NBCE Publications

Practice Analysis of Chiropractic 2020

Executive Summary                                       Download (PDF)

Practice Analysis of Chiropractic 2020     Download (PDF)

If you are interested in earlier versions of the practice analysis report (from 2015, 2010, 2005, 2000, or 1993), please visit the Practice Analysis Archive page.

The Practice Analysis of Chiropractic 2020 contains a project report, survey analysis, and summary of chiropractic practice in the United States. Published by the National Board of Chiropractic Examiners, the report summarizes responses from chiropractic practitioners in all 50 states, the District of Columbia, Puerto Rico, the U.S. Virgin Islands, and other U.S. territories.

The Analysis provides legislators, insurance companies, educators, and the general public with an overview of the chiropractic field and its effectiveness as a healthcare profession. Over the years, these updated summaries of the chiropractic profession help determine the content of NBCE’s licensure exams. In 2020, for the first time, the practice analysis contains information about the graduates of chiropractic programs who do not practice chiropractic and those who practice part time.

Doctors of Chiropractic were invited to take the survey online with all graduates of chiropractic programs encouraged to provide input. Survey respondents reported information on their daily tasks and professional responsibilities. The survey included questions about the types of conditions chiropractors see in their practices and the frequency and management of those conditions.

This is the sixth survey of U.S. chiropractors, which is conducted by the NBCE approximately every five years. Surveys were conducted in 1991, 1998, 2003, 2009, 2014, and 2019; with the resulting reports published in 1993, 2000, 2005, 2010, 2015, and 2020 respectively.

Response of Chiropractic Organizations to the COVID-19 Pandemic: A Descriptive Report

The Journal of Manipulative and Physiological Therapeutics – Published: June 13, 2020

Authors: Claire D. Johnson, DC, MSEd, PhD; Craig S. Little, DC, EdD; Tamara A. Sterling, MBA; Scott Gojkovich, BA; Karlos Boghosian, DC; Michael A. Ciolfi, DC, DBA

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The coronavirus disease-2019 (COVID-19) pandemic has strained all levels of healthcare and it is not known how chiropractic practitioners have responded to this crisis. The purpose of this report is to describe responses by a sample of chiropractors during the early stages of the COVID-19 pandemic.


We used a qualitative-constructivist design to understand chiropractic practice during the COVID-19 pandemic, as described by the participants. A sample of chiropractic practitioners (doctors of chiropractic, chiropractors) from various international locations were invited to participate. Each described the public health response to COVID-19 in their location and the actions that they took in their chiropractic practices from April 20 through May 4, 2020. A summary report was created from their responses and common themes were identified.


Eighteen chiropractic practitioners representing 17 locations and 11 countries participated. A variety of practice environments were represented in this sample, including, solo practice, mobile practice, private hospital, US Veterans Administration health care, worksite health center, and group practice. They reported that they recognized and abided by changing governmental regulations. They observed their patients experience increased stress and mental health concerns resulting from the pandemic. They adopted innovative strategies, such as telehealth, to do outreach, communicate with, and provide care for patients. They abided by national and World Health Organization recommendations and they adopted creative strategies to maintain connectivity with patients through a people-centered, integrated, and collaborative approach.


Although the chiropractors in this sample practiced in different cities and countries, their compliance with local regulations, concern for staff and patient safety, and people-centered responses were consistent. This sample covers all 7 World Federation of Chiropractic regions (ie, African, Asian, Eastern Mediterranean, European, Latin American, North American, and Pacific) and provides insights into measures taken by chiropractors during the early stages of the COVID-19 pandemic. This information may assist the chiropractic profession as it prepares for different scenarios as new evidence about this disease evolves.
Key Indexing Terms: Health Occupations; Chiropractic; COVID-19; Pandemics
The Evolution of the NBCE

Dynamic Chiropractic – March 1, 2020, Vol. 38, Issue 0

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The Evolution of the NBCE

By Max Russell


Despite women making up nearly half of the U.S. labor force,1 female representation across nationwide boardrooms has yet to reflect that. According to the data governance company Equilar Inc.,2 women hold 20.2 percent of board seats for companies in the Russell 3,000 index (representing about 98 percent of all publicly traded U.S. companies). While this is a milestone that achieves the goal set by the national advocacy group 2020 Women On Boards3 to have women exceed 20 percent of corporate board positions by 2020, the work for representation still continues.

