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OCR for page 76
Evaluating Prevention
Program Effects
As we have seen, the theoretical foundations for prevention are based
on three principal approaches: (1) the risk factor approach, implemented
mainly in the primary grades to affect predisposing factors; (2) the develop-
mental approach, which concentrates on the socially reinforcing properties
of classrooms and family environments; and (3) the social learning ap-
proach, working in junior high and middle schools mainly to alter enabling
factors, such as skills and motivation to resist media and peer influence.
All three approaches use the school as the basic vehicle through which
prevention efforts flow, although the stronger examples of each type of
intervention recognize and seek to make positive use of the fact that schools
exist within the context of family and community.
There is a related movement toward the use of mass communications
media as an educational channel. Much of the theoretical foundation for
social influence approaches is transferable to mass media, although commu-
nications experts view the media fundamentally as a supplemental or ampli-
fying rather than the primary carrier of persuasive communications regard-
ing health-related behavior.
The empirical research picture is not as tidy as the theoretical concepts.
For one thing, differences that are sharp and clear in theoretical abstraction
become blurred in the details of application. Most actual school-based
prevention curricula, of whatever theoretical inspiration, include a number
of the following components:
76
OCR for page 77
EVALUATING PREVENTION PROGRAM EFFECTS
77
· Technical information about drugs and the consequences of use,
· Instruction on techniques for making decisions about drug use,
· Clarification of values to help put decisions about drug use in per-
spective,
Instruction in stress management techniques,
Exercises to enhance self-esteem,
Social learning to enhance self-efficacy,
Instruction in setting goals and working to implement them,
Life skills training to assist students in resisting drug use,
Resistance skills training to help students resist pressures, direct and
indirect, to use drugs,
· Making a pledge publicly not to use drugs,
· Instruction in how to set norms for one's age-graded peers and self,
· Instruction in how to provide assistance to one's peers, and
Identification of and encouragement to seek alternatives to drug use.
.
The empirical challenge has been to sort out the critical elements from
the adventitious ones, find the best time to begin intervening, select the
optimal programmatic sequence and emphasis, identify the most conducive
agents of transmission, and divine the most effective ways to prepare those
agents for the task.
The prevention research field is substantial enough, and of long enough
standing, that a number of large-scale, meticulously conducted research evalua-
tions of preventive interventions have been completed; numerous research
reviews and collections of reviews have been published (see, for example,
Goplerud, 1991; Bell and Battjes, 1987; Kumpfer, 19873. Several well-
defined prevention programs have been very widely disseminated. But for
various reasons, the transitions from publication of major results, to compi-
lation of definitive reviews, to wide dissemination of practices have been
less than ideal. Indeed, reading the prevention research literature brings to
mind the Cheshire cat in Lewis Carroll's Wonderland: lines of work seem
to resolve into vivid conclusions, which then fade away in a few critical
turns of the page. The will to believe on the part of implementers and
program sponsors alike seems stronger than the evidence supports.
With this forewarning, we begin the chapter by recounting widely cited
recent meta-analyses of research findings on preventive interventions. To
give more concrete meaning than we think can yet be gained from these
synthetic reviews, we then analyze (1) a series of curricula that use cogni-
tive and behavioral approaches in relatively limited-scale experimental in-
terventions; (2) completed large-scale experimental studies using social in-
fluence programming; (3) prominent work now in progress probing social
influence and developmental interventions; and (4) the special role of mass
media as channels for prevention communications.
OCR for page 78
78
PREVENTING DRUG ABUSE: WHAT DO WE KNOW?
META-ANALYSES OF PREVENTION INTERVENTIONS
Meta-analysis refers to techniques developed by behavioral statisticians
for quantitatively integrating the findings from various studies. These tech-
niques have been described and debated in a number of recent books (e.g.,
Wachter and Straf, 1990) and widely used in the past decade. As Bangert-
Drowns (1988:245), one of the authors reviewed below, points out, meta-
analysis has two potentially major advantages over more traditional narra-
tive reviews of the scientific literature. First, it adheres to a precisely
defined metric of outcome that is comparable across studies: the intervention's
effect size, defined as the difference between the average (mean) scores on
an outcome measure of the experimental and control groups, divided by
their standard deviation. Second, meta-analysis uses reproducible statistical
tests to examine relations between effect sizes and characteristics of the
studies being reviewed.
