Appendix A: General Methods

Sample Collection and Second Edition Revisions

The 102 occupations sampled in the first edition of License to Work, released in 2012, were identified by first downloading a list of licensed occupations from CareerOneStop (, a career website sponsored by the U.S. Department of Labor. That list was then cross tabulated against occupational lists maintained by the Bureau of Labor Statistics (BLS). Any occupation that did not appear in the BLS lists was excluded to create a list of “recognized” occupations. Finally, the BLS-referenced list was rank ordered by average income. Any occupation that fell above the national average income was excluded, resulting in the list of 102 low- and middle-income occupations observed for the original License to Work report.

For this second edition of License to Work, several revisions were made to the original list of occupations to achieve greater clarity and consistency in licenses observed across states. By coincidence, both editions record licensing burdens for 102 occupations, though the mix of occupations changed slightly. These revisions limit the comparability between editions.

First and most expansive, the second edition takes an improved approach to recording contractor licenses. While both editions of License to Work cover contracting work in both commercial and residential settings, the first edition includes contractor licenses that are not specific to a particular setting, sometimes called a “general contractor license,” only in commercial contractor occupations, labeling those occupations “General/Commercial.” Even though such general licenses often apply to residential contracting work, the first edition excluded them from residential contractor occupations to avoid double counting. By contrast, the second edition records such licenses in both commercial and residential contractor occupations. While this results in counting some licenses twice, it gives a more robust and accurate description of the residential contracting landscape. The contractor occupations are now labeled “Commercial” and “Residential.” See Appendix B for further details on contractor licensing.

Second, several occupations from the first edition have been split into two separate occupations for this new edition. This was done to more fully capture the scope of work within the occupations. The occupations affected are:

  • Three contractor occupations: door repair contractor, landscape contractor and paving equipment operator contractor, each of which has been separated into commercial and residential in the second edition.
  • Truck driver, which has been separated into “Tractor-Trailer” and “Other.” The first edition looked at licenses for smaller large-capacity trucks, such as box trucks used for furniture delivery (now labeled “Other”), but excluded licenses for larger trucks, such as semis and other tractor-trailers (now labeled “Tractor-Trailer”).
  • Animal control officer, which has been separated into “Animal Control Officer” and “Wildlife Control Operator” to better capture two closely related fields. Animal control officers generally work for the government and handle neglected or abused animals, while wildlife control operators work in the private sector and deal with nuisance wild animals.
  • HVAC contractor, which has been separated into “HVAC Contractor” and “HVAC Sheet Metal Contractor” to better capture two closely related fields. When recording HVAC contractor licenses, the first edition focused on licenses to install sheet metal attached to an HVAC system, such as ducts. This occupation is now labeled HVAC sheet metal contractor, and HVAC contractor has been added to capture licenses to install HVAC systems. Both occupations have commercial and residential categories.

Third, within the broad category of child care workers, different licenses may apply depending on the setting and other factors, making it difficult to record burdens consistently. In the interest of consistency and in keeping with a preference for recording sole-proprietor licenses (see the “Data Collection section” below), this second edition observes licenses required to run a day care facility out of one’s home (“Child Care Family Home”).

Fourth and finally, the second edition eliminates several occupations from the original sample:

  • Five tester or inspector occupations: backflow prevention assembly tester, cathodic protection tester, cross-connection survey inspector, fire sprinkler system tester and tank tester. Regulations governing testers and inspectors vary widely across states, making it unusually difficult to achieve consistency in license observation. As a result, these occupations have been eliminated from the second edition.
  • Court clerk. Court clerks work in courts of law. However, the first edition observed municipal clerk licenses, which are required to work in city or town councils, not courts of law. Since no state issues a license to work as a court clerk, the occupation has been eliminated from this second edition.
  • Non-contractor pipelayer. The first edition recorded licenses required for those who work for pipelayer contractors. The second edition observes instead licenses required to work as a sole proprietor in the field (“Pipelayer Contractor”).

Data Collection

During data collection for this report, several principles were used to determine which regulations should be counted as occupational licenses. First, this report counts as a license any state (not federal or municipal) permission slip required to legally work in an occupation. This includes licenses that require personal credentials and simple registrations that require only notification of name and address and payment of a fee to the state, as long as such registration is mandatory.

