Vol. 52, No. 4, Summer 1992 195

Guest Editorial: It’s Not the Numbers that Matter, It’s What You Do with Them

Robert J. Weyant, DMD, DrPH Department of Public Health and Community Dentistry School of Dental Medicine University of Pittsburgh Pittsburgh, PA 15261

The title of this editorial is taken from the punch line of a short story. The story centers around a women’s defense of her husband, a statistician, against charges that he is engaged in the most utterly boring of profes- sions, a charge with which many a dental student would likely agree (more on that later). I would suggest that the phrase also applies to what appears to be a sea change occurring within the pages of this journal. I t is true that science has always relied heavily on numbers to answer questions and to convey information, and this has cer- tainly been true of contributors to the Journal of Public Health Dentistry, both present and past. What has been changing, however, is what these contributors have been doing with the numbers.

While reading the most recent issue of the IPHD, I was struck by the sophistication of the statistical language used in several articles. This prompted me to investigate just how much things have changed in recent times with regard to the overall statistical sophistication of JPHD articles. To this end, I mounted a strictly nonscientific perusal of a nonrandom sample of IPHD offerings over the last ten years. What I discovered, not too surprisingly, was an unmistakable trend that confirmed my suspi- cions.

With several exceptions, all of the articles from the 1983 issues possess as their most sophisticated statistical con- cept a frequency distribution that was occasionally ac- companied by a standard error. Articles by Hunt (l), Isman (2), and Marcus et al. (3) went on to introduce measures of association between variables with either chi-square or least-squares regression. Descriptive statis- tics, however, were the rule.

Jumping forward to 1989 we begin to find a predomi- nance of analytical articles that use techniques such as: the analysis of variance and the analysis of covariance (41, Fisher’s exact test (5), Cronbach’s alpha (6), and more multiple regression, but now with transformed variables (7).

Looking at the current year (1992), one can find the following phrase, ” . . . factors with eigenvalues greater than 1.0 were retained and items with factor loadings greater than .SO following varimax rotation were in- cluded in the factor” (8). Elsewhere, Gary Koch, a world-

renowned statistician, and Jim Beck develop, in a dental context, a number of statistical methods, including pro- portional hazards models and cumulative logistic mod- els (9).

Unmistakably, what we have been doing to the num- bers has changed over the last ten years. To my way of thinking, this increased statistical sophistication is a wel- come but problematic change. One way to think of it is that in 1983 the statistical methods of virtually every article in the JPHD could readily be understood by any- one with a first course in statistics, as is commonly re- quired during the master‘s degree in public health. By 1992, many of the methods presented required at least a second course in statisticsand oftena much more special- ized understanding of subjects such as factor analysis and the analysis of covariance. In one sense, it is not crucial that a reader understand all of the statistical de- tails of a study to be able to understand the findings of the research; however, an understanding of the methods section is essential if one wishes to assess critically an article’s worth or make generalizations from a study to other situations.

With the notableexceptionof theJournal offheAmerican Dental Association, this trend toward statistical sophisti- cation is generally true for many leading dental journals. In fact, the reversion of JADA to a magazine format typifies the alternative we face. When professionals lack the training to understand the literature in their field, one of three things will likely happen: they will stop reading; they will continue to read, but will be unable to evaluate critically what they read; or they will demand that the literature be watered down to what I call ”research lite.” The consequence of this behavior is that professionals will not have the tools necessary to acquire new knowl- edge, perhaps the single most important skill for a health professional. As a result, they will be locked into an understanding of clinical practice acquired during their years of training; or worse, they will approach the litera- ture uncritically, thereby embracing too quickly marginal techniques and unproven products.

