Epidemiology Research International

Research Article

An Epidemiological Model for Examining Marijuana Use over the Life Course

Table 1

Summary of model parameters and data sources for RAND Marijuana Microsimulation Model.
Baseline value(s), or how determinedSource
Demographics
Total population size50,000Assumed
Time stepOne quarterAssumed
Age distributionMatch US noninstitutionalized population of 12-year oldsNSDUH 2004
Gender Match US noninstitutionalized population of 12-year oldsNSDUH 2004
Race/ethnicityMatch US noninstitutionalized population of 12-year oldsNSDUH 2004
Transitions among drug use proclivity states 
Drug use proclivity (none, occasional, regular, and heavy) for those in the community:Initiation determined using synthetic cohorts 
 ages 12–14For proclivity given initiation: assume transitions are independent of previous history. Use cross-sectional probabilities of proclivity states (none, occasional, regular, and heavy)NSDUH 2002–2004
 ages 15–24Varies by age, gender, race/ethnicity, and prior marijuana useNLSY97
 ages 25+Varies by age and prior marijuana useNHSDA 1994b–1998, NSDUH 2004, and NLSY97
Probability that drug treatment will be successful0.2Assumed [24–26]
Probability of drug use proclivity states for those in treatment:
 when treatment is successfulDecrement proclivity by one level each quarter until no use is achievedAssumed
 when treatment is not successfulHold proclivity at same level for a year following treatmentAssumed
Physical location states
Probability of death in the current quarterVaries by age, gender, and race/ethnicityCenters for disease control and prevention
Probability of going to treatment, given alive at +1 and in community:  
 outpatientVaries by ageTEDS, NSDUH 2005, Oregon treatment administrative data, census data
 residentialVaries by ageTEDS, NSDUH 2005, Oregon treatment administrative data, census data
Probability of a new episode of treatment, given alive at +1 and in treatmentVaries by prior treatment history, age, gender, race/ethnicity, and age of first marijuana useOregon administrative treatment data
Probability of remaining in treatment from time t to time +1Varies by prior treatment history, age, gender, race/ethnicity, and age of first marijuana use Oregon administrative treatment data