PREVENTIVE
MEDICINE
20,
414-430 (1991)
Preventing Alcohol, Marijuana, and Cigarette Use among Adolescents: Peer Pressure Resistance Training versus Establishing Conservative Norms’ WILLIAM
B.
HANSEN,
PH.D.,*,*
AND
JOHN
W.
GRAHAM,
PH.D.t
*Department of Public Health Sciences, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27103; and tDepartment of Preventive Medicine, School of Medicine, University of Southern California, Los Angeles, California 9ooo7 Background. Two strategies for preventing the onset of alcohol abuse, and marijuana and cigarette use were tested in junior high schools in Los Angeles and Orange Counties, California. The first strategy taught skills to refuse substance use offers. The second strategy corrected erroneous normative perceptions about prevalence and acceptability of use among peers and established conservative groups norms regarding use. Methods. Four experimental conditions were created by randomly assigning schools to receive (a) neither of the experimental curricula (placebo comparison), (b) resistance skill training alone, (c) normative education alone, or (d) both resistance skill training and normative education. Students were pretested prior to the program and post-tested 1 year following delivery of the program. Results. There were main effects of normative education for summary measures of alcohol (P = O.OOll), marijuana (P = 0.0096), and cigarette smoking (P = 0.0311). All individual dichotomous measures of alcohol, marijuana, and tobacco use indicated significant reductions in onset attributable to normative education. There were no significant main effects of resistance shill training. Conclusion. These results suggest that establishing conservative norms is an effective strategy for preventing substance use. 0 1991 Academic Press, Inc.
INTRODUCTION
Alcohol, tobacco, and marijuana have long been known to be drugs of first use (1, 2). Alcohol and tobacco are known to increase long-term risk of disease and premature mortality (3-5). Alcohol use among youth is a risk factor for morbidity and mortality due to accidents (4). In the nation’s current war on drugs, educational programs frequently target these three substances for primary prevention. Research to date has shown great promise for preventing cigarette use among adolescents (620). Fewer studies that have targeted marijuana use have been conducted (9, 11, 12, 14, 16, 21). Nonetheless, there is evidence that programs that prevent the onset of cigarette use also curtail the onset of marijuana use. To date, alcohol use and misuse among adolescents have not been reliably reduced by prevention programming (9, 13, 16, 22-27) although several recent studies suggest small reductions in alcohol use due to preventive efforts (11, 14, 28, 29). Several recent reviews and research reports have expressed serious doubt that ’ Supported by a grant (ROl-AAO6201) from the National Institute on Alcohol Abuse and Alcoholism. 2 To whom reprint requests should be addressed. 414 0091-7435/91$3.00 Copyright ‘0 1991 by Academic Press, Inc. AU rights of reproduction in any form reserved.
SUBSTANCE
USE PREVENTION
415
school-based alcohol prevention is feasible given the widespread acceptance of the behavior (9, 30, 31). Most substance use prevention programs have utilized eclectic strategies, typically with multiple components that defy precise theoretical interpretation. Programs that have been successful to date have tended to include instruction about the nature of peer pressure and skills to resist peer pressure as one component (32). Indeed, even programs that include a number of intervention techniques often ascribe their successprimarily to the impact of teaching students to resist pressure. Nonetheless, the lack of reliable effects on preventing alcohol use and the continual mixing of multiple strategies leads one to question whether peer pressure resistance training, as the single strategy, can account for preventive effects. Particularly, it is possible that it is the establishment of conservative norms regarding use rather than resistance skills that accounts for lower use among particular subgroups (33). Ironically, peer pressure resistance training programs have been consistently confounded with other programmatic strategies that have the potential to establish conservative norms through the correction of erroneous normative beliefs (34). To date, two distinguishable strategies for addressing the issues of social i&hiences have been developed. The first strategy to be tested involves teaching skills to resist peer pressure to use alcohol and other substances. This strategy was developed in responseto the known statistical relationship between substance use among friends and the onset of use among individuals who associate with friendship groups who use (34). Implied by this relationship, and validated to some extent by an examination of the process of onset (35), is the idea that young people perceive peer pressure to participate in substance use in order to be accepted by the peer group. To counter this pressure, programs teach young people to identify situational pressuresto conform to group behavior and teach skills to refuse offers and demands to use while maintaining group membership. The second strategy involves the correction of erroneous perceptions about the prevalence and acceptability of alcohol use. The roots of this strategy are derived from the propensity of young people to overestimate actual prevalence of all forms of substanceuse (34,364O). This overestimation may lead young people to expect use to be normative when, in fact, it is not. This may create an internally generated expectation that the reference group will find use of substances to be desirable and appropriate. To counter this, programs provide students with feedback about actual rates of use and publicize the conservative attitudes toward substance use that exist in the peer group. The Adolescent Alcohol Prevention Trial is an g-year project the purpose of which is to explore the potential of two strategies for deterring the onset of substanceuse in youth. This study involves replicating longitudinal tests of these two strategies in four separate cohorts of students, two cohorts of students that receive programming during the fifth grade, and two that receive initial programming during the seventh grade. This report concerns only the first cohort of seventh-gradestudents. The primary focus of the study was on preventing alcohol use and misuse among adolescents. Cigarettes and marijuana, the use of which correlates with alcohol consumption (l), were also addressed.
