Seminole County, Florida –Population and Housing

Demand Projections

By: Andrew Pagano

October 25th,2015

Figure 1: Seminole County, Florida

Introduction:

Seminole County is located in the central part of the state of Florida, covering a total of 345 square

miles, 309 square miles of which is land, and 36 square miles of water. Seminole County is located

approximately 3.5 miles from Orlando city limits and is known best for having a mostly suburban

characteristics with the exception of some growing communities such as Altamonte Springs and Sanford,

currently in a phase of construction luxury condos along their waterfronts. Sanford is the largest city in

the county with a population of 53,570, according to the U.S. Census. The next largest city in the county

is Apopka, containing a population of 45,587, followed by Altamonte Springs with 42,150. Much of the

development in the county is

actually located on the southern

end, bordering the county Orlando

is located in (Orange County) with

cities like Winter Springs,

Casselberry, Altamonte and

Oviedo. Much of the county is

accessed via state roads or

Interstate 4, however, in the last

two years there has been a

opening of a commuter rail system

known as Sunrail that has serviced

areas from Sanford through Lake

Mary, Longwood, Altamonte

Springs and through Orlando to the

southern tip of the metropolitan

area. Seminole county also has a

history of being a more

conservative community than it’s

more liberal neighboring county of

Orange. Over the last 10 years,

municipalities within Seminole

county have seen tremendous

growth and with that has come an

uptick in number of businesses.

Industries providing employment,

include Professional, scientific,

management, administrative and

waste management services, encompassing 36.9% of the workforce, Educational, health and social

services encompass 14.5%, and Finance, insurance, real estate and rental and leasing encompass 10.6%.

(city-data). There is no doubt Seminole county has experienced significant growth in the last few

decades and in the next section will be discussing the particularities of the population growths along

with housing trends.

Observed Population trends:

The history of this county is founded on exponential growth from the tourism industry existing less than

10 miles away. Ever since the introduction of Disney World, Universal Studios and SeaWorld, the area

has served as a hotspot for those seeking out jobs in the hospitality and service industry. This combined

with its major draw to retired seniors naturally beckoned the kind of growth seen only in the most

rapidly developing countries. The I4 corridor has notorious for two primary things, the first being its

mind-numbing congestion during rush hour and the second, its reputation for having dozens of

construction cranes every mile on the side of the corridor. Central Florida has certainly been no stranger

to growth, as can be seen in figure 1, with barely over 22,000 people in 1940, doubling in 1960 and

surging over 300% in population in 1980. This trend continued and even surpassed over the next 30

years.

The population has been as follows below:

1940 - 22,304

1950 - 26,883

1960 - 54,947

1970 -83,692

1980 - 179,752

1990 -287,529

2000 -365,196

2010 - 422,718

422718

365196

287529

179752

8369254947

2688322304

-100000

0

100000

200000

300000

400000

500000

1930 1940 1950 1960 1970 1980 1990 2000 2010 2020

Po

pu

lati

on

Year

Figure 2: Population by DecadeSeminole County, Florida

Age-Sex Pyramids and Population Trends

1990 Population (Figure 3):

As can be observed from figure 2, the population in Seminole county has two main bulging cohorts at

both the 35-39 year cohorts and the 40-44 year cohorts. Considering the largest bulge around the 35-39

year range, this statistic seems to line up logically due to the county’s median age of 38 years old- 2

years younger than the State median of 40 years old. Naturally, there was a significant population in the

youngest categories of the 5to9 year cohorts and 10-14 year cohorts due to the baby boomer and

generation x procreation period. Additionally, we can once again see the initial population surge of male

births as compared to female births, but ironically a steady tapering off of the survival of males starting

in the 55-59 range and perpetually decreasing the size of male population. This statistic is especially true

of a Floridian county since it is so saturated with retirees of all walks of life, some of which settled in the

state as a permanent fixture till the end of their lifespan.

15000 10000 5000 0 5000 10000 15000

0-4

5 to 9

10 to 14

15-19

20-24

25-29

30-34

35-39

40-44

45-49

50-54

55-59

60-64

65-69

70-74

75-79

80-84

85+

Figure 3: AGE-SEX PYRAMID 1990

Male

Female

2000 Population (Figure 4):

2000 population in Seminole county remains largely middle-aged population during this period. Much of

the result of migration in the county is that middle-aged and some elderly populations are being

replaced at significant rates as other populations get older or move out. It can be deduced that during

this census, much of the over 77,000 population increase happened in cohorts 5-9, 10-14, 30-34, 35-39

and 50-54. 2000 was a transformative year for this county, as much of the Northeast, Midwest and some

other southern states came in droves to give the warm weather, tourism and hospitality industry a try.

Population Projections:

During this exercise, several models of population increase were used to understand how accurate or

inaccurate they would predict the population for 2010 using data from growth in the past. Of these 7

models, 4 made under-shot predictions, 1 model overshot by over 90,000 and 2 models simply did not

work. Linear projection ended up projecting a population of 385,011 with an r-square of .90, under-

predicted by 37,707. Exponential model did not work once I attempted to add decimal places to the

equation and subsequently predicted not change in population. Logarithmic predicted a population of

382,879 with an r-square of .933, Polynomial was optimistic in its prediction, stating a population of

513,387 with a supposed r-square of .98. Power model also did not manage to extrapolate any

20000 15000 10000 5000 0 5000 10000 15000 20000

0-4

5 to 9

10 to 14

15-19

20-24

25-29

30-34

35-39

40-44

45-49

50-54

55-59

60-64

65-69

70-74

75-79

80-84

85+

Population

Age

Figure 4: AGE-SEX PYRAMID 2000

Male

Female

meaningful prediction form the prior population numbers. Moving average was one of the most

inaccurate, predicting a population of 326,363 and modified exponential predicted a population of

356,484 with an r-square of .83. Below is a table with all the results from the models and the different

methodologies used to come to these conclusions.

