The q-q plot for the data in Table 2 is shown in the left frame of Figure 11.
In general, what should we take as the corresponding theoretical quantiles? Let the cumulative distribution function of the normal density be denoted by Φ(z). In the previous example, Φ(-1.28) = 0.10 and Φ(0.00) = 0.50. Using the quantile notation, if ξq is the qth quantile of a normal distribution, then
Φ(ξq)= q.