def standard_variance(data, period):
catch_errors.check_for_period_error(data, period)<EOL>sv = [np.var(data[idx+<NUM_LIT:1>-period:idx+<NUM_LIT:1>], ddof=<NUM_LIT:1>) for idx in range(period-<NUM_LIT:1>, len(data))]<EOL>sv = fill_for_noncomputable_vals(data, sv)<EOL>return sv<EOL>
Standard Variance.

Formula:
(Ct - AVGt)^2 / N