Second, licenses are included even if states call them something else, such as a “permit” or “certification.” For example, South Carolina issues a certificate for athletic trainers. Although it is not called a license, it is included in this report because it is necessary to legally practice as an athletic trainer in South Carolina and thus functions as a license. For simplicity, throughout this report, any state-mandated permission slip is referred to as a license.

Third, because this report is concerned with state requirements to practice an occupation, it does not include laws that only restrict the use of an occupational title (e.g., “interior designer,” “registered interior designer” or “certified interior designer”), even where such laws are called “licenses.” This is because such “titling” laws (which may take the form of certification schemes) do not restrict freedom of occupational practice.

Fourth, this report excludes laws that set standards for an occupation but do not explicitly require government permission to practice it. For example, some states require only that bartenders be of a minimum age or that they be trained by their employers. This report does not consider such states as licensing bartenders.

In addition to these principles, several others guided the selection of which license or licenses to record in cases where more than one could apply to a given occupation. First, when possible, this report records licenses for sole proprietors in order to show the burdens entrepreneurs face when trying to enter an occupation. However, for occupations in which sole proprietorship is not a realistic option, this report records licenses for workers. For example, dietetic technicians—one of the occupations observed in this report—assist in the provision of nutrition programs under the supervision of dietitians and thus, by definition, cannot work on their own as a sole proprietor.

Second, in cases where multiple licenses are required to practice an occupation, this report records the requirements for all of those licenses. This approach more completely captures the requirements associated with earning a license to practice fully and independently. For example, because most states require aspiring barbers to obtain an apprentice’s license before obtaining a full barber’s license, this report records both licenses.

Third, where a state issues multiple licenses for the practice of an occupation, this report generally records the least restrictive one to avoid overstating burdens. However, in some cases, a more restrictive license is recorded in keeping with an occupation’s definition or in the interest of properly stating the burdens for continuous practice of an occupation. For example, in Utah, mason contractors can choose between two license classifications: general masonry or stone masonry. While the general masonry classification requires one more exam than the stone masonry classification, it better fits the mason contractor occupation’s definition. The general masonry classification is therefore observed in this report, even though it is more burdensome. In another example, many states issue both a continuously renewable professional teaching license for public preschool teachers and a preliminary one. Licenses of the latter type are less burdensome, but they are also only temporary. For this reason, this report observes states’ continuously renewable licenses.

Following these principles, the main requirements to secure a license were recorded across five categories for all 102 occupations across all 50 states and the District of Columbia: fees, education/experience, exams, minimum age and minimum grade. Other common state requirements, such as surety bonds, character references and CPR training, were noted during the data collection process but excluded from the data. Tuition for required third-party schooling was excluded as well, as it is an indirect cost that is often variable and impractical to record.

In those occasional cases where a state allows occupational aspirants to choose from a list of options to meet certain licensure requirements, this report observes the option that would reflect the lowest burden in the data. For example, to obtain a cosmetology license in Michigan, aspirants must complete either 1,500 hours of cosmetology school or a two-year apprenticeship. Under this report’s conversion metrics (see the “Measuring Burden” section below), the cosmetology school route results in an estimated 350 days lost, while the apprenticeship route results in 730 days lost. Because it results in fewer days lost to education/experience, the cosmetology school route is used in the data.

For this second edition of License to Work, all licenses and requirements were researched from scratch. To collect licensure requirements, the following resources were consulted:

  • State statutes and administrative codes.
  • State licensing board websites.
  • State agency websites (e.g., departments of education, departments of public safety, departments of human services).
  • Professional association websites.
  • CareerOneStop.
  • Direct correspondence with licensing authorities.

Measuring Burden

To derive a measure of burden across occupations and states, the five licensure requirements collected were combined in a multi-step process.


Step 1: Each requirement’s subrequirements were combined. Three of the requirement types (fees, education/experience and exams) had subrequirements that needed combining. For fees, applicants are often required to pay fees of various types: application fees, processing fees, licensing fees, etc. These were summed to create an overall fee. The final metric was dollars. Likewise, discrete exams were summed across exam types, which commonly included written, oral and practical exams. Some states also require multi-part exams, which were considered as one exam. The final metric was number of exams.

