Appendix A: General Methods

Sample Collection and Third 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. 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.

The second edition of License to Work, released in 2017, made several major revisions to the original list of occupations to achieve greater clarity and consistency in licenses observed across states. 1  By coincidence, both editions record licensing burdens for 102 occupations, though the mix of occupations changed slightly. These revisions significantly impede comparisons between the first and second editions.

Revisions for the third edition were much more minor, meaning this third edition of License to Work can be compared with the second. Revisions fell into two categories. First, for the third edition, we observed SAT and ACT exams and their fees when those exams were the least expensive option for licensure. These revisions are confined to two public school occupations, preschool teacher and head coach for high school sports, for which some states accept SAT or ACT exam scores for licensure.

Second, the third edition corrected clear errors, some of which related to minor inconsistencies in methodology. We corrected both types of errors and report when we revised data from the first or second edition in the comparison dataset.

Creation of Comparison Dataset

This report provides a comparison dataset of occupations with licenses consistently observed across the first (2012), second (2017) and third (2022) editions of License to Work. Because of the significant methodological differences between the first and second editions described above, the comparison dataset covers only 45 occupations from the first edition. However, for both the second and third editions, it covers all 102 occupations.

We created the comparison dataset by combining data for the second edition with data for the third edition for all 102 occupations. We also included data for the 45 occupations we consistently observed since the first edition and identify which occupations are consistently observed across all three editions. Where we revised data from the first or second edition, we identify these corrections with a data flag and description. In addition, we include a new feature for the third edition, occupation groups, which are consistently recorded across all three editions.

Data Collection

We collected the data for this report over a period of two years—February 2020 to March 2022—and closed data collection on March 18, 2022, to allow time to prepare this report for publication. We did so occupation by occupation. This means occupations researched earlier on in the data collection process may have outdated data, as licensing requirements can change over time. However, we made every effort to ensure that our data are current at the close of data collection.

During data collection for this report, we followed several principles to determine which regulations to count 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 traditional licenses requiring personal credentials as well as simple registrations requiring only notification of name and address and payment of a fee—so long as these registrations are required to practice.

Second, we count state-mandated permission slips as licenses even if states call them something else, such as “permits,” “certifications” or, indeed, registrations. For example, South Carolina issues a mandatory certificate for athletic trainers. Although it is not called a license, we count it as a license because it is necessary to legally practice as an athletic trainer in South Carolina and thus functions as a license. 2  For simplicity, throughout this report, we refer to all state-mandated permission slips as licenses, regardless of what states call them.

Third, because this report is concerned with state requirements to practice an occupation, it does not include laws that restrict only the use of an occupational title (e.g., “interior designer,” “registered interior designer” or “certified interior designer”), even when such laws are called “licenses.” This is because these “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.

Several other principles guided our selection of which license or licenses to record in cases where more than one license 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 occupations. However, for occupations in which sole proprietorship is not a realistic option, this report records licenses for workers. For example, dietetic technicians assist in the provision of nutrition programs under the supervision of dietitians and thus, by definition, cannot be sole proprietors.

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

Third, where a state offers multiple paths to licensure in an occupation, this report generally records the least burdensome one to avoid overstating burdens. However, in some cases, we record a more restrictive license in keeping with an occupation’s definition or in the interest of properly stating the burdens for continuous practice of an occupation. For 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.

Fourth, we only considered certain types of fees in determining which path to licensure to observe. We recorded fees that were easily quantifiable and mandated by the state, whether or not they were paid directly to the state. For example, we recorded fees that are paid directly to the licensing board—such as a license, application, recovery fund or background check fee. We also recorded fees for a business license when it was required by the licensing board. And we recorded exam fees charged by third parties—such as Praxis—if the state required all applicants to take that exam. In effect, the third-party, which may be a private company, is acting under the authority granted to it by the state. This also means third-party fees charged for certifications—such as NCIDQ interior designer certification—were recorded. 3

However, we did not record the fees associated with educational requirements such as bachelor’s degrees—tuition, administrative, and other school-related fees. Although such fees may be high, these are not set by the licensing board nor are they easily quantifiable given the variety of degree types and differing speeds at which applicants may finish their education. Because we did not consider the cost of education when deciding which licensure path to choose, we underestimate the true burdens imposed on license applicants—in terms of fees and costs—when observing educational requirements.

Fifth, similar to fees, we only considered exams that were easily quantifiable and mandated by the licensing authority when weighing different paths to licensure. This included common types of exams given by licensing boards and third parties—such as written, verbal and practical exams—as well as less common ones—such as on-the-job evaluations and field inspections. We also recorded exams required during courses—whether the courses and exams are administered by the licensing board or not—if they were specifically required for licensure.

