An Evaluation of the Changes in the Legal Drinking Ages in Michigan UM HSRI-80-67 Alexander C

232 Pages·2005·11.12 MB·English

Tuhicol Rqort Docuni~tati'omP age
I. Rqod No. 2. Cormmmt Accession No.
UM HSRI-80-67
4. Title end Subtitle 5. Repert Date
An Evaluation of the Changes in the
Legal Drinking Ages in Michigan
8. Perbrming Orgar~xationR epor? NO.
' 7. Authds) UM-HSRI-80-67
Alexander C. Wa-g enaar, Richard I. Dou-q lass
1
9. PukingO rpmiaution Nme ad Address 10. Work Unit No.
Highway Safety Research Institute
The University of Michigan 11. Contract or Gront NO.
Ann Arbor, Michigan 48109
13. Type of Report and Period Cowered
October 1, 1979-
12. $onsoring Agency N r ec nd Addr***
~e~temb-e3r0 , 1980
The Office of Substance Abuse Services,
Michigan Department of Pub1 ic Health,
14. Sponsoring Agency Code
Lansing, Michigan 48906
IS. Suppl-tay Notes
16. Abstroct
Michigan reduced its drinking age from 21 to 18 in 1972. Several studies
have reported significant increases in alcohol -related traffic crashes
among drivers affected by the lower drinking age. Michigan raised the
drinking age from 18 to 21 in December 1978. This investigation measured
the effect of the 1978 increase in the legal drinking age in Michigan on the
frequency of a1 coho1 -re1 ated traffic crash involvement among young drivers.
A 20 percent random sample of all reported motor vehicle crashes in the
State of Michigan from 1972 through 1979 was analyzed. Monthly time-series
of these measures were examined for drivers aged 16-17, 18-20, 21-24, and
25-45 using the Box-Jenkins time-series analysis methods. The analyses con-
trol led for long-term trends, seasonality, and other patterns in crash fre-
quency expected to influence the 1979 data.
A1 1 age groups had reductions in non-alcohol -related crashes in 1979.
Alcohol -related crashes increased sl ightly for drivers aged 21-45, while
these crashes decreased significantly for the 18-20-year-old drivers, who
were directly affected by a higher legal drinking age (21) in 1979, 16-17-
year-old alcohol -related crashes a1 so decreased in 1979. The reductions in
general non-alcohol -related crash frequencies, for a1 1 ages, were too small
to account for the siqnificant reduction in alcohol-related crash incidence
for 18-20-year-01 d drivers.
17. Key Words 18. Distribution Stotu.nt
Legal Drinking Age, Traffic Acci-
dents, Alcohol Availabil ity, Time-
Series Analysis, Public Health,
Youth and Alcohol
21- No. of Pages 22. Prtcc
Unclassified Unclassified 21 8

TABLE OF CONTENTS
. . . . . . . . . . . . . . . . . . . . . . . . .
LIST OF TABLES v
. . . . . . . . . . . . . . . . . . . . . . . .
LIST OF FIGURES i x
. . . . . . . . . , . . . . . . . . . . . . . .
ACKNOWLEDGEMENTS x ii
. . . . . . . . . . . . . . . . . . . . . . .
1.0 INTRODUCTION 1
2.0 BACKGROUND LITERATURE, THEORY, AND DEVELOPMENT OF
. . . . . . . . . . . . . . . . . . . . . . . .
HYPOTHESES 7
2.1 Alcohol and Highway Safety Among Youth
2.2 The Legal Drinking Age and Highway Safety
2.3 Conceptual Models for the Prevention of
Alcohol -re1 ated Problems
2.4 Specification of Hypotheses
. . . . . . . . .
3.0 RESEARCH DESIGN AND DATA ANALYSIS METHODS 51
3.1 Research Design
3.2 Operationalization and Data Collection
3.3 Design Validity
3.4 Data Analysis Methods
. . . . . . . . . . . . . . . . . . . . . . . . . .
