minor fix bughunt reg1 py issue

source/regression1.Rmd

@@ -107,7 +107,7 @@ is that we are now predicting numerical variables instead of categorical variabl
 
 > **Note:** You can usually tell whether a\index{categorical variable}\index{numerical variable} variable is numerical or
 > categorical—and therefore whether you need to perform regression or
-> classification—by taking two response variables X and Y from your data,
+> classification—by taking the response variable for two observations X and Y from your data,
 > and asking the question, "is response variable X *more* than response
 > variable Y?" If the variable is categorical, the question will make no sense.
 > (Is blue more than red?  Is benign more than malignant?) If the variable is