Lette to the Editor

Hispanic Subgroups and Intraracial Comparisons In their article on substance use among Mexican-American youth, Chavez and Swaim' argue that "there are important differences in the drug use of subgroups of Hispanics and that there are substantial gaps in our knowledge of both the epidemiology and etiology of Hispanic substance use. The current study addresses one of the important gaps by presenting normative data on substance use among 8th- and 12th-grade MexicanAmerican youth. Mexican-American (MA) youth are compared with White non-Hispanic (WnH) youth residing in the same communities." The use of race or ethnicity as an independent variable in public health research, where Chavez and Swaim's study fits this criterion, deserves some remarks. Given Chavez and Swaim's suggestion that "there are important differences in the drug use of subgroups of Hispanics," these differences should have received priority in their investigation. Until one has an adequate understanding of how these subgroups differ from each other, comparing drug use in MexicanAmerican youth with that in non-Hispanic youth is conceptually inefficient. For example, in the case in which no difference is found between Cuban-American and non-Hispanic youth, can one interchange Cuban-American youth with non-Hispanic youth when comparing them to Mexican-American youth? In Chavez and Swaim's study, any conclusions drawn concerning the epidemiology and etiology of Hispanics are limited to Mexican-American youth. In allowing an effective interpretation of between-group differences, a conceptually efficient model depends upon knowledge of within-group differences. A related issue is the growing interest in investigating intraracial or intraethnic differences in public health. A casual review of the literature reveals that betweenvs within-group differences are often poorly conceptualizd. For example, Rogler, Cortes, and Malgady2 conducted a qualitative, narrative review on the relationship between acculturation and mental-health status among Hispanics. Of the 30 published studies reviewed, over 50%o compared Hispanics to Whites or African Americans. If the goal is to examine the relationship between acculturation and mental-health status among Hispanics, the appropriate comparison is between the various Hispanic subgroups (within-group December 1992, Vol. 82, No. 12

differences) and not between Hispanics and Whites or African Americans (between-group comparison). Being Hispanic is neither a "necessary" nor a "sufficient" cause for acculturation. By definition, being White means no acculturation is possible, and the only time when comparison of Hispanics to African Americans is appropriate is when one assumes that the acculturation process is relatively similar for both groups-a leap of faith. O Frank Y. Wong, PhD Dean R. McKay, A4 The authors are with the Department of Psychology, Hofstra University, Hempstead, NY. Requests for reprints should be sent to Frank Y. Wong, PhD, Department of Psychology, Hofstra University, 1000 Fulton Ave, Hempstead, NY 11550.

References 1. Chavez EL, Swaim RC. An epidemiological comparison of Mexican-American and White non-Hispanic 8th- and 12th-grade students' substance use. Am JPublic Health. 1992;82:445-447. 2. Rogler LH, Cortes DE, Malgady RG. Acculturation and mental health status among Hispanics: convergence and new directions for research. Am PsychoL 1991;46:585-597.

Handedness, Accidents, and Mental State It has been reported that, in contrast with control subjects, ambidextrous sub-

jects ("mixed-handers") are significantly more prone to accidents.1 Excesses of mixed-handers have also been noted in nonclinical samples of persons with schizotypal personality2-3 and in samples of male alcoholics.4 One may wonder whether mental state, rather than handedness per se, is a more immediate cause of the excess accidents involving mixedhanders. [l Wilam H. James, PhD Requests for reprints should be sent to William H. James, PhD, Medical Research Council Mammalian Development Unit, Wolfson House, University College London, 4 Stephenson Way, London, England NW1 2HE.

References 1. Daniel WF, Yeo RA. Handedness and ac-

cidentproneness.AmJPublicHealth. 1991;

81:1346. Letter. 2. Chapman JP, Chapman IJ. Handedness of hypothetically psychosis-prone subjects. J Abnorm PsychoL 1987;96:89-93.

3. Kim D, Raine A, Triphon N, Green ME. Mixed handedness and features of schizotypal personality in a nonclinical sample. J Ne,v Ment Dis. 1992;180:133-135. 4. Nasrallahi HA, Keelor K, McCalley-Whit-

ters M. Laterality shift in alcoholic males. Biol PsychoL 1983;18:1065-1067.

Daniel and Yeo Respond With respect to our finding' that ambidextrous subjects ("mixed-handers") are more susceptible to accidents requiring medical attention than are right- or lefthanded subjects, Dr. James puts forth an interesting and viable hypothesis that deserves further investigation: "mental state" (or, by extrapolation, personality variables2) may be a more "immediate" (i.e., proximate) cause ofthis different rate of accidents than mixed-handedness per se. However, there are four reasons why this hypothesis should be viewed with caution at present. First, only one study1.3 to date has shown that mixed-handers suffer more accidents than do right- or lefthanders. Second, this study was conducted on university students, a sample that may not be representative of the population at large. Third, we reported4 that both left-handers and mixed-handers had significantly higher rates of head injuries than right-handers (mean number of head injuries: 0.51, 0.49, 0.38, respectively, n = 1558; QNM5 = 6.4; df = 1; P < .02; gender-adjusted relative risk = 1.37, 95% confidence interval = 1.07, 1.75) but that there was no difference between mixedand left-handers (QMH = 0.28; df = 1; P > .59). Fourth, it is uncertain whether present-day measures of mental state or personality accurately reflect psychological status immediately prior to the accident and whether mental state thus represents a risk factor for sustaining the accident. Replication studies are badly needed in which personality, neurological, and environmental3,6 variables are concurrently examined with respect to handedness and accident history. Such studies might lend support to specific causal models for the differing accident rates among handedness groups. ] Walter F. Dani MS RonaldA. Yeo, PhD Requests for reprints should be sent to Walter F. Daniel, MS, Department of Psychology, Logan Hall, University of New Mexico, Albuquerque, NM 87131-1161.

References 1. Daniel WF, Yeo RA. Handedness and ac-

cidentproneness.AmJPublicHealth. 1991; 81:1346. Letter. 2. Zuckerman M. Sensation seeking: a comparative approach to a human trait. Behav Brain Sci. 1984;7:413-471.

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