When the practitioners of a profession have neither a scientific basis for their clinical practice, nor a rational method of acquiring new knowledge, then that profes-

196 Journal of Public Health Dentistry

sion can rightly be called a "trade." If dentistry is to be successful in providing appropriate care and in compet- ing for the ever-declining pool of health care and research dollars, then it must ensure that its members are per- ceived as scientifically based health care professionals. Dr. Alvin Morris was correct when over ten years ago he said: "A profession, the existence of which is justified by service to the public, can maintain control of its destiny only if it is capable of providing the leadership for how it will change. The status quo will not be maintained" (10).

We should ask ourselves just what level of understand- ing is required for most readers of the contemporary dental literature. In particular, what capabilities should a graduate dentist possess if he or she is to be an informed and discerning consumer of dental research. If, as I sus- pect, improvement in clinical practice is the main reason most dentists read the literature, then a greater under- standing of research methods is necessary than is pres- ently attainable during a typical undergraduate dental education. For the minority of dentists who go to spe- cialty training and master's degrees in an academic envi- ronment, there is some hope that they will be exposed to adequate levels of statistical and epidemiologic concepts; however, most dentists do not seek such training.

By addressing these comments to the readers of the JPHD, I am preaching to the choir. But the remedy to this dilemma must come from those of us who work in de- partments of dental public health or community den- tistry within dental schools. Without trying to sound brazen or self-serving, it is the "public healthers" who are often the only faculty trained in understanding the "methods" section of most of the clinical and epidemio- logic dental literature. Therefore, it falls to us to begin to remake the curriculum in a way that will prepare future professionals, at a minimum, to be able to understand the research literature. Unfortunately, it is these very future professionals, constrained by their present limited vision of what their future professional lives will require, who will object most strenuously to the addition of such "ut- terly boring and irrelevant courses" as statistics and epi- demiology. Dental students, quite naturally, are more

concerned with acquiring clinical skills than with learn- ing how to think scientifically. It becomes our job to convince them that the skills and knowledge they learn in school will become outdated and that, in the long run, learning how to acquire new knowledge is what is gen- uinely important.

The inclusion of dental public health on the National Boards has provided us with an opportunity. We can now make a case for an adequate amount of time in the predoctoral curriculum to present not only the concepts of dental public health, but also to offer rigorous courses in statistics and epidemiology. In addition, we must en- sure that dental specialty residents receive even greater clinical research training, for they will be the ones who must provide the future scientific basis for clinical prac- tice. It is time to consider how dental public health can provide the leadership to help dentistry make these es- sential changes, for the status quo should not be main- tained.

References 1. Hunt RJ. Community characteristics, opinion leadership, and f lue

ridation outcome in small Iowa communities. J Public Health Dent

2. Isman R. Effects of the dentist as the primary information source about fluoridation. J Public Health Dent 1983;43:27483.

3. Marcus M, Koch AL, Gershen JA. Construction of a population index of adult oral health status derived from dentists' preferences. J Public Health Dent 1983;43:284-94.

4. Rich SK, Friedman JA, Schultz LA. Effects of flossingonplaque and gingivitis in third grade schoolchildren. J Public Health Dent

5. Wolfolk Mw, Wirth Faja B, Bagramian RA. Relation of sources of systemic fluoride to prevalence of dental fluorosis. J Public Health Dent 1989;49:78-82.

6. ter Horst G, Hammann-Konings GMJ, van Hegten MJ, et al. AIDS and rnfection control: Amsterdam dentists surveyed. J Public Health Dent 1989;49:201-5.

7. SaliveME, Corolla JM, Brewer TF. Dental health of maleinmatesin a state prison system. J Public Health Dent 1989;4983-6.

8. Bader JD, Sams DH. Factors assodated with job and career satisfac- tion among dental hygienists. J Public Health Dent 1992;5243-51.

9. Koch GG, Beck JD. Statistical methodologies useful for the analysis of data from risk-assessment studies. J Public Health Dent 1992;52146-67.

10. Advanced dental education: recommendations for the 80's. Issues in Dental Health Policy, Battle Creek, MI: WK Kellogg Foundation, 1980.

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