Structural Equations

In terms of EQS, the following linear equations apply:
$$\begin{align*}V_1 &= V_1\\ V_2 &= F'_1 - V_2 + V_2\\ V_3 &= F'_1 - V_2 + V_3... ..._4 &= F'_1 - 2V_2 + V_4\\ V_5 &= F'_1 - 2V_2 + V_5\\ V_6 &= V_6 \end{align*}$$
The constrains are the same as in the model described above. This model, however, is mathematically equivalent to the previous model, as F'₁ can be written as V₁ + F₁. This means that by using EQS one cannot make a distinction between the simpler Erlang model and the Poisson-Erlang model. Both models give the same results. In order to make it possible to decide between both models, a different method was used, in which predicted third central moments were compared to observed third central moments.