Two types of meta-analysis have been applied to interventions to pre-
vent drug abuse. Tobler (1986) first employed "classic" meta-analysis (Glass
et al., 1981~. This method sweeps together methodologically loose as well
as rigorous studies, on the grounds that evaluations of methodological strength
differ, and even weak studies contain some increments of information. It
treats separately each of the different numbers of outcome items collected
in different studies, thus allowing some studies disproportionate weight.
Bangert-Drowns (1988) employed"study effect" meta-analysis to examine
school-based substance abuse education. The advantage of the study-effect
approach is that it is more selective, excluding studies with serious method-
ological flaws, and it weights each study equally when average effect sizes
are calculated. In a reanalysis, Tobler (1989) applied the more restrictive
inclusion criteria and weighting used by Bangert-Drowns and then extended
the new analysis by focusing on characteristics of the 10 most effective
programs.
Tobler I
Tobler (1986, 1989) included 143 programs in her first widely cited
meta-analysis. Four criteria were used to include a program in the meta-
analysis:
· Use of quantitative outcome measures including mediating variables;
· Presence of control or comparison groups (however, in many cases
these were supplied by Tobler post hoc);
.
Students in grades 6-12 as recipients of intervention;
· Prevention as a goal of the intervention (i.e., assisting young people
in developing attitudes, values, behavior, and skills that may reduce the
likelihood of drug use).
OCR for page 79
EVALUATING PREVENTION PROGRAM EFFECTS
79
Each program was coded for 17 different content items, which were then
mapped into five program types:
· Knowledge-only, meaning purely informational programs about drug
effects;
· Affective-only, meaning largely nondrug-specific curricula to enhance
self-esteem or general competency skills (see further discussion below);
· Knowledge-plus -affective ;
· Peer programs (which means that some program element focuses on
peer interaction, either as a teaching method or as a transmitter of drug
behavior this does not necessarily mean training in peer resistance skills),
and
.
Alternatives, generally meaning that the subjects were treated out-
side a conventional school environment.
In all, 63 variables (e.g., outcome measures, client characteristics, meth-
odological issues, program implementation, etc.) that could affect program
success were coded. Tobler estimated effect sizes for program success
based on outcome variables for drug knowledge; drug attitudes and values;
behavioral skills (i.e., decision making, assertiveness, refusal, etc.), in terms
of learning the skills and, separately, reporting instances of using them; and
self-reported drug use.
Tobler (1986) found that the average effect size for change in knowl-
edge (0.52) was nearly double the effect for desired change in nondrug
behaviors (0.27), skills development (0.26), and self-reported drug use (0.24~.
The effect size for attitudinal change was the lowest among the outcomes
assessed (0.18~. Knowledge-only programs had measurable effects on knowledge
but negligible effects on attitudes and self-reported drug use. Affective-
only programs were, in Tobler's analysis, ineffective across all outcome
measures. Knowledge-plus-affective programs had a very modest average
effect size on drug use (0.15~. Peer programs had the most marked effect
on self-reported drug use (0.40~. Alternative programs, which were highly
intensive and targeted on high-risk adolescents, were midway between.
Tobler's analysis suggests that a significant effect on drug knowledge
and attitudes can occur without significant parallel changes in drug use.
The analysis also suggests that there are no significant differences in drug
use outcome effects between urban and suburban populations and between
junior and senior high students.
Tobler II
Tobler's original report was critically reviewed by Bangert-Drowns (1988~.
He noted that an unreported number of the evaluations included in Tobler's
analysis were not located in the peer-reviewed literature and, for this and
OCR for page 80
80
PREVENTING DRUG ABUSE: WHAT DO WE KNOW?
other reasons, there were far too many methodologically weak reports in the
pool of studies analyzed. Moreover, he noted that an unspecified number of
the studies did not include sufficient information to calculate effect sizes,
which had led Tobler to improvise various unspecified imputation proce-
dures. Finally, he noted that the overall results gave very disproportionate
weight to a small group of studies with large numbers of outcome measures.
(Note: this is also problematic from a statistical significance testing stand-
point insofar as the samples are not independent.)