However, educational requirements with exams not specifically required for licensure—such as the number of exams one has to take to get a college degree—were not recorded. As a result, we underestimated the number of exams one would have to take when considering such routes to licensure. 

Sixth, we did not record competency-based training requirements for licensure when a state also had quantifiable requirements aspirants could complete instead. For example, Oregon’s beauty licenses allow for both competency-based training programs and ones denominated in hours. 4  In this instance and others like it, we recorded the route denominated in hours as this route was quantifiable and thus more easily recorded in our data. However, some states have only competency-based training requirements for certain licenses. For example, in the milk sampler occupation, some states require on-the-job training and specify how long it should take, while other states require similar training but do not specify length. In such cases, when possible, we estimated the length of training based on the length of similar training of defined length. When we had no indication of the length of a training requirement, we altogether omitted that requirement from our data; typically, such cases were unique to one state.

Following these principles, we recorded the main requirements to secure a license across five categories for all 102 occupations across all 50 states and the District of Columbia. The five categories are fees, education and experience, exams, minimum age, and minimum grade. We also report whether the occupation is licensed in the state, as well as the eight cases we identified where a state prohibits the practice of an occupation without a higher-level license (described in Appendix B). We made note of other state requirements—such as surety bonds, character references and CPR training—during the data collection process but excluded them from the data since they were not common to all occupations we observed.

Occasionally, states allow aspirants to choose from a list of options to fulfill certain licensing requirements. In those cases, this report observes the option that would result in 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. 5  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 and experience, we observe the cosmetology school route.

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

  • 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.
  • Third-party education and exam providers’ websites.
  • CareerOneStop.
  • Direct correspondence with licensing authorities.

Measuring Burden

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


Step 1: We combined each requirement’s subrequirements for each license. Three of the requirement types (fees, exams, and education and experience) often had subrequirements that needed combining. For fees, aspirants must often pay fees of various types: application fees, processing fees, licensing fees and so forth. We summed these to create an overall fee. The final metric was dollars. Likewise, we summed discrete exams across exam types, which commonly included written, oral and practical exams. Some states also require multi-part exams, which we treated as one exam. The final metric was number of exams. 

Combining education and experience subrequirements itself required a multi-step process. Some of the education and experience subrequirements are reported in days, some in hours, some in years, some in degree completion and so forth. We therefore converted these subrequirements to a common measurement of days, representing an estimate of calendar days lost while meeting education and experience requirements. In the final data, we rounded total days lost to zero significant digits when at or above one day, but one significant digit when below one day to avoid this information rounding down to zero. The conversions are as follows:

  • We converted education and experience clock or contact hours 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, we converted it to weeks by dividing by five, to represent a five-day work week. We then converted weeks back to days by multiplying by seven.
  • We converted apprenticeship clock or contact hours to days by first dividing hour requirements by eight, which is about how much time a person might spend per day in an apprenticeship. We converted this to weeks by dividing by five, to represent a five-day work week. We then converted weeks back to days by multiplying by seven. 
  • We divided days at or over five by five, to represent a five-day work week. We then multiplied the result by seven to convert it to estimated calendar days lost.
  • We multiplied weeks by seven.
  • We multiplied months by 30.33.
  • We multiplied years by 365.
  • Contractor occupations: We multiplied the number of required jobs for licensure by 16, which is the approximate average number of days a contracting project takes. 6  We converted this to weeks by dividing by five, to represent a five-day work week. We then converted weeks to estimated calendar days lost by multiplying by seven.
  • Mobile home installer: We multiplied the number of required jobs for licensure by 30.33 because, on average, a mobile home installation project takes about a month. 7  
  • Direct entry midwife: We multiplied the required number of births for licensure by 20, which is the average number of days a midwife will go between attending births. 8
  • We divided continuing education units by seven, which is the number of units that can be completed in one day. 9
  • We multiplied credit/semester hours by seven, which assumes that one credit hour can be completed in a seven-day week.
  • We converted degrees to years, which we then multiplied by 365. Although completion times of degree programs vary, this report uses standard completion times (i.e., associate = 2 years, bachelor’s = 4 years, master’s = 2 years).

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

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

Step 2: We averaged requirements across states.

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

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

Step 5: We summed the weighted T-scores for each requirement. We used this score for the ranking in Table 4.

Step 6: We multiplied each occupation’s weighted T-score by the number of states that license the occupation. We used this score for the ranking in Table 5.


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

Step 2: We converted requirements to T-scores.

Step 3: We weighted requirements as described in Occupations–Step 4 above.

Step 4: We summed the weighted T-scores for each requirement. We used this score for the ranking in Table 6.

Step 5: We multiplied each state’s weighted T-score by the number of occupations the state licenses. We used this score for the ranking in Table 7.