4.0 RESULTS 77
4.1 An Example of the Box-Jenkins Method: Three-factor-
surrogate Crash Frequency Among Drivers
Aged 18-20
4.2 Time-series Models of Michigan Total Crash
Frequencies, 1972-1 979
4.3 Time-series Models o f Michigan Fatal Crash
Frequencies, 1968-1 979
5.0 THE RAISED LEGAL DRINKING AGE AND AGGREGATE ALCOHOL
. . . . . . . . . . . . . . . . . .
CONSUMPTION IN MICHIGAN 135
5.1 Literature Review
5.2 Method
5.3 Results
5.4 Discussion
. . . . . . . . . . . . . . . . . .
6.0 SUMMARY AND CONCLUSIONS 157
6.1 Summary o f Findings
6.2 Recomendati ons for Research
6.3 Recomnendations for Pub1 i c Pol icy
iii
APPENDIX A: Baseline ARIM Time-series Model Estimation
. . . . . . . . . . . . . . . . . . . . .
Results 169
. . . . . . . . . . . . . . . . .
APPENDIX B: Designvalidity 181
. . . . . . . . . . . . . . . . . . . . . . . . . .
REFERENCES 207
TAB L.ES
3.1 Full Design Matrix Depicting Age Groups, Type of
. . . . . . . .
Accidents, and Operationalized Measures Used 53
4.1 ARIMA Model Estimation Results for the Frequency of
Three-factor-surrogate Crash Involvement Among 18-20
. . . . . . . . . . . . . . . .
Year Old Drivers in Michigan 83
4.2 Initial Estimation Resul ts for Combi ned ARIMAI
Transfer Function Model of Three-factor-surrogate
. . . . . . . . . .
Crash Frequency Among Drivers Aged 18-20 86
4.3 Final Estimation Results for Combined ARIMAITransfer
Function Model of Three-factor-surrogate Crash
. . . . . . . . . . . . .
Frequency Among Drivers Aged 18-20 88
4.4 Final Estimation Results for Combined ARIMAITransfer
Function Model of Had-been-drinking Crash Frequency
. . . . . . . . . . . . . . . . . .
Among Drivers Aged 18-20 95
4.5 Final Estimation Results for Combined ARIMAITransfer
Function Model of Three-factor-surrogate Crash
. . . . . . . . . . . . .
Frequency Among Drivers Aged 16-17 97
4.6 Final Estimation Results for Combined ARIMAITransfer
Function Model of Reported Had-been-drinking Crash
. . . . . . . . . . . . .
Frequency Among Drivers Aged 16-17 99
4.7 Final Estimation Results for Ctambined ARIMA/Transfer
Function Model of Reported Had-not-been drinking
. . . . . . . . . .
Crash Frequency Among Drivers Aged 18-20 101
4.8 Final Estimation Resul ts for Combined ARIMAITransfer
Function Model of Reported Had-not-been drinking
. . . . . . . . . .
Crash Frequency Among Drivers Aged 16-17 103
4.9 Final Estimation Results for Combined ARIMAITransfer
Function Model of Three-factor-surrogate Crash
. . . . . . . . . . . . .
Frequency Among Drivers Aged 21-24 105
4.10 Final Estimation Results for Combined ARIMAITransfer
Function Model of Reported Had-been-drinki ng Crash
. . . . . . . . . . . . .
Frequency Among Drivers Aged 2'1-24 107
4.11 Final Estimation Results for Combined ARIMA/Transfer
Function Model of Three-factor-surrogate Crash
. . . . . . . . . . . .
Frequency Among Drivers Aged 25-45 109
4.12 Final Estimation Resul ts for Combined ARIMA/Transfer
Function Model of Reported Had-been-drinking Crash
. . . . . . . . . . . .
Frequency Among Drivers Aged 25-45 111
4.13 Final Estimation Results for Combined ARIMA/Transfer
Function Model of Reported Had-not-been-drinki ng
. . . . . . . . .
Crash Frequency Among Drivers Aged 21-24 11 3
4.14 Final Estimation Results for Combined ARIMA/Transfer
Function Model of Reported Had-not-been-drinking
. . . . . . . . .
