<p dir="auto">You guys seem to be using np.std(x) to scale each column instead of np.std(x, ddof=1). As a result your std estimate is biased.  Note that similar function in R, base::scale uses unbiased std estimate.</p>
<h4 dir="auto">Description</h4>
<p dir="auto">It would be nice to provide StandardScaler with an option to chose unbiased estimator of variance,</p>
<p dir="auto">It it sometimes convenient to use unbiased estimator of variance: numpy.var(X, ddof=1)<br>
instead of default: numpy.var(X, ddof=0)</p>
<p dir="auto">So far StandardScaler does not allow to set ddof.</p>
<h4 dir="auto">Versions</h4>
<p dir="auto">Linux-4.4.0-45-generic-x86_64-with-Ubuntu-16.04-xenial<br>
('Python', '2.7.12 (default, Jul  1 2016, 15:12:24) \n[GCC 5.4.0 20160609]')<br>
('NumPy', '1.11.2')<br>
('SciPy', '0.18.1')<br>
('Scikit-Learn', '0.19.dev0')</p>