Brand      Observation     Before  After  Difference
A               1           8.6     7.9     0.7
A               2           9.4     8.7     0.7
A               3            10     9.2     0.8
A               4           9.2     8.4     0.8
B               1           9.2     8.1     1.1
B               2           9.2     7.8     1.4
B               3           8.8     7.5     1.3
B               4           9.4     8.2     1.2