Tobler (1989) subsequently reanalyzed 91 of the 143 prevention inter-
vention programs included in the original meta-analysis. The weakest stud-
ies were evidently excluded. This new analysis was based solely on the
self-reported drug use outcome and computed only one effect size for each
program. The effect sizes for knowledge-only, affective-only, and knowl-
edge-plus-affective programs were all insignificant at 0.07 or less. The
effect size on drug use outcome for peer programs was 0.42; for alternatives
it was 0.20. These results were quite similar to those originally reported.
Tobler achieved further specification by focusing on the "top-10" (highest
effect sizes) peer programs. Tobler found certain commonalities here, in
particular an emphatic focus on group interaction and delivery of the inter-
vention by mental health professionals or counselors rather than regular
teachers or peer leaders. The most successful programs for those of junior
high age stressed the acquisition of skills, particularly refusal skills, al-
though there was evidence of efficacy for broad-spectrum (decision making,
competency, life) skills as well. The top peer programs among those of
high school age featured well-structured group discussions that maintained
an emphasis on drugs. Tobler notes that individual sessions often aug-
mented the group sessions.
Based on these results of scrutinizing the top 10, Tobler reanalyzed the
data from the 91 programs and found that overall effect sizes for mental
health professionals or counselors were at least twice the effect size for
health education specialists, peer leaders, teachers, college students/others,
and a combination of mental health professionals or counselors and teach-
ers. Tobler (1989:19) noted: "The success of the peer programs is not
dependent on the leader but is enhanced by the presenter.... Mental health
professionals or counselors were represented almost entirely in the peer
strategies. This combination produced the highest average effect size (0.80~.
When peer leaders or teachers were used in the peer strategies, their aver-
age effect sizes were equivalent (0.31~."
As clear as these results appear, direct scrutiny of the top-10 programs
yields ambiguities and obstacles to generalization that neither Bangert-Drowns's
nor Tobler's reanalysis addresses. One cardinal point is that Tobler's ge-
neric use of the term drug includes cigarettes and that 4 of the top-10 peer
programs (and an uncertain number of others in the sample) focused exclu
OCR for page 81
EVALUATING PREVENTION PROGRAM EFFECTS
81
sively on cigarettes; only 3 of the 10 included measures of alcohol, mari-
juana, or other drugs. Half of the top 10 did not use an experimental design
involving random assignment. Just 2 of the 10 studies drew representative
samples of students experimentally assigned to treatment and control condi-
tions, and in both of those studies the interventions (and outcomes reported)
are specifically on cigarette smoking. In addition, program subjects were
not generally followed up for long; only two had a follow-up period beyond
1 year. Despite Tobler's selectivity, the general methodological rigor and
relevance of the studies included remains low. Although this would not in
itself invalidate the results, a closer look at a handful of the top-10 pro-
grams stipulated by Tobler, those available in peer-reviewed venues and not
restricted to cigarette smoking, provides a revealing perspective on the meta-
analytic results.
One of these programs was reported by Sorensen and Jaffe (19754. It
involved a total of 10 adolescents who were self-recruited to a 14-week,
once-a-week "drug group" organized by a paraprofessional staff member in
a storefront community youth center. Four recruits stopped participating
after one or two sessions (three after a confrontation over coming to group
meetings while intoxicated or in an otherwise disruptive condition); these
four were used as the control group. The other six participants reported
lifetime use of 9 drugs, while early departees averaged 14 drugs. These
results yield an effect size of 0.71; they were, however, pastiest data. No
pretest data had been collected to ascertain whether control and treatment
groups had different drug experiences even before the intervention, which
the reasons given for the creation of the "dropout" control group certainly
suggest.
In a second top-10 program, Wunderlich et al. (1974) reported on a
procedure instituted in a juvenile court, in which short-term group therapy
was prescribed for adolescents and their parents. The treated group of 100
parent-child cases comprised juvenile drug offenders 14-19 years old (aver
age age 16.6), three-fourths of whom had been detained specifically on drug
charges; 85 percent of their parents participated in 12-week parent groups
(which were separate from those for the adolescents). The 100 comparison
cases were juvenile offenders 9-18 years old (average age 15), 62 percent of
whom had been detained for nondrug-related felony offenses and 33 percent
for the status offense "in need of supervision." All of the comparison group
were referred to detention centers, forestry camps, or juvenile services pro-
bation. At 2-year follow-up, the comparison group (although nearly two
grades younger) had left school more often (25 versus 15), been rearrested
more often on nondrug offenses (41 versus 11), and had more drug rearrests
(3 versus 2) the last statistic yielding an effect size of 0.62.
