This document discusses enrollment cyclicality in the Katonah-Lewisboro school district. It notes that the district has historically experienced peaks and troughs in kindergarten, total student, and senior enrollment every 20-30 years due to the unique demographics of the affluent suburb of Lewisboro. The last enrollment peak was in the mid-1970s, with a trough in the mid-1980s. The document projects that based on this cyclical pattern, the district should expect another enrollment peak within the next 5-10 years. It questions what plans the district has to handle the anticipated peak and how it will manage periods of lower enrollment.

1. KATONAH-LEWISBORO DISTRICT:
ESTIMATING THE IMPACT OF
ENROLLMENT CYCLICALITY

2. 2
Lewisboro is a Unique Place
• Lewisboro is an “Aspirational Family Community”, an affluent suburb of
New York City
• Lewisboro has unique characteristics:
a) High Median Household Income
b) Excellent Education System
c) High Taxes
d) High Cost of Living
• Because of this, Lewisboro has historically exhibited much more extreme
Age-Sex demographics than a self-sustaining population, and more
extreme demographics than the greater suburban Westchester region
• Lewisboro derives much of its population from a cycle of family
replacement: Affluent young families from New York City buy homes from
empty-nesters and retirees (confirmed by top real estate brokers by market share in Northern
Westchester county)

3. 3
Age-Sex Pyramids
New York State
New York City
Westchester County
Lewisboro
The national and state average representation of the 20-30 year old group is about 14%.
Westchester, as a suburb of New York City, has less, at 11%.

4. 4
Lewisboro: An Aspirational Family Community
Lewisboro: 1970 & 1980
Lewisboro 2000
Lewisboro: 1990
Lewisboro: 2010
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Since 1970, Lewisboro has always had a population of 20-30 year olds less than 6%. The
community has always relied on young families replacing empty-nesters and retirees.

5. 5
Enrollment Cyclicality
• As a result of this unique community dynamic, Lewisboro has
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historically experienced cyclical enrollment
The peak of the last enrollment cycle occurred in the mid1970s, and the district reached a trough level of enrollment in
the mid-1980s
The cycle has three different points to measure:
A) Peak and Trough Kindergarten Enrollment
B) Peak and Trough Total Student Enrollment
C) Peak and Trough Senior Enrollment
The school system has historically experienced very large
swings in Elementary enrollment and total student enrollment
Enrollment cyclicality presents unique challenges for
managing school capacity

6. 6
Peak & Trough Enrollment
• Trough Kindergarten Enrollment will trail Peak Student
Enrollment by 8-12 years, due to overlap of demographic
age populations and the fact that
• Peak Kindergarten Enrollment will lead Peak Student
Enrollment by 8-12 years
• This leading / lagging dynamic is due to the cyclicality of
the age demographic and aging of the student body
School Year Ending
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
Kindergarten Enrollment
330
308
288
301
329
300
302
297
298
268
269
285
235
251
260
262
215
190
189
174
Senior HS Enrollment
161
193
178
218
203
244
229
211
257
284
267
315
318
344
295
303
351
294
288
322
3141
3304
3449
3656
3787
3910
3987
4048
4112
4111
4109
4115
4041
3949
3880
3868
3773
3580
3484
3374
Total Enrollment
Green indicates “Peak”
Red indicates “Trough”

7. 7
Not a New Problem for BOE
• Enrollment cyclicality impacted our district in the 1980s
Source: 1983-1984 Lewisboro Town Planning notes
• As the average Baby Boomer exited the school system in
the early 1970s, enrollment dropped substantially

8. 8
Projecting Cyclical Enrollment
• With a 45 year history of having a very small population of
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20-30 year olds, Lewisboro’s unique demographic has led
to cyclical Kindergarten enrollment
Using our district’s birth rate to project future enrollment in
our district has a very large error rate
The Kindergarten projection one year out, from Dr. Grip’s
2012 study to the actual 2013 data, was off by 10%
A 10% error rate in one year’s time is unacceptable, and
implies error rates as large as 60% over five years’ time
More analysis and thought is required to try to accurately
estimate future Kindergarten enrollment
The current demographic data strongly suggests a new
cycle is just starting

9. 9
KLSD Historical Enrollment

10. 10
Statistical Forecasting LLC Projection
In this scenario, Kindergarten enrollment is projected by multiplying the
average births from 2009-2011 by 1.25.
The most recent 5-year average Cohort-Survival Ratio is used.

11. 11
Projection Assuming Cyclicality
In this scenario, Kindergarten enrollment is assumed to be cyclical, as
it has been between 1960 and 2013.
A 20-year average Cohort-Survival Ratio is used.

12. 12
Projection Assuming Cyclicality during Net Student Inflow
In this scenario, Kindergarten enrollment is assumed to be cyclical, as
it has been between 1960 and 2013.
A 5-year average Cohort-Survival Ratio is used from a period of net
positive student migration (1995-1996 through 1999-2000)

13. 13
Final Thoughts
• Over the past 50 years, Elementary School enrollment has been cyclical
• The normal or “average” Elementary enrollment number is around 1,600
• “Peak” Elementary enrollment is around 2,000 students
• “Trough” Elementary enrollment is around 1,200 students
• What is the district’s plan for handling the next “peak” enrollment cycle?
• How should the district manage periods of trough enrollment?
• Historically, the cycle has lasted roughly 20-30 years. Given the last
Kindergarten class “Peaked” in the late 90s, we should expect another
peak in 5-10 years’ time
• If the next 10 years are going to be different from the 50-year cyclical
history, why is this time different?