Hence, b1 represents the difference between the means of the low-dose group and the placebo
group. This form of dummy variable coding is the simplest form, but as we will see
later, there are other ways in which variables can be coded to test specific hypotheses. These
alternative coding schemes are known as contrasts (see section 10.2.11.2). The idea behind
contrasts is that you code the dummy variables in such a way that the b-values represent
differences between groups that you are interested in testing.