In Tobler's third top-10 study, Chambers and Morehouse (1983:84-85)
reported on a school-based student assistance program in which counse
OCR for page 82
82
PREVENTING DRUG ABUSE: WHAT DO WE KNOW?
lore with master's degrees conducted individual, family, and group ses-
sions for students. The program was publicized by counselor presenta-
tions in classrooms and letters sent home. According to the authors, "Ex-
cept for students referred . . . because they were caught using alcohol or
drugs, participation is voluntary." About 70 percent of the students in the
program were classified as alcohol or drug abusers. How many of these
were mandatory referrals is unclear. Details of the evaluation procedure
are quite sketchy in the published report, and it is not clear what com-
prised a control group. Based presumably on unpublished data, Tobler
calculated an effect size of 0.94.
The fourth top-10 study was the only one of the four employing a
persuasively equivalent control group of reasonable size against which the
program effect size was inferred, and it was the only one using a sample of
students generalizable to most school settings (although not to the general
population of students). In this study, Horan and Williams (1982) reported
an experiment in which the least assertive one-third of girls and boys, re-
spectively, in an 8th grade cohort were randomly assigned to three condi-
tions: active treatment, "placebo" sessions (both types administered by
master's-level counselors), or no treatment. The students were tested just
prior to the intervention, immediately after the intervention, and again at a
3-year follow-up. The active treatment consisted of five 45-minute sessions
of assertion training over a 2-week period, each session involving three new
exercises (one of which was a peer-pressure-to-use-drugs type of stimulus)
and live modeling, role-playing, and correction of the assertive response.
The placebo sessions were comprised of discussions of assertiveness, peer
pressure, and drug use-but no modeling or role-playing.
There were no pre-post assertiveness effects in the placebo or control
groups, and no 3-year differences between placebo and controls in their use
of alcohol and marijuana or hard drugs. The active training group, how-
ever, gained significantly in pre-post assertiveness, and at 3-year follow-up
they reported three times as many total refusals and one-third as many total
episodes of using drugs; however, the many zero reports and high variance
in quantities marginalized the statistical significance of these results.
In summary, of the four top-10 peer programs reported in accessible,
refereed publications, only the one (Horan and Williams) engenders scien-
tific confidence on the basis of a sound design and here, the result for
which effect size was calculated was statistically suspect. Even more trouble-
some than the prevailing methodological defects is the fact that these inter-
ventions are not, by and large, drug prevention programs as the term is
generally understood. Admission to three of the four programs just re-
viewed required substantial levels of drug-related problems to begin with;
even the fourth program was quite selective, excluding two-thirds of stu-
dents. Calling these interventions prevention rather than treatment or reha
OCR for page 83
EVALUATING PREVENTION PROGRAM EFFECTS
83
bilitation is difficult to justify. The fact that counseling professionals pro-
duced better results would certainly be expected if the programs were in
fact therapeutic rather than prophylactic interventions.
Tobler's results in favor of peer programs that is, interventions refer-
ring to peer interaction as a teaching or therapeutic method may be con-
sidered suggestive to the degree that where there is smoke, even smoke
amplified by mirrors, there may be fire. There is certainly a marked con-
trast between the positive peer results and the uniformly negative results
found with three other types of interventions. Nevertheless, when closely
examined, the fruits of Tobler's meta-analysis can be considered imagina-
tive and provocative but hardly persuasive concerning the question of how
effective prevention programs may be.
Other Meta-Analyses
Bangert-Drowns studied a selection of educational programs much more
tightly screened than Tobler's. He limited the analysis to studies meeting
the following stringent criteria: the programs had to be conducted in schools
with "traditional students", tobacco-only programs were excluded; a no-
treatment control had to be used that was shown not to be significantly
different before treatment from the experimental group; and the original
data had to be reported in sufficient detail to permit unambiguous calcula-
tion of effect sizes.
Under these selection criteria, only 33 programs were admitted to the
meta-analysis. Most were knowledge-only or knowledge-plus-affective pro-
grams, in Tobler's terms, and most used teachers to deliver the intervention.