In order to better reflect the makeup of a company’s employees, as well as the customers they serve, there has been a push for more women in the boardroom. The state of California responded by passing the first law that requires all public companies headquartered in the state to have at least one female board member by the end of 2019, with that number increasing by the close of 2021 depending on the size of the board.4 Another approach calls for investment firms to promote the cause of gender diversity by showing less financial interest in companies without women on their board of directors.5

While legal and financial incentives help push the issue, they also face pushback from those claiming the new law forces businesses to hire on the basis of gender.6 The debate is bound to continue, but for companies looking to broaden the perspective of their leadership team, the experiences of female board members extend well beyond gender.

NBCE Board of Directors: Three New Faces Reflect the Board’s Evolution

NBCE - Copyright – Stock Photo / Register Mark From Left: Kimberly Driggers, JD, Cynthia Tays, DC and Carol Winkler, DC. The soon-to-be-released 2020 Practice Analysis of Chiropractic7 discovered that for chiropractors under 30 years old, the number of female practitioners is 53.2 percent, surpassing what was once a dominantly male profession. However, as reported earlier by Dynamic Chiropractic,8 “It was not that long ago that women didn’t hold any director positions with the National Board of Chiropractic Examiners (NBCE).”

In an effort to evolve, the NBCE began to fill this gap on its board of directors. The Federation of Chiropractic Licensing Boards appointed its vice president, Dr. Carol J. Winkler, as FCLB representative on the NBCE Board of Directors. Dr. Winkler has been following the changes in the industry from a young age while sitting in on countless breakfast room conversations between her family. Her father and uncle were involved in creating the laws and statues that advanced the chiropractic profession by creating acceptance and a seat at the collective health care table within the United States and internationally. Dr. Winkler has watched the industry change dramatically with an intimate understanding of the work needed to advance the chiropractic field.

Dr. Winkler’s father, Dr. Carroll H. Winkler, served on the National Board of Chiropractic Examiners from 1991 to 1995, making her the first second-generation member of the NBCE Board of Directors.9 Continuing the legacy of education at home, Dr. Winkler is married to a fellow chiropractor and their children have the same front-row seat to the industry she was afforded at their age.

Another valued perspective comes from doctors of chiropractic who are the first in their families such as Dr. Cynthia Tays,10 who was elected to the NBCE Board of Directors by delegates of district IV. Dr. Tays served as a qualified medical evaluator in the state of California, as well as a designated doctor in the state of Texas. Both positions required her to determine if treatments performed on patients improved their quality of life.

Through her experience in workers’ compensation, she noticed an issue regarding chiropractors continuing to perform the same treatment on patients, regardless of the outcome. This perpetuated a cycle of chiropractic visits that did not benefit patients.

Inspired by her drive to remove abuses from the industry, Dr. Tays served as president of the Texas Board of Chiropractic Examiners before serving as the district IV director and board chair for the Federation of Chiropractic Licensing Boards. As a board member of the NBCE, she continues to advocate for the advancement of education and scientific scrutiny for the benefit of patients.

In terms of breaking new ground, there is no better example than Kimberly Driggers, JD, the first non-chiropractor on the NBCE Board of Directors. Ms. Driggers brings her experience as an attorney and lobbyist to boardroom discussions with the added perspective of drafting and defending bills and amendments that fight for the equality of chiropractic.

While serving as the assistant general counsel to the Florida Chiropractic Association, Ms. Driggers fought against the insurance industry’s practice of denying chiropractic the same telehealth insurance coverage offered to other medical professions.11 Although an in-person visit with a doctor provides the most comprehensive medical consultation, telehealth allows patients to seek advice regarding nutrition, range of motion, or other check-ups that can be handled outside of a doctor’s office.

The analytical, writing and contract-drafting skillset of a lawyer representing the chiropractic profession brings a valued legal perspective to the national testing agency.

Necessary Changes for the Future

When companies select their next board member, there is a wide pool of qualified professionals with varied perspectives to choose from. To direct a company to a sustainable future, it is important to have leadership insights from more than just men. The three women on the 11-member NBCE Board of Directors bring lifelong education, scrutiny and legal perspectives to guide the future of the profession.

According to Dr. Daniel M. Côté, president of the NBCE, “Dr. Winkler, Dr. Tays, and Ms. Driggers have made a significant impact since coming on the Board. We value their knowledge, input, and perspective, and could not be happier as we prepare to showcase the benefits of chiropractic care to the next generation.”