416
HANSEN
AND
GRAHAM
METHODS Subjects and Setting
During the 1987-1988school year, 12junior high schools in Los Angeles and Orange Counties, California, were recruited to participate in the study. Prior to delivery of the program, seventh-gradestudents and parents gave informed consent. Experimental Design
Schools were stratified by size, test scores, and ethnic composition and then randomly assigned to receive one of four intervention programs (41). The first program (Information) consisted of four 45-min lessonsabout the social and health consequencesof using alcohol and other drugs. The second program (Resistance Training) consisted of four lessons about the consequences of using substances plus five lessons that taught students to identify and resist peer and advertising pressure to use alcohol and other substances. The third program (Normative Education) included four information lessons plus five lessons that corrected erroneous perceptions of the prevalence and acceptability of alcohol and drug use among peers and established a conservative normative school climate regarding substance use. The fourth program (Combined) included three lessons about information, three and one-half lessons teaching resistance skills, and three and one-half lessons establishing conservative norms. Components of these programs are described in Table 1. These four programs result in two main effects that may be tested: normative education vs no normative education and resistance training vs no resistance training. Programs were delivered entirely by project staff. Program specialists devoted full time effort to teaching. Each had received a minimum of 2 weeks of intensive training. Several had helped with the initial development of both programs and had several years of experience in delivering these types of programs prior to their participation in this study. Previous analyses of the quality of implementation indicate high fidelity of performance (42). Measures
Students were pretested using a questionnaire that assessedtheir use of alcohol, marijuana, and cigarettes. For each of these substances, subjects were asked to report on cumulative lifetime consumption and use during the 30 days prior to the survey. For alcohol, students also reported the number of times they had previously been drunk and their alcohol consumption during the past 7 days. For alcohol measures,responseswere framed in terms of numbers of drinks. Cigarette responseswere framed in terms of numbers of cigarettes. For example, responses to cumulative lifetime alcohol consumption included (a) none or sips (for religious service), (b) sips (not for religious service), (c) part or all of one drink, (d) 2 to 4, (e) 5 to 10, (f) 11 to 20, (g) 21 to 100, and (h) more than 100. Similar scales were constructed for each alcohol and tobacco item. Marijuana items used dichotomous (yes/no) responses.Subjects also reported whether they had discipline problems at school during the previous year and whether they had engagedin violent
Definition of drugs, alcohol is a dw Film/discussion-The Glug (Churchill Films)
Definition of drugs, alcohol is a drug Positive and negative, shortterm, and social consequences of drinking using Socratic Method Parent interview homework, consequences of drinking Prevention Baseballquestion-answer game about consequences of drinking
Question Box-answers to student-generated questions about alcohol and drugs
1
2
4
3
ICU
Session Definition of drugs, alcohol is a dw Positive and negative, shortterm, and social consequences of drinking using Socratic Method Parent interview homework, consequences of drinking Review of consequences, homework Types of social pressure Techniques to refuse Refusal practice Parent interview about peer pressure Assertiveness Role-played refusals
Definition of drugs, alcohol is a dw Positive and negative, shortterm, and social consequences of drinking using Socratic Method Parent interview homework, consequences of drinking Review of consequences, homework Survey about prevalence of alcohol use among students
Survey results Agree/disagree opinion statements Parent interview homework, appropriate/inappropriate alcohol use Class opinions about alcohol use continuum Class discussion of appropriate/ inappropriate alcohol use Nondrinker interview homework-advice
Pressure refusal practice Film/discussion-The Glug
RT
Norm
Curriculum
TABLE 1 PROGRAMCONTENTOFFOVRCVRRKVLA
Types of social pressure Techniques to refuse Refusal practice Parent interview about peer pressure
Survey results Agree/disagree opinion statements
Definition of drugs, alcohol is a drug Positive and negative, shortterm, and social consequences of drinking using Socratic Method Parent interview homework, consequences of drinking Review of consequences, homework Survey about prevalence of alcohol use among students
Combined
