I know that various dog breeds have different life expectancies. Has there been research done on specifically the Yorkshire Terrier breed?
The average life expectancy for standard size Yorkies is 13-16 years; 14.5 is the median age. The average life expectancy for females is a little longer than it is for male's (1.5 years longer).
It's important to note though that teacup Yorkie's (those under 4lbs) have a shorter lifespan - just 7-9 years on average. This is largely due to the fact that they're at increased risk for traumatic injury due to their small size.
The Yorkie Info Center offers more information on the research that's been conducted, specific to this breed.