Very true, Sal, about joggers and articles with stretch.
I don't know if the NZ and Australian makers are doing this, but in addition to the size charts, it can help to look at the item measurements (when these are given). They are not always available but where they are, can be extremely informative.
I also correspond with customer service and ask questions, especially if I already own something from that maker -- I tell them what size and how it fits and ask "Is the fit of this item similar?". Their guesstimates are not always perfect, but they have been helpful on occasion.