Techniques used by advertisers Evaluating alcohol ads Parent/child homework about alcohol advertising Review of homework Develop anti-alcohol advertisements Question box Videotaped commitments to resist pressure to drink alcohol
Developing positive friendships, including nondrinking as a positive quality Prevention Baseball Alcohol rap songs-informal rules about alcohol Question box Videotaped rap songs and personal opinion statements
6
I
8
9
10
Standing up to pressure-report of personal resistance experiences Prevention Baseball
RT
Review of homework Film/discussion-The Glug
Norm
5
Session
Curriculum
TABLE l-Continued
Assertiveness Role-played refusals Parent interview homework, appropriate/inappropriate alcohol use Class opinions about alcohol use continuum Class discussion of appropriate/ inappropriate alcohol use Nondrinker interview homework--advice Techniques used by advertisers Evaluating alcohol ads Parent/child homework about alcohol advertising Alcohol rap songs-informal rules about alcohol Question box Standing up to pressure-report of personal resistance experiences Videotaped rap songs, personal opinion statements and commitments to resist pressure to drink
Combined
SUBSTANCE USE PREVENTION
419
or destructive behavior. Students were then asked whether participating in these problem behaviors occurred when under the influence of alcohol. Subjects were post-tested using the same survey instrument during their eighth-grade year. Students were identified only by coded number. At each administration of the survey, students were reminded that the information they provided would remain confidential and that their nameswould never be associateddirectly with the data. Students were encouraged to report honestly. Because alcohol was the primary focus of the study and because no biological measure of alcohol was appropriate for adolescents, no “bogus pipeline” procedure was employed as has been done previously in tobacco research (43). With strong assurancesof confidentiality and multiple experiences with data collection activities, honest reporting was expected to be improved (37, 44). Validity of self-reports was not expected to vary by condition. Statistical Analysis
Only data for students present at pre- and post-test were included. For cigarettes, alcohol, and marijuana, use indices for individuals were created by averaging statistically standardized3 items. Reliability for each scale was calculated using Cronbach’s (Y.For the alcohol index, Cronbach 0~‘swere 0.84 for seventhgrade and 0.86 for eighth-grade reports. For the marijuana index, 0~‘swere 0.58 and 0.60 for seventh- and eighth-grade measures,respectively. For tobacco use at seventh and eighth grades, a’s were 0.81 and 0.87. Each use item was also dichotomized. For alcohol, the cumulative life use and 30-day and ‘I-day use items were dichotomized with responsesof never used, only sips, and only sips for religious purposes coded as 0, and more than sips coded as 1. For cigarettes, dichotomization was based on no use or only taking puffs vs more than puffs (whole cigarettes or more). Drunkenness and marijuana use (ever and past 30 days) items were dichotomized with a non-vs-any split. Schools were the unit of assignment; however, the unit of delivery was the classroom. Because reception of the program varied at the classroom level, and becausethe power for detecting differences with school as the unit of analysis was prohibitively low, classroom of program delivery was selected as the unit of analysis. For each index and dichotomized item, classroom means were created by averaging individual reports by classroom. The classroom-level standardized indices are relatively uninterpretable in terms of incidence and prevalence but provide an accurate overall measure of consumption. For dichotomous items, classroom means represent the proportion of individuals who were above the cut-point. A general linear model analysis of covariance approach was used with classroom means for each composite index and for each dichotomous item. Analyses tested for main effects of ResistanceTraining (ResistanceTraining and Combined programs vs Information and Normative Education programs) and Normative 3 Standardization involved statistically adjusting each item so that the mean equaled 0 and the standard deviation equaled 1 using PROC STANDARD in SAS.
420
HANSEN AND GRAHAM TABLE 2 SUBJECT CHARACTERISTICS Rates by program Information only ww--
Resistance Normative training education Program plogram
F values Resistance Combined training program (main effect)
Normative education (main effect)
RT x NE (interaction)
Sex
Female Ethnicity Asian Black Hispanic white
SES Family income * P **p ***p t P
MEDICINE
20,
414-430 (1991)
Preventing Alcohol, Marijuana, and Cigarette Use among Adolescents: Peer Pressure Resistance Training versus Establishing Conservative Norms’ WILLIAM
B.