  1. Labor Force Participation Rate of Women, 1950 to 2015 and Projected to 2024. U.S. Bureau of Labor Statistics, 1 July 2017.
  2. Stych A. “Women’s Representation on Boards Reaches a Milestone.” Biz Women, 12 Sept. 2019.
  3. Berkhemer-Credaire B. “2020 Women on Board.” 2020 Women on Board, 30 June 2019.
  4. Wamsley L. “California Becomes 1st State to Require Women on Corporate Boards.” NPR, 1 Oct. 2018.
  5. Brown C. “How Wall Street is Pushing for More Women.” Axios, 18 Nov. 2019.
  6. Pender K. “Lawsuit Challenges California’s Women-on-Boards Law.” San Francisco Chronicle, 13 Nov. 2019.
  7. Himelfarb I, Hyland J, Ouzts Jr. N. Practice Analysis of Chiropractic 2020. National Board of Chiropractic Examiners.
  8. Petersen DM. “Can the National Board Evolve?” Dynamic Chiropractic, 1 May 2019.
  9. “NBCE Mourns the Passing of Dr. Carroll H. Winkler.” National Board of Chiropractic Examiners, 15 Apr. 2019.
  10. “Dr. Cynthia Tays Elected to NBCE Board.” National Board of Chiropractic Examiners, 24 Sept. 2018.
  11. “Kimberly Driggers.” Speaker bio for FCA’s The National, 2019.

 Max Russell is the public-relations coordinator for the National Board of Chiropractic Examiners (NBCE).

The Transition to Digital Presentation of the Diagnostic Imaging Domain of the Part IV Examination of the National Board of Chiropractic Examiners

The Journal of Chiropractic Education – Published: January 2020

Authors: Igor Himelfarb, PhD; Margaret A. Seron, DC; John K. Hyland, DC, MPH; Andrew R. Gow, DC; Nai-En Tang, PhD; Meghan Dukes, DC, MSPT; Margaret Smith, and Michele Fisher

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This article introduces changes made to the diagnostic imaging (DIM) domain of the Part IV of the National Board of Chiropractic Examiners examination and evaluates the effects of these changes in terms of item functioning and examinee performance.


To evaluate item function, classical test theory and item response theory (IRT) methods were employed. Classical statistics were used for the assessment of item difficulty and the relation to the total test score. Item difficulties along with item discrimination were calculated using IRT. We also studied the decision accuracy of the redesigned DIM domain.


The diagnostic item analysis revealed similarity in item function across test forms and across administrations. The IRT models found a reasonable fit to the data. The averages of the IRT parameters were similar across test forms and across administrations. The classification of test takers into ability (theta) categories was consistent across groups (both norming and all examinees), across all test forms, and across administrations.


This research signifies a first step in the evaluation of the transition to digital DIM high-stakes assessments. We hope that this study will spur further research into evaluations of the ability to interpret radiographic images. In addition, we hope that the results prove to be useful for chiropractic faculty, chiropractic students, and the users of Part IV scores.

Keywords: Chiropractic, Educational Measurement, Diagnostic Imaging, Psychometrics
Current State and Future Directions of the National Board of Chiropractic Examiners

The Journal of Chiropractic Education – Published: January 2020

Authors: Norman E. Ouzts, Jr, DC; Igor Himelfarb, PhD; Bruce L. Shotts, DC, MS; and Andrew R. Gow, DC

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The objective of this paper is to describe changes made to chiropractic national board examinations in the United States, including methodologies in test scoring, and to discuss future directions in test development and administration being considered by the National Board of Chiropractic Examiners (NBCE). Additionally, this paper serves as an introduction to the articles written by the NBCE staff and published in this issue of the journal. Statistical perspective on the properties of a test are presented, and reasons for the NBCE moving to item response theory for test scoring are described. NBCE consideration of on-demand testing and changes implemented in the Part IV practical examination are also discussed.

Keywords: Chiropractic, Educational Measurement, Education, Certification/Standards
Article A Two-Level Alternating Direction Model for Polytomous Items With Local Dependence

Education and Psychological Management – Published: September 2019

Authors: Igor Himelfarb, PhD; Katerina Marcoulides, PhD; Guoliang Fang, ABDMath; & Bruce Shotts, DC, MS.

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The chiropractic clinical competency examination uses groups of items that are integrated by a common case vignette. The nature of the vignette items violates the assumption of local independence for items nested within a vignette. This study examines via simulation a new algorithmic approach for addressing the local independence violation problem using a two-level alternating directions testlet model. Parameter values for item difficulty, discrimination, test-taker ability, and test-taker secondary abilities associated with a particular testlet are generated and parameter recovery through Markov Chain Monte Carlo Bayesian methods and generalized maximum likelihood estimation methods are compared. To aid with the complex computational efforts, the novel so-called TensorFlow platform is used. Both estimation methods provided satisfactory parameter recovery, although the Bayesian methods were found to be somewhat superior in recovering item discrimination parameters. The practical significance of the results are discussed in relation to obtaining accurate estimates of item, test, ability parameters, and measurement reliability information.


