What is the average wage increase and how does one calculate it? Gottfries (2013, p. 166) refers to the following formula as the "average wage increase:"
$$\frac{\Delta W_t}{W_{t-1}}$$
If the above formula is meaningful, then my question is more a clarification about terminology and notation.
As to terminology, what is a more popular way to refer to this equation other than the average wage increase?
As to notation, Gottfries refers to $W$ as the "average wage level," but what do the other symbols mean? Is it safe to assume the expressions $W_t$ and $W_{t-1}$ refer, respectively, to the average wage levels at times $t$ and $t-1$? What then does $\Delta W_t$ represent? Is $\Delta W_t$ the difference in average wage levels at times $t$ and $t-1$ (i.e., $\Delta W_t = W_t - W_{t-1}$)?
I think this question is worth asking since 1) there has to be a more popular way to refer to this equation (Gottfries book was all that came up when I Googled "average wage increase") and 2) I don't want to assume, as far as notation goes, more than I have to (Gottfries doesn't define these symbols).