In all, 4 were in elementary schools, 12 in junior high or middle schools,
and 17 in high school or college. Slightly over half the interventions fo-
cused exclusively on alcohol education, and half were of 5 weeks' duration
or less. The evaluations employed three outcome criteria: knowledge about
substances (alcohol or drugs); attitudes toward substances, their use, and
abuse; and behavior with regard to substances. Of them, 26 evaluations
measured knowledge, 18 measured attitudes, and 14 measured behavior;
only 3 studies measured all three criteria (Bangert-Drowns, 19881.
Effects on knowledge were highest (average effect size 0.76), effects on
attitudes were lower (0.34), and effects on behavior were lowest (0.12), not
differing significantly from zero. No identified study feature had a consis-
tent differential effect on knowledge. However, two program features dif-
ferentially affected attitudinal results: the mode of delivery, with lecture-
only as the weakest mode, and the use of peer leaders, which had significantly
higher average effects in the desired direction compared with adult-led condi-
tions, a result differing from Tobler's. Two study features reliably related
to behavioral outcomes were the year of publication (the more recent the
OCR for page 84
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PREVENTING DRUG ABUSE: WHAT DO WE KNOW?
techniques, the higher the effects) and whether the students volunteered
rather than being forced to participate (volunteers had higher effects).
Bangert-Drowns's sample of evaluations were skewed toward higher
grades, toward an alcohol focus, and toward programs of very short dura-
tion compared with Tobler's selections. Since only a handful of the evalua-
tions included knowledge, attitude, and behavior in the same design, con-
clusions about the relative effect sizes must be viewed with caution.
Bangert-Drowns's exclusion of studies with significant pretreatment differ-
ences between experimental and control groups does not clarify what con-
stituted significant initial nonequivalence in particular, whether statistical
controls over initial conditions were accepted.
Another consideration of the comparison of methods using meta-analysis
is whether the grouping of studies in each category of intervention method
(e.g., cognitive, cognitive-plus-affective) constituted a homogeneous set as
measured by the pretest or pastiest effect sizes. If not, those studies with
extreme effect sizes (outliers) should be removed from the group comparison.
Bruvold and Rundall (1988) published a meta-analysis and theoretical
review of 19 school-based tobacco- and alcohol-oriented intervention stud-
ies. The 19 studies all utilized a control or comparison group and met 5
design criteria. The analysis contrasted the "rational" prevention theory of
Fishbein and Ajzen (1975) with the social reinforcement and learning theory
of Bandura (1977), the social norms/problem behavior theory of Jessor and
Jessor (1977), and the developmental theory of Rosenberg (19791.
Interventions based on the traditional rational teaching model had a
significantly greater effect on knowledge than did the other models. How-
ever, other interventions had greater positive impact on attitudes and to-
bacco and alcohol behavior than the rational model. Bruvold and Rundall
suggest that a threshold change in knowledge is necessary for behavior
change, but attitude changes (in the desired direction) do not necessarily
follow from knowledge changes. A combination of new knowledge and
attitude changes is more certain to produce behavioral results. Traditional
didactic approaches are less effective than other means social reinforce-
ment, normative, or developmental approaches in generating the sequence
of attitudinal and behavioral changes. Bruvold and Rundall concluded (1988:
72-73~: "If an individual receives peer praise and support for refusing
cigarettes, the individual will become fully convinced that such refusals
lead to peer praise and support, a desirable outcome ...." Interventions
targeted at self-esteem enhancement, if they appropriately followed the te-
nets of this theory, would be directed at providing the individual more
constant and explicit feedback from significant other peers.
A meta-analysis by Hansen et al. (1990) was based on 85 distinct co-
horts of subjects. The results reveal that sample retention decreases over
time: the mean proportion of subjects retained in the analyses decreased
OCR for page 85
EVALUATING PREVENTION PROGRAM EFFECTS
85
from 81.3 percent to 67.5 percent from follow-ups taken at 3 months and 3
years, respectively. There was considerable variability in the rates of attri-
tion between studies. The greatest drop in sample retention was found to
occur during the first year of investigation. The authors concluded that
researchers should interpret their results in light of the rate of attrition and
should further their efforts to reduce the rate of attrition. The results of
Project ALERT, discussed later in this chapter, are particularly subject to
this conclusion.
Summary
Tobler's, Bangert-Drowns's, and Bruvold and Rundall's results con-
verge on the general ineffectiveness of knowledge-only, affective-only, and
knowledge-plus-affective programs in affecting alcohol or drug use behav-
iors. Hansen et al. (1990) provide a warning on long-term effects due to the
attrition of subjects over time. Tobler and Bangert-Drowns diverge on what
kind of trainers seem best to induce informational or attitudinal change, but
these results may simply reflect the different kinds of programs analyzed.
