TY - JOUR
T1 - Random Assignment of Schools to Groups in the Drug Resistance Strategies Rural Project
T2 - Some New Methodological Twists
AU - Graham, John W.
AU - Pettigrew, Jonathan
AU - Miller-Day, Michelle
AU - Krieger, Janice L.
AU - Zhou, Jiangxiu
AU - Hecht, Michael L.
N1 - Funding Information:
Portions of this were presented at the Annual Meeting of the Society for Prevention Research, Washington, DC, June 2, 2011. This publication was supported by grant number R01DA021670 from the National Institute on Drug Abuse to The Pennsylvania State University (Michael Hecht, Principal Investigator). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Institutes of Health. (NIH manuscript no. NIHMS272843). J.W.Graham . J. Zhou Department of Biobehavioral Health, The Pennsylvania State University, University Park, PA, USA
PY - 2014/8
Y1 - 2014/8
N2 - Random assignment to groups is the foundation for scientifically rigorous clinical trials. But assignment is challenging in group randomized trials when only a few units (schools) are assigned to each condition. In the DRSR project, we assigned 39 rural Pennsylvania and Ohio schools to three conditions (rural, classic, control). But even with 13 schools per condition, achieving pretest equivalence on important variables is not guaranteed. We collected data on six important school-level variables: rurality, number of grades in the school, enrollment per grade, percent white, percent receiving free/assisted lunch, and test scores. Key to our procedure was the inclusion of school-level drug use data, available for a subset of the schools. Also, key was that we handled the partial data with modern missing data techniques. We chose to create one composite stratifying variable based on the seven school-level variables available. Principal components analysis with the seven variables yielded two factors, which were averaged to form the composite inflate-suppress (CIS) score which was the basis of stratification. The CIS score was broken into three strata within each state; schools were assigned at random to the three program conditions from within each stratum, within each state. Results showed that program group membership was unrelated to the CIS score, the two factors making up the CIS score, and the seven items making up the factors. Program group membership was not significantly related to pretest measures of drug use (alcohol, cigarettes, marijuana, chewing tobacco; smallest p > .15), thus verifying that pretest equivalence was achieved.
AB - Random assignment to groups is the foundation for scientifically rigorous clinical trials. But assignment is challenging in group randomized trials when only a few units (schools) are assigned to each condition. In the DRSR project, we assigned 39 rural Pennsylvania and Ohio schools to three conditions (rural, classic, control). But even with 13 schools per condition, achieving pretest equivalence on important variables is not guaranteed. We collected data on six important school-level variables: rurality, number of grades in the school, enrollment per grade, percent white, percent receiving free/assisted lunch, and test scores. Key to our procedure was the inclusion of school-level drug use data, available for a subset of the schools. Also, key was that we handled the partial data with modern missing data techniques. We chose to create one composite stratifying variable based on the seven school-level variables available. Principal components analysis with the seven variables yielded two factors, which were averaged to form the composite inflate-suppress (CIS) score which was the basis of stratification. The CIS score was broken into three strata within each state; schools were assigned at random to the three program conditions from within each stratum, within each state. Results showed that program group membership was unrelated to the CIS score, the two factors making up the CIS score, and the seven items making up the factors. Program group membership was not significantly related to pretest measures of drug use (alcohol, cigarettes, marijuana, chewing tobacco; smallest p > .15), thus verifying that pretest equivalence was achieved.
KW - Group randomized trial
KW - Missing data
KW - Principal component analysis
KW - Random assignment
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U2 - 10.1007/s11121-013-0403-9
DO - 10.1007/s11121-013-0403-9
M3 - Article
C2 - 23722619
AN - SCOPUS:84904298334
SN - 1389-4986
VL - 15
SP - 516
EP - 525
JO - Prevention Science
JF - Prevention Science
IS - 4
ER -