diff --git a/source/statistics/metrics.rst b/source/statistics/metrics.rst
index 4e7c51d..c86ef8a 100644
--- a/source/statistics/metrics.rst
+++ b/source/statistics/metrics.rst
@@ -122,7 +122,7 @@ When computing the standard deviation of :math:`X`, we have:
   s^2=\frac{\sum_{i=0}^n (x_i-\overline{x})^2}{n}
 
 In this case, the degree of freedom is :math:`n-1`. As the mean is already known, only :math:`n-1`
-of the :math:`x_i` are allowed to vary. By knowing :math:`n-1` of the :math:`x_i`, we can deduce the last
+of the :math:`x_i` are allowed to vary. In fact, by knowing :math:`n-1` of the :math:`x_i`, we can deduce the last
 one as follow:
 
 .. math::