One of the questions that often gets asked is whether a given pollster generally delivers a higher vote estimate for a party than other pollsters – basically, whether a polling firm such as, say, Newspoll (to choose a random polling organisation), leans
towards one party or the other.
We can never really tell if any pollster delivers results that are actually
higher or lower for a party than other pollsters, because we just don’t have elections every week to determine the true state of public opinion with which to judge them against. However, we can look at relative leans – how pollsters lean for or against a party on the vote estimates compared to what other pollsters are doing at the same time.
It doesn’t tell us who is more accurate – and that’s an important factoid
to keep in your thought orbit here - but rather, it tells us how pollsters behave comparatively to each other.
To get us into the groove - and something you may not have seen in a while - this is how the primary vote estimates and the two party preferred vote estimates look like since September 2010 for the four public pollsters we regularly track. Click to expand each chart