Tobler's review suggests that programs oriented toward peer relationships
gain in efficacy, but it leaves open the question of what this advantage
consists of and whether it actually applies to drug prevention programs
among general student populations. The strength of Tobler's meta-analysis
is its overview of different program types, but the strongest conclusion is
difficult to regard as applicable to prevention programs at all. These results
suggest that we need to examine studies of prevention interventions that
employ much more tightly defined contents and more careful scientific de-
signs than appear typical among the types of studies that carry so much
weight in some of the meta-analyses. A good set of cases in point for
preferred studies are the Life Skills Training Program, several studies using
a cognitive-behavioral approach, and the Napa Drug Abuse Prevention Project.
In each case, the research involved programs with discrete modular charac-
teristics, applied to full grade cohorts, within closely controlled experimen-
tal protocols.
THREE PROGRAMS MEETING TOBLER'S CRITERIA
Life Skills Training Program
Life Skills Training (LST) is a middle-school curriculum with three
components (Botvin and Wills, 1985; Botvin and Eng, 1982; Botvin et al.,
1983):
e
Substance-specific information and refusal skills training;
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PREVENTING DRUG ABUSE: WHAT DO WE KNOW?
· A personal skills component to improve critical thinking and respon-
sible decision making, help cope with anxiety, and learn principles of self-
improvement; and
.
Improvement of nonverbal and verbal communication skills for so-
cial encounters including dating, conversation, and assertiveness.
The Life Skills Training program was implemented with booster ses-
sions among a predominantly white sample of 7th grade students who were
followed up in grades 8 and 9 (Botvin et al., 19901. Using a randomized
block design, schools were assigned to receive one of three programs: (1)
the LST program with formal provider training and implementation feed-
back, (2) LST with videotaped provider training and no feedback, or (3) no
treatment. Program outcomes showed significant reduction in smoking and
marijuana use in both experimental conditions at the first and second year
follow-up. The program did not have significant effects on drinking fre-
quency or amount, although at second year follow-up there was a signifi-
cant effect on the frequency of getting drunk for the experimental groups
who received videotape teacher training. The effect was strongest for ciga-
rette use; this is not surprising, as the intervention was originally designed
for smoking prevention. These findings provide the most rigorous test of
the LST approach and demonstrate the effectiveness of LST in reducing
substance-using behaviors among youth in grades 7 to 9.
There is further evidence of short-term efficacy of the LST approach to
drug prevention. The program reduced the proportion of smoking among a
sample of black urban youths by 56 percent in a 3-month pastiest (Botvin et
al., 1989a). A skills training program for smoking prevention was tested in
a predominantly Hispanic population, preliminary evidence supported the
efficacy of the program (Botvin et al., 1989b). These findings suggest that
a preventive approach with some short-term effectiveness in white middle-
class populations may be generalizable to minority populations.
There is some evidence of long-term efficacy using the LST approach
with regard to cigarettes. Smoking prevention integrated into a primary
cancer center prevention strategy with diet modification revealed that the
rate of initiation of cigarette smoking was significantly lower in treatment
schools 6 years following the intervention (Walter et al., 1989~. In grade 4
no smokers were present in the intervention and nonintervention groups; the
rate of initiation of cigarette smoking was 73.3 percent less (3.5 versus 13.1
percent) among youths in the intervention schools than those in noninter-
vention schools; and the effect was stronger for males than for females. An
8-year follow-up study in Finland (North Karelia Youth Project) revealed
that the positive short-term effects on smoking prevalence found immedi-
ately following the intervention and in a 4-year follow-up diminished by the
8-year follow-up. The difference in smoking prevalence, however, remained
OCR for page 108
108
PREVENTING DRUG ABUSE: WHAT DO WE KNOW?
· The mass media can play an important role in creating awareness-
knowledge, in stimulating interpersonal communication, and in recruiting
individuals to participate in campaign activities.
· Interpersonal communication through peer networks is very impor-
tant in leading to and maintaining behavior changes.
.
The perceived credibility of a communication source or channel en
hances the effectiveness of a communication campaign.
.
Formative evaluation can improve the effectiveness of campaigns by
producing messages that are specific to the desired behavior change.