Combining education/experience subrequirements itself required a multi-step process. Some of the education/experience subrequirements are reported in days, some in hours, some in years, some in degree completion and so forth. These subrequirements were therefore converted into a common measurement of days, representing an estimate of calendar days lost while meeting licensing requirements. The conversions are as follows:

  • Education/experience clock or contact hours were converted to days by first dividing hour requirements by six, which is about how much time a person might spend per day in full-time education (such as trade school or courses) or gaining on-the-job experience (such as working as a technician for an employer). If the total number of hours was equal to or more than 30, this was converted to weeks by dividing by five, to represent a five-day work week. Weeks were then converted back to days by multiplying by seven. The final number represents the total number of calendar days a person is shut out of their chosen occupation as a result of education/experience requirements.
  • Apprenticeship clock or contact hours were converted to days by first dividing hour requirements by eight, which is about how much time a person might spend per day in an apprenticeship. This was converted to weeks by dividing by five, to represent a five-day work week. Weeks were then converted back to days by multiplying by seven. The final number represents the total number of calendar days a person is shut out of their chosen occupation as a result of apprenticeship requirements.
  • Days at or over five were divided by five, to represent a five-day work week, then multiplied by seven to convert them into estimated calendar days lost.
  • Weeks were multiplied by seven.
  • Months were multiplied by 30.33.
  • Years were multiplied by 365.
  • Jobs (contractor occupations) were multiplied by 16, which is the approximate average number of days a contracting project takes.1 This was converted to weeks by dividing by five, to represent a five-day work week. Weeks were then converted into estimated calendar days lost by multiplying by seven.
  • Jobs (mobile home installer occupation) were multiplied by 30.33, because, on average, a mobile home installation project takes about a month’s time.2
  • Births (direct entry midwife occupation) were multiplied by 20, which is the average number of days a midwife will go between attending births.3
  • Continuing education units were divided by seven, which is the number of units that can be completed in one day.4
  • Credit/semester hours were multiplied by seven, which assumes that one credit hour can be completed in a seven-day week.
  • Degrees were converted to years, which were then multiplied by 365. Although completion times of degree programs vary, this report uses standard completion times (i.e., associate’s=2 years, bachelor’s=4 years, master’s=2 years).

For minimum grade level, the final metric was a number representing the minimum grade (i.e., 10th grade=10, high school completion=12, etc.). For minimum age, it was years.

Not every license comes with every type of requirement. For example, a school bus driver’s license in Illinois requires fees, exams and a minimum age, but no education/experience or minimum grade. In such cases, a zero value was assigned to absent requirements. For states with no license for a given occupation, no value was assigned.

Step 2: Requirements were averaged across states.

Step 3: Because the different requirement types are measured in different units—dollars, days, exams, grades and ages—they could not simply be added or averaged to produce a single measure of burden for each occupation. Instead, requirements were converted into a common metric—known as standard scores—to facilitate combining. Specifically, requirements were converted into T-scores.

Step 4: Because some requirements are more burdensome than others, weights were applied to the requirements. This approach acknowledges that education/experience, for example, represents more of a barrier to entering an occupation than fees or age requirements. Specifically, a weight of 20 was applied to the education/experience requirement, while a weight of 1.5 was applied to the minimum grade requirement.

Step 5: The weighted T-scores for each requirement were summed. This score was used for the ranking in Table 2.

Step 6: Each occupation’s weighted T-score was multiplied by the number of states that license the occupation. This score was used for the ranking in Table 3.


Step 1: The final requirement metrics created in Occupations–Step 1 above were averaged across all occupations for each state. This resulted in an average fee, education/experience, exam, minimum grade and minimum age requirement for each state.

Step 2: Requirements were converted into T-scores.

Step 3: Requirements were weighted as described in Occupations–Step 4 above.

Step 4: The weighted T-scores for each requirement were summed. This score was used for the ranking in Table 5.

Step 5: Each state’s weighted T-scores were multiplied by the number of occupations licensed by the state. This score was used for the ranking in Table 6.

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