HANSEN,
PH.D.,*,*
AND
JOHN
W.
GRAHAM,
PH.D.t
*Department of Public Health Sciences, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27103; and tDepartment of Preventive Medicine, School of Medicine, University of Southern California, Los Angeles, California 9ooo7 Background. Two strategies for preventing the onset of alcohol abuse, and marijuana and cigarette use were tested in junior high schools in Los Angeles and Orange Counties, California. The first strategy taught skills to refuse substance use offers. The second strategy corrected erroneous normative perceptions about prevalence and acceptability of use among peers and established conservative groups norms regarding use. Methods. Four experimental conditions were created by randomly assigning schools to receive (a) neither of the experimental curricula (placebo comparison), (b) resistance skill training alone, (c) normative education alone, or (d) both resistance skill training and normative education. Students were pretested prior to the program and post-tested 1 year following delivery of the program. Results. There were main effects of normative education for summary measures of alcohol (P = O.OOll), marijuana (P = 0.0096), and cigarette smoking (P = 0.0311). All individual dichotomous measures of alcohol, marijuana, and tobacco use indicated significant reductions in onset attributable to normative education. There were no significant main effects of resistance shill training. Conclusion. These results suggest that establishing conservative norms is an effective strategy for preventing substance use. 0 1991 Academic Press, Inc.
INTRODUCTION
Alcohol, tobacco, and marijuana have long been known to be drugs of first use (1, 2). Alcohol and tobacco are known to increase long-term risk of disease and premature mortality (3-5). Alcohol use among youth is a risk factor for morbidity and mortality due to accidents (4). In the nation’s current war on drugs, educational programs frequently target these three substances for primary prevention. Research to date has shown great promise for preventing cigarette use among adolescents (620). Fewer studies that have targeted marijuana use have been conducted (9, 11, 12, 14, 16, 21). Nonetheless, there is evidence that programs that prevent the onset of cigarette use also curtail the onset of marijuana use. To date, alcohol use and misuse among adolescents have not been reliably reduced by prevention programming (9, 13, 16, 22-27) although several recent studies suggest small reductions in alcohol use due to preventive efforts (11, 14, 28, 29). Several recent reviews and research reports have expressed serious doubt that ’ Supported by a grant (ROl-AAO6201) from the National Institute on Alcohol Abuse and Alcoholism. 2 To whom reprint requests should be addressed. 414 0091-7435/91$3.00 Copyright ‘0 1991 by Academic Press, Inc. AU rights of reproduction in any form reserved.
SUBSTANCE
USE PREVENTION
415
school-based alcohol prevention is feasible given the widespread acceptance of the behavior (9, 30, 31). Most substance use prevention programs have utilized eclectic strategies, typically with multiple components that defy precise theoretical interpretation. Programs that have been successful to date have tended to include instruction about the nature of peer pressure and skills to resist peer pressure as one component (32). Indeed, even programs that include a number of intervention techniques often ascribe their successprimarily to the impact of teaching students to resist pressure. Nonetheless, the lack of reliable effects on preventing alcohol use and the continual mixing of multiple strategies leads one to question whether peer pressure resistance training, as the single strategy, can account for preventive effects. Particularly, it is possible that it is the establishment of conservative norms regarding use rather than resistance skills that accounts for lower use among particular subgroups (33). Ironically, peer pressure resistance training programs have been consistently confounded with other programmatic strategies that have the potential to establish conservative norms through the correction of erroneous normative beliefs (34). To date, two distinguishable strategies for addressing the issues of social i&hiences have been developed. The first strategy to be tested involves teaching skills to resist peer pressure to use alcohol and other substances. This strategy was developed in responseto the known statistical relationship between substance use among friends and the onset of use among individuals who associate with friendship groups who use (34). Implied by this relationship, and validated to some extent by an examination of the process of onset (35), is the idea that young people perceive peer pressure to participate in substance use in order to be accepted by the peer group. To counter this pressure, programs teach young people to identify situational pressuresto conform to group behavior and teach skills to refuse offers and demands to use while maintaining group membership. The second strategy involves the correction of erroneous perceptions about the prevalence and acceptability of alcohol use. The roots of this strategy are derived from the propensity of young people to overestimate actual prevalence of all forms of substanceuse (34,364O). This overestimation may lead young people to expect use to be normative when, in fact, it is not. This may create an internally generated expectation that the reference group will find use of substances to be desirable and appropriate. To counter this, programs provide students with feedback about actual rates of use and publicize the conservative attitudes toward substance use that exist in the peer group. The Adolescent Alcohol Prevention Trial is an g-year project the purpose of which is to explore the potential of two strategies for deterring the onset of substanceuse in youth. This study involves replicating longitudinal tests of these two strategies in four separate cohorts of students, two cohorts of students that receive programming during the fifth grade, and two that receive initial programming during the seventh grade. This report concerns only the first cohort of seventh-gradestudents. The primary focus of the study was on preventing alcohol use and misuse among adolescents. Cigarettes and marijuana, the use of which correlates with alcohol consumption (l), were also addressed.