Crash Frequency Among Drivers Aged 25-45 115
4.15 Summary of Transfer Function Estimates of the Impact
of the Raised Legal Drinking Age on a 20 Percent
. . . .
Random Sample of Motor Vehicle Crashes in Michigan 116
5.1 Estimated Baseline Model of Packaged Beer Distribu-
. . . . . . . .
tion: January 1969 Through December 1978 143
5.2 Comparison of Forecasted and Actual Packaged Beer
. . . . .
Distribution: January 1979 Through February 1980 144
5.3 Estimated Base1 ine Model of Draught Beer Distribution:
. . . . . . . . . . . .
January 1969 Through December 1978 148
5.4 Comparison of Forecasted and Actual Draught Beer
. . . . .
Distribution: January 1979 Through February 1980 149
5.5 Estimated Base1 ine Model of Wine Distribution:
. . . . . . . . . . . .
January 1969 Through December 1978 151
5.6 Comparison of Forecasted and Actual Wine Distribution:
. . . . . . . . . . . .
January 1969 Through February 1980 152
A.l ARIMA Model Estimation Results for the Frequency of
Had-been-drinking Crash Invol vement Among 18-20 Year
. . . . . . . . . . . . . . . . .
01 d Drivers in Michigan 170
A.2 ARIMA Model Estimation Results for the Frequency of
Three-factor-surrogate Crash Involvement Among 16-17
. . . . . . . . . . . . . . .
Year Old Drivers in Michigan 171
A.3 ARIMA Model Estimation Results for the Frequency of
Had-been-drinking Crash Involvement Among 16-1 7 Year
. . . . . . . . . . . . . . . . .
Old Drivers in Michigan 172
A.4 ARIMA Model Estimation Results for the Frequency of
Had-not-been-drin ki ng Crash Invol vement Among 18-20
. . . . . . . . . . . . . . . .
Year Old Drivers in Michigan 173
A.5 ARIMA Model Estimation Results for the Frequency of
Had-not-been-drinking Crash Involvement Among 16-1 7
. . . . . . . . . . . . . . . .
Year Old Drivers in Michigan 174
A.6 ARIMA Model Estimation Results for the Frequency of
Three-factor-surrogate Crash Involvement Among 21 -24
. . . . . . . . . . . . . . . .
Year Old Drivers in Michigan 175
A.7 ARIMA Model Estimation Results for the Frequency of
Had-been-drinking Crash Involvement Among 21 -24 Year
. . . . . . . . . . . . . . . . . .
Old Drivers in Michigan 176
A.8 ARIMA Model Estimation Results for the Frequency of
Three-factor-surrogate Crash Involvement Among 25-45
. . . . . . . . . . . . . . . .
Year Old Drivers in Michigan 177
A.9 ARIMA Model Estimation Results for the Frequency of
Had-been-drin ki ng Crash Invol vfement Among 25-45 Year
. . . . . . . . . . . . . . . . . .
Old Drivers in Michigan 178
A.10 ARIMA Model Estimation Results for the Frequency of
Had-not-been-drinking Crash Invol vement Among 21-24
. . . . . . . . . . . . . . . .
Year Old Drivers in Michigan 779
A.ll ARIMA Model Estimation Results for the Frequency of
Had-not-been-drinking Crash Involvement Among 25-45
. . . . . . . . . . . . . . . .
Year Old Drivers in Michigan 180

FIGURES
Major Categories of Causal Factors in Motor-vehicle
. . . . . . . . . . . . . . . . . . . . . . . . .
Collisions 11
. .
Environmental Causal Factors in Motor-vehicle Coll isions 12
. . . .
Vehicular Causal Factors in Motor-vehicle Collisions 13
. . . . . .
Human Direct Causes in Motor-vehicle Collisions 15
Human Conditions and States Identified as Causal
. . . . . . . . . . .
Influences in Motor-vehicle Coll isions 16
Human Predisposing Factors for Motor-vehicle Col 1i sion
. . . . . . . . . . . . . . . . . . . . . . . .