· Campaign appeals that are socially distant from the audience mem-
ber are not effective.
· Campaigns promoting prevention are less likely to be successful than
those with immediate positive consequences.
· Audience segmentation strategies can improve campaign effective-
ness by targeting specific messages to particular audiences. Audience seg-
mentation strategies have focused almost entirely on sociodemographic char-
acteristics or on specific drugs such as cocaine. The next step will be to use
the existing literature on risk and protective factors to identify individuals
at higher risk for drug use or abuse and target messages specifically at these
groups. In fact, this is the basis for the Donohew et al. (1990a' emphasis on
high sensation seeking, an identified risk factor for drug use.
· Timeliness and accessibility of media and interpersonal messages
. . .
can contribute to campaign success.
These characteristics of effective messages provide an important begin-
ning point for future research on media effects on drug use and abuse and in
antidrug prevention campaigns. However, the guiding principle of the en-
tire enterprise has been identified by Roberts and Maccoby (1985:544~:
". . . the ubiquity and assumed homogeneity of media content can make one
forget that meanings are not in messages, but in people."
There are at least three lessons that have been learned from prior re-
search. First, media alone are much less effective than media messages
employed in the context of a broad campaign that includes the use of inter-
personal channels. Second, there is a need for targeting or audience seg-
mentation. Third, there is a strong need for formative research in message
and campaign design.
The media are only one tool in the hands of those concerned with drug
abuse prevention, albeit a very important one.
CONCLUSIONS AND RESEARCH NEEDS
The only way to determine if something really works is to try it, in a
way that permits objective evaluation. Systematic testing and evaluation
are essential to progress in reducing drug abuse. A clear majority of the
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EVALUATING PREVENTION PROGRAM EFFECTS
109
research published as evaluations of the effectiveness of preventive inter-
ventions is methodologically weak. Corrections of their weaknesses is not
a matter of applying rigid formulae. It requires patient commitment to
attracting quality researchers to the field; applying stringent requirements to
publications and research grants, and urging other research sponsors, col-
laborators (such as school administrators), reviewers, and publication edi-
tors to attend to them; developing and supporting appropriate research train-
ing; and attending to socioenvironmental aspects and data quality control
elements of proposed research.
Social Influence Research
Much of the work on social influence approaches to interventions com-
pleted to date has focused on preventing or delaying onset of use of the
gateway drugs. But preventing or delaying onset is only part of the drug
using and abusing continuum. The entire continuum of transitions in drug
use (e.g., initiation, continuation, progression, regression, cessation, relapse)
constitute the proper focus of attention for prevention interventions (Clayton,
1992).
A number of major methodological issues need to be addressed directly
and critically. The first of these is attrition. While attrition rates are often
reported, the analyses usually show demographic and pretest differences on
gross drug use measures between those who remained in the studies and
those who dropped out of the study by treatment condition. Very few
researchers examine or report such differences on the major predictive or
mediating variables. The attrition rates in longitudinal studies on preven-
tion fall below rates achieved by large-scale national studies such as High
School and Beyond, Monitoring the Future, and the National Education
Longitudinal Study. It is essential that panel studies meet attrition stan-
dards that amount to the state of the art in survey research.
A second major methodological issue is statistical power. Most evalua-
tions of prevention interventions suffer from a lack of statistical power to
detect differences. When significant main effects fail to emerge, it is com-
mon to make too much of subgroup differences. A third major method-
ological issue concerns contamination. In the United States, it is virtually
impossible to find a true no-treatment control group. However, none of the
studies describes the prevention intervention received by the so-called con-
trol group members.
Clayton and Cattarello (1990) have identified a series of implementa-
tion issues concerning social influence curricula that should receive atten-
tion. Standards for reporting implementation information scarcely exist,
and too often it is virtually impossible to say what actually occurred in an
intervention (Moskowitz, 1989~. A set of standards such as those discussed
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0
PREVENTING DRUG ABUSE: WHAT DO WE KNOW?
by Clayton and Catalano should be promulgated as an evaluation criterion
for NIDA-sponsored intervention research.
