Here's the way Yahoo determines the way they're going to show the dividend and its yield (actually, it's the way Reuters does it and Yahoo gets it from Reuters).
It's a bit complicated and not the way the rest of the world does it. They are trying to get at a recurring rate.
So, here's the rules:
1) If the stocks dividend has been different for the last 3 quarters (for example, if it's increased every quarter), they will use the sum of the last 4 quarters (they assume it's not recurring and not stable, regardless of the fact that it's only been increasing in most cases).
2) If 2 of the last three dividends were the same, they will annualize that number and use it to calculate the yield. (again, assuming it's recurring and stable).
I don't know why Yahoo is screwing up PZN's yield. They should be showing $0.48 x 4 = $1.84. It must be related to the merger. Maybe the CUSIP number changed or something.
Who cares, anyway? Anyone who studies the stock will learn the value of the business. People who are investing because they see a stock yielding 12% and they know nothing about it will only add volatility and risk to the stock.
My $0.02. Hope it's useful. Buy it, stick it away and forget about it.