416
HANSEN
AND
GRAHAM
METHODS Subjects and Setting
During the 1987-1988school year, 12junior high schools in Los Angeles and Orange Counties, California, were recruited to participate in the study. Prior to delivery of the program, seventh-gradestudents and parents gave informed consent. Experimental Design
Schools were stratified by size, test scores, and ethnic composition and then randomly assigned to receive one of four intervention programs (41). The first program (Information) consisted of four 45-min lessonsabout the social and health consequencesof using alcohol and other drugs. The second program (Resistance Training) consisted of four lessons about the consequences of using substances plus five lessons that taught students to identify and resist peer and advertising pressure to use alcohol and other substances. The third program (Normative Education) included four information lessons plus five lessons that corrected erroneous perceptions of the prevalence and acceptability of alcohol and drug use among peers and established a conservative normative school climate regarding substance use. The fourth program (Combined) included three lessons about information, three and one-half lessons teaching resistance skills, and three and one-half lessons establishing conservative norms. Components of these programs are described in Table 1. These four programs result in two main effects that may be tested: normative education vs no normative education and resistance training vs no resistance training. Programs were delivered entirely by project staff. Program specialists devoted full time effort to teaching. Each had received a minimum of 2 weeks of intensive training. Several had helped with the initial development of both programs and had several years of experience in delivering these types of programs prior to their participation in this study. Previous analyses of the quality of implementation indicate high fidelity of performance (42). Measures
Students were pretested using a questionnaire that assessedtheir use of alcohol, marijuana, and cigarettes. For each of these substances, subjects were asked to report on cumulative lifetime consumption and use during the 30 days prior to the survey. For alcohol, students also reported the number of times they had previously been drunk and their alcohol consumption during the past 7 days. For alcohol measures,responseswere framed in terms of numbers of drinks. Cigarette responseswere framed in terms of numbers of cigarettes. For example, responses to cumulative lifetime alcohol consumption included (a) none or sips (for religious service), (b) sips (not for religious service), (c) part or all of one drink, (d) 2 to 4, (e) 5 to 10, (f) 11 to 20, (g) 21 to 100, and (h) more than 100. Similar scales were constructed for each alcohol and tobacco item. Marijuana items used dichotomous (yes/no) responses.Subjects also reported whether they had discipline problems at school during the previous year and whether they had engagedin violent
Definition of drugs, alcohol is a dw Film/discussion-The Glug (Churchill Films)
Definition of drugs, alcohol is a drug Positive and negative, shortterm, and social consequences of drinking using Socratic Method Parent interview homework, consequences of drinking Prevention Baseballquestion-answer game about consequences of drinking
Question Box-answers to student-generated questions about alcohol and drugs
1
2
4
3
ICU
Session Definition of drugs, alcohol is a dw Positive and negative, shortterm, and social consequences of drinking using Socratic Method Parent interview homework, consequences of drinking Review of consequences, homework Types of social pressure Techniques to refuse Refusal practice Parent interview about peer pressure Assertiveness Role-played refusals
Definition of drugs, alcohol is a dw Positive and negative, shortterm, and social consequences of drinking using Socratic Method Parent interview homework, consequences of drinking Review of consequences, homework Survey about prevalence of alcohol use among students
Survey results Agree/disagree opinion statements Parent interview homework, appropriate/inappropriate alcohol use Class opinions about alcohol use continuum Class discussion of appropriate/ inappropriate alcohol use Nondrinker interview homework-advice
Pressure refusal practice Film/discussion-The Glug
RT
Norm
Curriculum
TABLE 1 PROGRAMCONTENTOFFOVRCVRRKVLA
Types of social pressure Techniques to refuse Refusal practice Parent interview about peer pressure
Survey results Agree/disagree opinion statements
Definition of drugs, alcohol is a drug Positive and negative, shortterm, and social consequences of drinking using Socratic Method Parent interview homework, consequences of drinking Review of consequences, homework Survey about prevalence of alcohol use among students
