I would have thought that we’d plowed the faddish field of the creative economy enough by now.

But no. Judging by the data released Monday by the city’s Office of Arts, Culture and the Creative Economy, we’ve only begun to document whether the creative sector can become a growth engine for the city.

With a three-year, $75,000 grant from the William Penn Foundation, the office bought data from the Western States Arts Federation to benchmark where the city and region stand using an index.

It’s called the Creative Vitality Index, and the group known as Westaf developed it several years ago to provide a measure of the relative strength of a region’s creative sector against a national baseline of 1.00. A score above 1.00 indicates strength, while anything below that level is a sign of weakness.

It was encouraging to hear Gary P. Steuer, the city’s chief cultural officer, say that index uses a very narrow definition for the creative economy: just 36 occupational categories.

What has tarnished previous statistical studies is their inclusion of other “knowledge industries,” such as software developers and biotechnology researchers. There’s far more science than art involved in the products they create.

Fashion designers, actors, dancers, musicians, and singers are undeniably creative. Animators, camera operators, sound engineering technicians, and performers’ agents and business managers are integral, too. I might quibble with the inclusion of librarians, but the bulk of the list, available at this link to a PDF of the report, seems to reflect what most of us consider creative work.

The index consists of two parts: employment in the arts, and community participation in them through recipients of that consumer spending.

Philadelphia’s strength is the revenue generated by the nonprofit arts groups and other cultural institutions that incorporate the arts into their activities, such as museums and performing-arts schools. For example, Philadelphia nonprofit arts organizations generated 2008 revenue of $347 million, or $239.74 on a per-capita basis. That was good enough for an indexed score of 5.02, or five times the national baseline.

Sales of books, recorded music, and photographic equipment are incorporated by the Creative Vitality Index. But it doesn’t include online purchases. Thus, the data document declines in sales at bricks-and-mortar outlets in the region, but can’t tell us whether Philadelphians buy more music over iTunes than do Bostonians or New Yorkers.

Employment accounted for 40 percent of the overall index. Good thing, too, because that was clearly a weakness for the city. In all, 17,699 people were employed in 2008 in the 36 occupations that make up the creative sector - from 36 musical-instrument repairers and tuners to 1,843 public-relations specialists.

Total employment is down from 17,799 in 2006 and up from 17,680 in 2007. But the indexed score of 0.85 means that employment in the city is 15 percent below the national level.

Given that 2008 was a recession year, Steuer said, he considered it a positive that employment held steady. But when the next batch of data becomes available in the spring, it’s quite likely Philadelphia could post a decline in creative jobs.

The city’s arts office proudly stated that the overall Creative Vitality Index for 2008 showed Philadelphia with a 1.70 score, indicating the city’s creative sector was 70 percent stronger than the nation’s as a whole.

For an 11-county Philadelphia region, the CVI score was 1.11, putting the region 16th on a list of metropolitan areas with vibrant creative sectors. I would not have guessed that No. 1 was the Washington area, with a score of 2.52. My money was on Los Angeles (No. 2 with a CVI of 2.32) or New York (No. 3 at 2.20).

(Steuer said the city could not compare itself against other cities, because the data are collected only at the county level.)

Alan Greenberger, deputy mayor for planning and economic development, called the creative sector “absolutely vital to the economic base of the city.”

At 17,699 jobs in a city where 556,523 were employed in October, that’s overstating the impact of the creative economy for most Philadelphians.

Is the creative economy more vital than the city’s gargantuan health-care and education sectors? How about professional and business services, the highest-paying sector?

Probably not. But there is no question the public gets much more excited over a new movie about a maverick lawyer or a play about a miraculous medical advance than possible changes in city, state, and federal policies that may encourage or discourage activity in those real-life professions.