Comparing parameter estimates Seminole County, FL Table1:

Model Equation R2 MAPE Actual 2010

Predicted 2010

2010 APE

Linear y=ax+b 0.903454 59.6% 422,718

385,011 0.089202

Exponential y=a*ebx 0.970589 100.0% 422,718

422,718 0.010000

Logarithmic y=a+b*ln(x) 0.933087 67.0% 422,718

382,879 0.094250

Polynomial y=ax2+bx+c 0.980398 22.0% 422,718

513,387 0.002150

Power y=a*xb 0.971516 100.0% 422,718

422,718 1.000000

Moving average yt=avg(yt-1,yt-

2,yt-3,…) 35.0% 422,718

326,363 0.227943

Modified exponential y=c-a*(b^x) 0.8335 121.0%

422,718

356,484 1.210000

2010 Age Cohort Projections:

After following through with the process of using bottom-up age-sex cohorts to project

population in 2010, I found this to be a bit flawed in its results. The age cohort variations for the

projection were not in line with the actual 2010 census data. Additionally, the cohort

component under-predicted the population for the county to 346,448, an estimate off by over

77,000. The specific problem with the projection and its relation to the census data is that it

predicted a bulge in population cohorts between the 40-44 ranges, whereas the actual census

demonstrates a higher propensity towards the 50-54 year cohorts. The projection also over-

predicts the cohort for 10-14 range and remains over-predictive of the age groups up to 30-34,

where it under predicts for that specific cohort. The cohort migration residual baed on the

difference between the each projection and the observed data ended up being a large factor for

change in the model from the years 1990 through 2010. Considering the under-predictive

nature of these models and projections, there was frequently much difference between the

actual population and the projected population, thus resulting in high migration residual. All

things considered, the accuracy of this migration residual may have some caveats, but overall

seems to logically explain some of the far-of predictions these projections have due to the

impressive growth patterns the county has continued to experience over the last 30 years, with

not even a model to keep up with the level of growth experience in this county.

20000 10000 0 10000 20000

0-4

10-14

20-24

30-34

40-44

50-54

60-64

70-74

80-84

Population

Age

Figure 5: PROJECTION AGE-SEX PYRAMID 2010

MAle

Female

20000 10000 0 10000 20000

0-4

10 to 14

20-24

30-34

40-44

50-54

60-64

70-74

80-84

Population

Age

Figure 6: CENSUS AGE-SEX PYRAMID 2010

Male

Female

Housing demand:

Housing in Seminole County is a hot button topic for a range of reasons, from economic to

political. Relying on 2000 and 2010 data, Seminole county has experienced a robust number of

housing constructions over the last few decades. It is evident that natural disasters have played

a more significant role in housing units lost during hurricanes in Florida because of the more

frequent and intense nature of hurricanes in this region of the county, but for the sake of this

report, I have chosen to keep the number to a conservative 5% loss. Further than that, the other

main factor that has affected the housing market in Florida is the economy. During one of the

peak years for new housing construction, namely 2003, the number of new building permits was

around 3,348, to juxtapose this after 6 years and a massive financial crisis, including the housing

loan bubble, that number dropped sharply after 2007 and sat at its lowest level of growth in

2009 , which was 840, a difference of almost 40% between 2009 to 2003 numbers. Over the

next 5 years and encompassing projections from years earlier than 2010 it is estimated that the

county will have a 66,294 unmet housing demand and should be accounted for when policy-

makers and developers come to the table in coming years.

Housing Demand

j. Change in the Number of Households 2000-2020 48,857

k. Change in the Number of Vacant Units 2000-2020 17,264

l. Units that Must be Replaced 2000-2020 2,787

m. Units Lost to Disaster 2000-2020 1,500

n. Units Lost to Conversion 2000-2020 750

o. Units Lost to Demolition 2000-2020 537

p. Total Number of Units Needed 2000-2020 68,908

q. Projected Housing Completions 2001-2020 2,614

r. Unmet Housing Demand 2011-2020 66,294

Conclusion:

In conclusion, Seminole county has seemingly turned out to be so promising in growth over the

years that it manage to surpass even the most sophisticated models except for the Polynomial

model. Migration has proven to be a huge factor in the population change over the last 3

decades, as well as elderly mortality. Housing demand over the last 15 years has been strong,

but highly volatile and directly affected by the bigger picture problems that transpired in our

economy during the housing bubble and financial crisis. Hopefully, the county has learned some

lessons at both the policy-making level and the development level to have more accountability

and prudent practices when addressing the furture of housing demand s to avoid large-scale

vacancies and minimize the effects of foreclosures in these communities. The future for

Seminole county is even brighter than the sunniest day in summertime, promising to not only

continue its growth, but capitalize on the prospect of economic development that has evolved

over time in the area and provide equitable, affordable housing, transportation and services for

all citizens of this county.

References:

http://www.city-data.com/county/Seminole_County-FL.html

www.census.gov

https://www.census.gov/history/www/programs/demographic/decennial_census.html

http://www.seminolecountyfl.gov/