It is clear that different curricula are being used by different research-
ers, but explicit comparisons are just beginning to be made (see Rogers et
al., 1989~. Comparing the efficacy of different social influence programs,
for example, may be comparing the proverbial apples and oranges until
standard descriptive frameworks and measures of what actually occurs in
the classroom are developed, tested, and widely used. There may be differ-
ent pedagogical strategies employed even by teachers or trainers working
from the same book in adjacent classrooms delivering, presumably, the same
lessons. These differences may be systematically related to the different
roles occupied by those delivering the curriculum; to date the evidence on
role effects (peer leaders, health educators, classroom teachers, counselors
or mental health professionals, substance abuse specialists, police officers)
is a raft of inconsistencies. A methodological initiative is needed to de-
velop a gauge of trainers' ability to communicate content accurately, intelli-
gibly, and in ways consistent with the theory intended to be applied by the
intervention.
The skills being taught in these interventions require different levels of
ability for abstraction and specificity. There is little research on how a
single curriculum teaching such skills affects youth in a grade cohort who
have attained different developmental levels. There are few instances in
which research projects have measured actual individual student exposure
to the prevention intervention, to see whether exposure level is connected to
measured outcomes; if there is an individual dose-response effect, this would
substantially raise our confidence that outcomes and program features were
indeed causally linked. It is also important to find some way to assess the
degree to which curriculum is embedded in the school milieu.
Finally, we add our concern to that of Kozlowski et al. (1989:455) and
Flay (1985) about advocacy for social influence interventions in the ab-
sence of even moderately compelling evidence of efficacy.
Ethnicity and Gender: The Neglected Dimensions
Most school-or~ented drug prevention programs are based on mainstream,
one-size-fits-all cultural assumptions. Data on differential effects by ethnicity
of recipient students have been notably scarce in evaluations of major school-
based prevention programs; either no disaggregation by ethnicity is pro-
vided by the evaluators, or the sample sizes for which data are available are
too small for any differential zero-order or partially controlled effects to be
statistically discernible. Differentiation of effects by gender is more com-
mon, and there are glimmers of evidence that prevention programs are more
effective with girls. One might assume that girls are a population that is
OCR for page 111
EVALUATING PREVENTION PROGRAM EFFECTS
111
more compliant to begin with, but assumptions will not take the place of
. . .
c .eeper investigation.
An important exception to the rule of not reporting ethnic results is
Graham and colleagues (1990), who evaluated short-term program effects
of a social influence program (SMART) among Los Angeles 7th graders.
There was a significant program effect for Asian students, nonsignificant
positive effects for Hispanic and black students, and null effects for white
students. There were group differences with respect to different drugs.
Moreover, virtually all positive program effects were among girls, suggest-
ing that gender role norms interact strongly with ethnic group differences.
Koepke et al. (1990) found that in a cigarette smoking prevention and
cessation program addressed to middle school students and their parents in
San Diego and Los Angeles counties (where one-fifth of all Hispanics in the
United States reside), black parents and children were more likely than
white, Hispanic, or Asian ones to assess the parents as potentially effective
in preventing their children from smoking, but Hispanic parents were more
likely to implement "say no" teaching.
School-based drug prevention programs that are not based on one-size-
fits-all models but rather on culturally specific tailoring do exist, and these
have been described to some extent in the literature. Most are adjunctive to
a community-based program; however, none has been satisfactorily evalu-
ated to date using well-designed outcome measures to test their effective-
ness (Orlandi, 1986~. There have been some evaluations among commu-
nity-based prevention programs; for example, Schinke and colleagues (1988)
pilot-tested a program of culturally specific training in competence skills
using random-assignment designs among bicultural Native Americans liv-
ing on reservations; they reported desired effects on drug use prevalence.
We will return to issues of cultural and community specificity in the appen-
dix, where we provide a more elaborate discussion of how research can be
structured to yield more usefully articulated results taking these specifici-
ties into account.
Generic Interventions
Substance abuse is nested within a range of other high-risk activities,
and it is highly plausible that progress in reducing the most serious levels of
illicit drug use will require broad rather than narrow interventions. There is
evidence throughout the prevention literature that training in resistance skills
and information on health risks may be relatively puny if not counterpro-
ductive forces in the lives of many high-risk children, compared with other
problems that may overwhelm them. In studies relevant to substance abuse,
intensive interdisciplinary programs that deal with more central aspects of
their behavior show promise to meaningfully improve the prospects of these
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112
PREVENTING DRUG ABUSE: WHAT DO WE KNOW?
young people, although the specific effects on drug problems are as yet
unknown.
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Representative terms from entire chapter:
program effects
