URP 5261: Forecasting for Plan Development

Glossary of Terms


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- A -

At Risk
A term used in demographics to identify that portion of the population that could experience a given condition at a given time. This term is most applicable in the Cohort-Component Model. For example, females aged 10-49 are "at risk" to give birth to children in a given five year period. In contrast, all people are "at risk" of mortality in any given five year period.

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- B -

Base Multiplier

1. The ratio of the total employment in year t to the basic sector employment in that year.
2. The employment multiplier that estimates local basic sector employment impacts and allows analysts to project non-basic sector job creation given an increase in basic sector employment.

 

Base Period

The interval between the base year and the launch year

 

 

Base Year

The year of the earliest data used in the projection

 

 

Basic Sector (or Local Sector)

That part of the local economy that consists of firms and parts of firms whose economic activity is dependent on factors external to the local economy.

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Cohort
Portions of a given population identified by their age and sex (and sometimes racial) characteristics. The male cohort aged 0-4 refers to those males in a given population aged 0-4.99 at a given time. The population is broken into these groups in the Cohort-Component Model so that the different components of population change (births, deaths, migration) can be applied more precisely to an area's population.

Component
The three means of change to a given population; Births, Deaths, and Migration. Because the components of population change are experienced differently by males and females, at different ages, and by different racial groups, the Cohort-Component Model applies the rates of change for these components to the different age/sex (and race) cohorts.

Contingency Forecast
A statement of a possible future, including the highest and lowest plausible levels of population.

 

County Business Patterns
An important source of local employment data. Included are the number of firms, employees, and measures of outputs for firms by
SIC code.

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Economic Base
1. A theory for understanding the local economy that breaks that economy into a
basic and a non-basic sector.
2. An analytical technique that divides the local economy into basic and non-basic sectors and then calculates a
base multiplier to determine the impact of the "engine" (the basic sector) of the local economy.

Estimate
A calculation of a current or past value of a variable typically based on symptomatic indicators of change in that variable.

 An analyst cannot "estimate" future conditions.

Exponential Curve
An

Export
A product or service that is sold outside of the local economic area by a local firm.

EPPROC
The acronym for the Electronic Planning Professional Council web site project.

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Fertility Rate

The likelihood that a given "at risk" population (females aged 10-49) will give birth in a given period of time. These rates, estimated by the US Census Bureau, are provided only for age-specific groups 10-14, 15-19, 20-24, 25-29, 30-34, 34-39, 40-44, 44-49.

 

Firm
A company that employs any number of employees. A business, company, or corporation.

 

Forecast
The projection selected as the one most likely to provide an accurate prediction of the future value of a variable. This is a judgmental statement about what the analyst believes to be the most likely future.



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Geometric curve
An

Gompertz curve
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- I -

Import
A product or service that is brought into and sold in the local economic area by a non-local firm.

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- L -

Launch Year
The year of the most recent data used in the projection

 

Linear Curve
An

Location Quotient
A calculated ratio between the local economy and the economy of some reference unit that. This ratio is calculated for all industries to determine whether or not the local economy has a greater share of that industry than expected. If an industry has a greater share than expected of a given industry, then that "extra" industry employment is assumed to be Basic because those jobs are above what a local economy should have to serve local needs.

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- M -

Migration
The movement of people (or firms) into or out of a given geographic area. Clearly, migration can take on two forms: 1) in-migration: the movement of persons (or firms) into a given geographic area, and 2) out-migration: the movement of persons (or firms) out of a given geographic area.

Mortality Rate
A rate calculated for a given geographic area that presents the likelihood that a person will experience mortality ("die") in a given period of time. These rates are usually calculated for five year age/sex/race cohorts and applied in the Cohort-Component Model. A related concept is that of the
Survival Rate.

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- N -

Non-basic sector (or non-local sector)
That part of the local economy that consists of firms and parts of firms whose economic activity is dependent on local economic conditions.

 

Normative Forecast
Statement about the desired future. An attainable future whose definition has evolved from the planning process.

 

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- P -

Parabolic Curve
An

Projection
The numerical outcome of a particular set of assumptions regarding future values of a variable

. A conditional "if, then" statement about future conditions. Projections cannot be incorrect if the calculations are performed correctly.

Projection Horizon(s)
The interval(s) between the launch year and the target year(s)

 

Projection Interval
The increment in which projections are made

 

 

Pure Forecast
The “most likely” future given unanticipated public or private initiatives. This is a predicted future based upon the continuation of existing trends and expected initiatives.

 
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- S -

Shift-Share Technique
A modification to the constant-share projection formula that introduces a shift term to the formula. This technique attempts to account for differences between a given industry's local growth rate and the reference region's growth rate that results in the shift of that industry's employment into or out of a region. Past share of a given industry is no longer assumed to be constant.

 

Shift Term
The key difference between the Shift-Share technique and the Constant Share technique. This term is calculated by subtracting the Regional Growth Rate for a given industry over a given period of time from the Local Growth rate for a given industry over a given period of time: {Local GR Industry I - Regional GR Industry I}.

 

Standard Industrial Classification (SIC)
A classification system that organize industries in an increasing level of detail ranging from general economic sectors (i.e. manufacturing, services) to specific industry segments (i.e. commercial sports, laundry businesses). This system organizes industries by their output. However, SIC Codes have recently been bypassed by the
North American Industry Classification System (NAICS) that resulted from North American Free Trade Agreement.

Survival Rate
A rate calculated for a given geographic area that presents the likelihood that a person will survive in a given period of time. These rates are usually calculated for five year Age/Sex/Race cohorts and applied in the Cohort-Component Model. For example, white males aged 10-14 might have a five year survival rate of .99240, which means that 99.24% of the males are expected to survive the next five year period. The US Census Bureau calculates this statistic at the state level for all states.

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Target Year(s)
The year(s) for which the variable is projected

 

 

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Revised: January 2003