Appendix: Methods

Sample and Data Collection

The 102 occupations included in this sample were identified by first downloading a list of licensed occupations from, a career website sponsored by the United States Department of Labor. That list was then cross tabulated against occupational lists maintained by the BLS. Any occupation that did not appear in the BLS lists was excluded, thus creating a list of “recognized” occupations. Finally, the BLS-referenced list was rank ordered by average income. All occupations that fell above the national average income were excluded, resulting in a final list of low- and middle-income occupations.

Specific licensure requirements were collected from the following sources:

  • State statutes and administrative codes
  • State licensing boards
  • State agencies (i.e., department of education, department of public safety, department of human services, etc.)
  • Professional associations
  • Direct correspondence with a licensing authority

All requirements were recorded for each occupation. To derive the requirements that would be part of the analyses, we chose those that were the most consistent across the occupations. Therefore, some requirements, such as surety bonds, character references or CPR training, were collected but not included in the analyses.

After gathering the occupational requirements, we also eliminated a few occupations that were originally included in the sample. A review of the requirements revealed that those entering a given occupation were limited only by age or grade level minimums and were not required to register with the state in any way, as one would have to do in a traditional licensure procedure. For example, many states require that amusement ride attendants have to be at least 16, but those individuals do not have to prove their ages to a state agency or receive permission from the state to work. For that reason, we classified these occupations as unlicensed and eliminated them from the sample.

Likewise, within certain occupations there were some states that required only age or grade level minimums. In those cases, the states were not counted as licensing those occupations. However, in a few instances, states had no minimum requirements—such as fees, age or training—but required workers to register with the state. In such cases, the states were counted as licensed.

It is also worth noting that determining the exact requirements needed for a license, or even whether a particular activity is licensed, is not always clear cut. State statutes and regulations are often confusing or ambiguous and sometimes change. As we learn of clarifications, corrections and updates, we will update our data accordingly and post new information at

Measuring Burden

To derive a measure of burden across occupations and states, we combined the five licensure requirements—fees, education/experience, exams, minimum grade level and minimum age—in a multi-step process.


Step 1: Each requirement’s sub-requirements were combined. Three of the requirement types—fees, education/experience and exam—had sub-requirements 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. Note that only fees associated with the initial license were included, which means continuing education fees, renewal fees and the like are not included. The final metric was dollars.

Likewise, discrete exams were summed across exam types, which commonly included written and practical exams. The final metric was number of exams.

Combining education/experience sub-requirements itself required a multi-step process. Some of the education/experience sub-requirements are reported in days, some in hours, some in years, some in degree completion and so forth. Therefore, we converted the sub-requirements into a common measurement of days.

  • Hours were converted to days in training by first dividing hour requirements by six, which would be about how much time someone might spend in full-time training per day. This was converted to weeks by dividing by five, which represents 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 someone is shut out of her/his chosen occupation as a result of education/experience requirements.
  • Years were multiplied by 365.
  • Degrees were converted to years, which were then multiplied by 365. Although completion times of degree programs vary, we chose standard completion times of: Associates=2 years, Bachelor’s=4 years, Master’s=2 years.

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

Note that not all states had minimums in all requirements. For example, a fire alarm installer’s license in Montana requires fees, an exam and a minimum age, but no education/experience. Oregon, however, requires fees, education/experience and an exam, but no age minimum. Thus, in any state with a license but no minimums in a given requirement, a zero value was assigned to the requirement. In states with no license, the cells in the spreadsheets were empty.

Step 2: Requirements were averaged across states.

Step 3: Because the different requirement types are measured in different units—dollars, years, days, grades, etc.—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 z-scores.

Step 4: Recognizing that some requirements are more burdensome than others, we applied weights to the requirements. This acknowledges that education/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/experience requirement and 1.5 to the grade-level requirement.

Step 5: The weighted z-scores for each requirement were summed. This score was used for ranking in Table 3 above.

Step 6: The weighted z-scores were multiplied times the number of states that license. This score was used for the ranking in Table 4 above.


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, grade level, and age requirement for each state.

Step 2: Requirements were converted into z-scores.

Step 3: Requirements were weighted as described above.

Step 4: The weighted z-scores for each requirement were summed. This score was used for the ranking in Table 7 above.

Step 5: The weighted z-scores were multiplied times the number of licensed occupations. This score was used for the ranking in Table 8 above.