Combined
Techniques used by advertisers Evaluating alcohol ads Parent/child homework about alcohol advertising Review of homework Develop anti-alcohol advertisements Question box Videotaped commitments to resist pressure to drink alcohol
Developing positive friendships, including nondrinking as a positive quality Prevention Baseball Alcohol rap songs-informal rules about alcohol Question box Videotaped rap songs and personal opinion statements
6
I
8
9
10
Standing up to pressure-report of personal resistance experiences Prevention Baseball
RT
Review of homework Film/discussion-The Glug
Norm
5
Session
Curriculum
TABLE l-Continued
Assertiveness Role-played refusals Parent interview homework, appropriate/inappropriate alcohol use Class opinions about alcohol use continuum Class discussion of appropriate/ inappropriate alcohol use Nondrinker interview homework--advice Techniques used by advertisers Evaluating alcohol ads Parent/child homework about alcohol advertising Alcohol rap songs-informal rules about alcohol Question box Standing up to pressure-report of personal resistance experiences Videotaped rap songs, personal opinion statements and commitments to resist pressure to drink
Combined
SUBSTANCE USE PREVENTION
419
or destructive behavior. Students were then asked whether participating in these problem behaviors occurred when under the influence of alcohol. Subjects were post-tested using the same survey instrument during their eighth-grade year. Students were identified only by coded number. At each administration of the survey, students were reminded that the information they provided would remain confidential and that their nameswould never be associateddirectly with the data. Students were encouraged to report honestly. Because alcohol was the primary focus of the study and because no biological measure of alcohol was appropriate for adolescents, no “bogus pipeline” procedure was employed as has been done previously in tobacco research (43). With strong assurancesof confidentiality and multiple experiences with data collection activities, honest reporting was expected to be improved (37, 44). Validity of self-reports was not expected to vary by condition. Statistical Analysis
Only data for students present at pre- and post-test were included. For cigarettes, alcohol, and marijuana, use indices for individuals were created by averaging statistically standardized3 items. Reliability for each scale was calculated using Cronbach’s (Y.For the alcohol index, Cronbach 0~‘swere 0.84 for seventhgrade and 0.86 for eighth-grade reports. For the marijuana index, 0~‘swere 0.58 and 0.60 for seventh- and eighth-grade measures,respectively. For tobacco use at seventh and eighth grades, a’s were 0.81 and 0.87. Each use item was also dichotomized. For alcohol, the cumulative life use and 30-day and ‘I-day use items were dichotomized with responsesof never used, only sips, and only sips for religious purposes coded as 0, and more than sips coded as 1. For cigarettes, dichotomization was based on no use or only taking puffs vs more than puffs (whole cigarettes or more). Drunkenness and marijuana use (ever and past 30 days) items were dichotomized with a non-vs-any split. Schools were the unit of assignment; however, the unit of delivery was the classroom. Because reception of the program varied at the classroom level, and becausethe power for detecting differences with school as the unit of analysis was prohibitively low, classroom of program delivery was selected as the unit of analysis. For each index and dichotomized item, classroom means were created by averaging individual reports by classroom. The classroom-level standardized indices are relatively uninterpretable in terms of incidence and prevalence but provide an accurate overall measure of consumption. For dichotomous items, classroom means represent the proportion of individuals who were above the cut-point. A general linear model analysis of covariance approach was used with classroom means for each composite index and for each dichotomous item. Analyses tested for main effects of ResistanceTraining (ResistanceTraining and Combined programs vs Information and Normative Education programs) and Normative 3 Standardization involved statistically adjusting each item so that the mean equaled 0 and the standard deviation equaled 1 using PROC STANDARD in SAS.
420
HANSEN AND GRAHAM TABLE 2 SUBJECT CHARACTERISTICS Rates by program Information only ww--
Resistance Normative training education Program plogram
F values Resistance Combined training program (main effect)
Normative education (main effect)
RT x NE (interaction)
Sex
Female Ethnicity Asian Black Hispanic white
SES Family income * P **p ***p t P
