diff --git a/education/statistics/Measurement Error.md b/education/statistics/Measurement Error.md
index a6848ea..aef63e9 100644
--- a/education/statistics/Measurement Error.md	
+++ b/education/statistics/Measurement Error.md	
@@ -13,9 +13,10 @@ $$ IndividualMeasurement = ExactValue + ChanceError $$
 # Outliers
 Histograms of repeated measurements tend to follow the normal curve.
 
-According to the empirical rule, 99.7% of such measurements should be within 3σ of the exact value. 
+According to the empirical rule, 99.7% of such measurements should be  +-3σ of the exact value. Measurements that are not within 3σ are considered *outliers*. 
+
+Removing outliers reduces σ.
 
-$$ $
 # Terminology
 | Term | Definition |
 | -- | -- |
diff --git a/education/statistics/TODO.md b/education/statistics/TODO.md
new file mode 100644
index 0000000..3b87a9f
--- /dev/null
+++ b/education/statistics/TODO.md
@@ -0,0 +1,2 @@
+(Chapter 7, STAT 1040)
+