Sampling Error
An error arising from the fact that it is not statistically possible, short of a 100 percent sample, to select a sample which corresponds perfectly to the population from which it is selected. As the size of a sample increases, the magnitude of the sampling error decreases. Sampling errors differ from other kinds of statistical errors in that they occur at random and are unbiased. Non-sampling errors, on the other hand, are errors that can be attributed to mistakes in data collection, tabulation, analysis, etc.

Seasonal Adjustments
Sometimes monthly data is adjusted to minimize the changes in any time series which result from normal annual occurrences such as holiday shopping seasons, summer vacation, and weather patterns. National and state LAUS estimates, for example, are made for both seasonally adjusted and not seasonally adjusted.

Seasonal Industry
An industry in which activity is affected by regularly recurring weather changes, holidays, vacations, etc. The construction industry is typically characterized as seasonal.

Self-Employed Workers
Persons who work for profit or fees in their own business, profession, trade, or farm. Only the unincorporated self-employed are included in the self-employed category in the class of worker typology. Self-employed persons who respond that their businesses are incorporated are included among wage and salary workers, because technically, they are paid employees of a corporation.

Series Break
A large change in the level of a time series resulting from: (1) a major change in methodology; (2) a major change in industry definition; (3) a major industry or area coding error; (4) the permanent loss of a major reporter; or (5) area redefinition. If a series has been broken, data prior to the break are not comparable to data after the break.

Service Delivery Area (SDA)
A geographical area, designated by the governor, within which employment and training services are provided under the Job Training Partnership Act. Designated as Local Workforce Investment Areas according to the provisions of the Workforce Investment Act of 1998. New Hampshire is a single SDA state; there are no designated sub-state areas.

Standard Industrial Classification (SIC)
A structure in which all establishments are assigned a four-digit code according to their primary economic activity. SIC codes are published by the Federal Office of Management and Budget in the Standard Industrial Classification Manual. The SIC taxonomy is being phased out and replaced with the six-digit North American Industrial Classification System (NAICS) taxonomy.

Standard Occupational Classification (SOC)
A standard classification for occupations used in social and economic statistical reporting programs, including private, public, and military occupations.

Survey Week
The week that includes the twelfth of the month is used as a reference period for most labor force data.