STEAMBOAT SPRINGS — The first thing to know about demography and projecting future population growth is that it is not a science — it is more of an art.

Over the past five years, the Steamboat Springs School District commissioned three demographic reports.

Finance Director Mark Rydberg, who is responsible for forecasting his own student enrollment count at each grade level for budgeting purposes, said the demographic reports are one of many tools he uses.

And, he points out, demography uses past performance to predict future results. Relying on historical patterns sometimes works and sometimes doesn’t, he said.

“All the studies have their strengths and weaknesses.” Predicting long term — 15 to 20 years out — “You just don’t know,” he said.

Birth rates are a key component in K-12 demography, and they are important, Rydberg said. But when it comes to Steamboat Springs, trends show they aren’t everything, he said. Birth rates can be useful in predicting how many new kindergarten students will enroll, but they don’t help predict how many students will be added or subtracted over time.

In his enrollment projections, Rydberg also takes into consideration how many 4-year-olds are in the community and spring preregistration numbers.

There is also the “cohort comparison rate,” which identifies the growth rate for any given grade by comparing it with the lower grade from the previous year.

For example, for the 2014-15 school year, there were 193 ninth-graders. When that group moved to 10th grade, there were 187 (2015-16). The next year, there were 190 11th graders (2016-17). That number then jumped to 201 as that same class entered 12th grade.

And that’s unusual, Rydberg said, to see such a jump from 11th to 12th grade. And hard to predict.

Rydberg points to a chart (see graph) showing how many students were added to each cohort, or graduating class, from first through 12th grade. For Rydberg, this illustrates one of the biggest prediction challenges for the district: How many families are moving here from other districts and enrolling their kids, how old are those kids when they move here, and how do you predict how many families will continue to move here? And, how many will leave?

The most recent demographic report, by RSP & Associates, took a more comprehensive report and also incorporated the potential impact of new or planned housing developments.

And there are a number of other characteristics unique to Steamboat that may or may not be factored in.

For example, the opening of the Mountain Valley Montessori Charter School in 2016 had an impact on enrollment and the projections. The first report came out before Montessori opened. The second was finished the same year Montessori opened, though that demographer was under the impression the school would be K-8, when it ended up being K-5.

In Rydberg’s analysis of the various reports, “They all show we are growing.”

Some projections are high, some a little low. Some may overestimate growth at the high school level while underestimating growth in elementary school.

“Somewhere in the middle is where we are going to be,” Ryberg said.

To reach Kari Dequine Harden, call 970-871-4205, email kharden@SteamboatPilot.com or follow her on Twitter @kariharden.

To reach Kari Dequine Harden, call 970-871-4205, email kharden@SteamboatPilot.com or follow her on Twitter @kariharden.