More About Tallying The World's Planetarium Attendance
by Mark C. Petersen, Loch Ness Productions
"There are lies, damned lies, and statistics."
-- Mark Twain, misquoting Benjamin Disraeli.
I get messages like this occasionally:
It is interesting to read your current tally of attendance at the
world's planetariums. It would be interesting to compare this number to
previous year's tallies. Seeing numbers from previous years, especially
from a source using the same method, would enable trends to be observed.
Such trends would be as important as the number for this year.
Could you post a comparison?
I could, but I would not want to claim trends could be observed, because of the methodology (or lack thereof) involved.
Nov 1995: Each year 75,374,791 people visit the 2613 planetaria of the world.
Feb 1996: Each year 73,950,856 people visit the 2633 planetaria of the world.
Aug 1996: Each year 88,121,010 people visit the 2666 planetaria of the world.
Oct 1998: Each year 95,973,089 people visit the 2814 planetaria of the world.
May 1999: Each year 94,461,735 people visit the 2820 planetaria of the world.
Sep 1999: Each year 86,311,550 people visit the 2831 planetaria of the world.
Jul 2000: Each year 92,722,498 people visit the 2513 planetaria of the world.
Apr 2001: Each year 91,909,259 people visit the 2595 planetaria of the world.
Feb 2002: Each year 89,874,837 people visit the 2565 planetaria of the world.
Jul 2002: Each year 87,647,899 people visit the 2571 planetaria of the world.
Sep 2002: Each year 90,372,347 people visit the 2959 planetaria of the world.
May 2003: Each year 91,856,051 people visit the 2983 planetaria of the world.
Jan 2004: Each year 93,861,486 people visit the 3010 planetaria of the world.
Aug 2004: Each year 93,541,675 people visit the 3015 planetaria of the world.
Mar 2005: Each year 102,348,153 people visit the 3020 planetaria of the world.
Mar 2006: Each year 103,310,448 people visit the 3170 planetaria of the world.
Mar 2007: Each year 108,461,686 people visit the 3282 planetaria of the world.
Mar 2008: Each year 110,921,345 people visit the 3341 planetaria of the world.
When I post a new attendance tally here on the Web site, it overwrites the old. I was able to capture the comparison above by doing a Google search on the newsgroup sci.astro.planetarium with a keyword of "Tallying". Fortunately I was consistent in my subject titles.
In my database, each dome theater record has one data field for "Annual Attendance". When a figure is provided to me, I enter it -- and it wipes out previous data (if any) that was there. When I generate the attendance projection, it is merely a snapshot of the state of the database at that time. Moreover, I do NOT keep track of the year for which the attendance figure is given. If the figure for 1995 is the last one I received, that's what gets used for the rest of eternity, because that's all I have to work with. It was valid once, anyway <g>. I do not wipe out the data each year and start over with a clean slate. My projection is based on accumulated, not yearly data. In 2005, I did start keeping track of the year the attendance report was received, so in the future, I might be able to set a filter for, say, recently received reports only.
Also, keep in mind I'm using volunteered data (from you kind volunteers out there). An accumulated base of 15% isn't exactly comprehensive, though pollsters frequently project from far smaller samples. On the other hand, to my knowledge there are no other such tallies available; I daresay this guess is as good as you're likely to find. It wouldn't hurt to have more data points, of course!
Additionally, my counting program has evolved a little over the years, and there have been some anomalies that have caused the totals (and planetarium count) to bounce around some. For example, some time ago, I had entered an international planetarium's attendance figure of 50,000 -- but the planetarium itself had an unknown dome size in my database. Based on that one data point, the program estimated that every "unknown" dome size had an average attendance of 50,000, which was clearly not the case -- but it inflated the projection by more than 10 million people! Woops. Then, in trying to correct it, I simply rewrote the program to leave out facilities for which the dome size was unknown. Woops again; those facilities were then dropped from the planetarium count altogether; it was just the attendance figure that should have been omitted.
In September 2002, one sole attendance report had a significant impact. One large U. S. facility reported an annual attendance of 1.2 million people (if you have to ask, you haven't been paying attention <g>). This skewed the average for the size category from 220,000 up to more than 320,000; and thus the projection for that category by nearly 1 million people. Would that every 21-meter dome have such great attendance!
In 2005, I restructured my database, and separated out institutions from the domes they operate. Before, if an institution was operating multiple dome theaters (portables, for example), their total attendance had been counted for their large, fixed theater dome size. So, I re-defined the term "planetarium" to mean the dome(s) instead of the singular institution. Then I discovered that I'd been using a fixed-dome theater's attendance report count for any portables they operated, too; in other words, the number of responses for the latter category had been getting over-counted. Now the figure for "Responses" in those small size categories (portables are all in the 5-7 meter diameter range) is more correct. But, the average (total visitors divided by responses) became a much larger figure, and when multiplied by the large number of domes of that size, the projected attendance for that category tripled. This significantly boosted the bottom line attendance projection by some 7 million. One cannot conclude that worldwide attendance increased so much from the previous report; the estimating method became more refined.
In summary, then, I wouldn't feel comfortable saying there's a "trend" in attendance one way or the other. The most I can report is, some are up, some are down, most are within the error bars for maintaining. I cannot say with certainty (like Ann Taylor does on NPR): "Declines led advances by a margin of 3 to 2".
On the other hand, while some older facilities are closing down, others are renovating and new theaters are being built. I think we can safely say with certainty that the planetarium field is not moribund.
|