Keywords: testlet response theory (TRT), violation of local independence, Bayesian methods, Markov Chain Monte Carlo (MCMC), generalized maximum likelihood estimation (GMLE)
Variables Associated with Successful Performance on the National Board of Chiropractic Examiners Part IV Examination

The Journal of Chiropractic Education – Published: July 2019

Authors: Igor Himelfarb, PhD; Bruce Shotts, DC, MS, John K. Hyland, DC, MPH; Andrew R. Gow, DC

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Objective: The objectives of this study were to (1) identify factors predictive of performance on the National Board of Chiropractic Examiners Part IV exam and (2) investigate correlations between the scores obtained in the Part I, Part II, Physiotherapy, and Part III exams and the Part IV examination.

Methods: A random sample of 1341 records was drawn from National Board of Chiropractic Examiners data to investigate the relationships between the scores obtained on the National Board of Chiropractic Examiners exams. A hierarchical multiple regression analysis related the performance on Part IV to examinee’s gender, Part IV repeater status, and scores obtained on the Part I, Part II, Physiotherapy, and Part III exams.

Results: The analyses revealed statistical relations among all National Board of Chiropractic Examiners exams. The correlations between Part IV and Part I ranged from r = .31 to r = .4; between Part IV and Part II from r = .34 to r = .45. The correlation between Part IV and Physiotherapy was r = .44; between Part IV and Part III was r = .46. The strongest predictors of the Part IV score were found to be examinees’ scores in Diagnostic Imaging, β̂ = .19, p < .001; Chiropractic Practice, β̂ = .17, p < .001; Physiotherapy, β̂ = .15, p < .001; and the Part III exam β̂ = .19, p < .001.

Conclusions: Performance on the National Board of Chiropractic Examiners Part IV examination is related to the performance in all other National Board of Chiropractic Examiners exams.


Keywords: Chiropractic; Clinical Competency; Educational Measurement; Regression Analysis.

Score Production and Quantitative Methods Used by the National Board of Chiropractic Examiners for Post Exam Analyses

The Journal of Chiropractic Education – Published: July 2019

Authors: Igor Himelfarb, PhD; Bruce Shotts, DC, MS; Nai-En Tang PhD; & Margaret Smith

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The National Board of Chiropractic Examiners (NBCE) uses a robust system for data analysis. The aim of this work is to introduce the reader to the process of score production and the quantitative methods used by the psychometrician and data analysts of the NBCE.


The NBCE employs data validation, diagnostic analyses, and item response theory–based modeling of responses to estimate test takers’ abilities and item-related parameters. For this article, the authors generated 1303 synthetic item responses to 20 multiple-choice items with 4 response options to each item. These data were used to illustrate and explain the processes of data validation, diagnostic item analysis, and item calibration based on item response theory.


The diagnostic item analysis is presented for items 1 and 5 of the data set. The 3-parameter logistic item response theory model was used for calibration. Numerical and graphical results are presented and discussed.


Demands for data-driven decision making and evidence-based effectiveness create a need for objective measures to be used in educational program reviews and evaluations. Standardized test scores are often included in that array of objective measures. With this article, we offer transparency of score production used for NBCE testing.

Keywords: Chiropractic, Education, Psychometrics, Scoring Methods, Statistical Data Analysis


A Primer on Standardized Testing: History, Measurement, Classical Test Theory, Item Response Theory, and Equating

The Journal of Chiropractic Education – Published: June 2019

Author: Igor Himelfarb, PhD

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Objective: This article presents health science educators and researchers with an overview of standardized testing in educational measurement. The history, theoretical frameworks of classical test theory, item response theory (IRT), and the most common IRT models used in modern testing are presented.

Methods: A narrative overview of the history, theoretical concepts, test theory, and IRT is provided to familiarize the reader with these concepts of modern testing. Examples of data analyses using different models are shown using 2 simulated data sets. One set consisted of a sample of 2000 item responses to 40 multiple-choice, dichotomously scored items. This set was used to fit 1-parameter logistic (PL) model, 2PL, and 3PL IRT models. Another data set was a sample of 1500 item responses to 10 polytomously scored items. The second data set was used to fit a graded response model.

Results: Model-based item parameter estimates for 1PL, 2PL, 3PL, and graded response are presented, evaluated, and explained.

Conclusion: This study provides health science educators and education researchers with an introduction to educational measurement. The history of standardized testing, the frameworks of classical test theory and IRT, and the logic of scaling and equating are presented. This introductory article will aid readers in understanding these concepts.


Keywords: Chiropractic; Education; Educational Measurement.



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