.