Involvement 17
. . . . . . . . . .
The Bimodal Model of Alcohol Consumption 32
. . . .
The Single Distribution Mode1 of Alcohol Consumption 36
Conceptual Model of the Impact of Changes in the Legal
. . . . . .
Drinking Age on Motor-vehicle Crash Involvement 41
Negative Impact Pattern Estimated by the rsb (1,0,0)
. . . . .
Transfer Function Model With a Step Function Input 68
Positive Impact Pattern Estimated by the rsb (1,0,0)
. . . . .
Transfer Function Model With a Step Function Input 68
Negative Impact Pattern Estimated by the rsb (0,0,0)
. . . . .
Transfer Function Model With a Step Function Input 69
Positive Impact Pattern Estimated by the rsb (0,0,0)
. . . . .
Transfer Function Model With a Step Function Input 69
Negative Impact Pattern Estimatzed by the rsb (l,0,0)
. . . .
Transfer Function Model With a Pulse Function Input 71
Positive Impact Pattern Estimated by the rsb (1,0,0)
. . . .
Transfer Function Model With a Pulse Function Input 71
Frequency of Three-factor-surrogate Crash Involvement
. . . .
Among 18-20 Year Old Drivers in Michigan, 1972-1978 78
4.2 Autocorrelation Function of the Frequency of Three-factor-
. .
surrogate Crash Involvement Among 18-20 Year Old Drivers 80
4.3 Partial Autocorrelation Function of the Frequency of
Three-factor-surrogate Crash Involvement Among 18-20
. . . . . . . . . . . . . . . . . . . . . .
Year Old Drivers 81
4.4 Frequency of Three-factor-surrogate Crash Involvement
. . . .
Among 18-20 Year Old Drivers in Michigan, 1972-1979 89
4.5 Actual and Predicted Frequency of Three-factor-surrogate
Crash Involvement Among 15-20 Year Old Drivers in Michigan,
. . . . . . . . . . . . . . . . . . . . . . . . .
1973-1979 90
4.6 Frequency of Had-been-drinking Crash Involvement Among
. . . . . . .
18-20 Year Old Drivers in Michigan, 1972-1979 94
4.7 Frequency of Three-factor-surrogate Crash Involvement
. . . .
Among 16-17 Year Old Drivers in Michigan, 1972-1979 9 6
4.8 Frequency of Had-been-drinki ng Crash Involvement Among
. . . . . . .
16-17 Year Old Drivers in Michigan, 1972-1979 98
4.9 Frequency of Had-been-drinki ng Crash Involvement Among
. . . . . . .
18-20 Year Old Drivers in Michigan, 1972-1979 100
4.10 Frequency of Had-not-been-drinking Crash Invol vement
. . . .
Among 16-17 Year Old Drivers in Michigan, 1972-1979 102
4.7 1 Frequency of Three-%factor-surrogate Crash Invol vemen t
. . . .
Among 21-24 Year Old Drivers in Michigan, 1972-1979 104
4.12 Frequency of Had-been-drinking Crash Invol vement Among
. . . . . . .
21-24 Year Old Drivers in Michigan, 1972-1979 106
4.13 Frequency of Three-factor-surrogate Crash Involvement
. . . .
Among 25-45 Year Old Drive-rs in Michigan, 1972-1979 108
4.14 Frequench of Had-been-dri nki ng Crash Invol vement Among
. . . . . . .
25-45 Year Old Drivers in Michigan, 1972-1979 7 10
4.15 Frequency of Had-not-been drinking Crash Invol vemen t
. . . .
Among 21-24 Year Old Drivers in Michigan, 1972-1979 112
4.16 Frequency of Had-not-been Drinking Crash Involvement
. . . .
Among 25-45 Year Old Drivers in Michigan, 1972-1979 114
4.17 Frequency of Three-factor-surrogate Fatal Crash Involve-
. .
ment Among 18-20 Year Old Drivers in Michigan, 1968-1979 123