Montgomery schools’ executive director for operations, said its enrollment projections are about 99 percent accurate at a county level.

...Essie McGuire, Montgomery schools’ executive director for operations, said its enrollment projections are about 99 percent accurate at a county level. But she said the countywide calculations have masked changes in individual neighborhoods. Statistically speaking, she said, it’s also more difficult to predict the future at a more detailed school level.

The school system recently hired a consulting group to help update its enrollment forecasting models and respond more quickly to rapid changes, particularly in high-growth areas...

https://www.washingtonpost.com/local/trafficandcommuting/as-school-systems-grapple-with-overcrowding-parents-wonder-why-enrollment-projections-are-so-off/2018/09/09/7f8abda4-95cd-11e8-810c-5fa705927d54_story.html?noredirect=on&utm_term=.84dd12cebecd