Heads up: teens and drug abuse--understanding the statistics.

Introduction: 2005 Monitoring the Future Survey

* One of scientists' main tools for understanding drug-abuse trends among teens is the annual Monitoring the Future survey. In this survey, approximately 50,000 8th-, 10th-, and 12th-grade students in public and private schools across the country answer questions that provide information about teen drug-abuse behaviors and attitudes. The Monitoring the Future survey has been done essentially the same way for more than 30 years, so scientists trust the trends that the data reveal.

* Students participating in the survey fill out questionnaires in school. (All answers are kept confidential.) Scientists then tally and analyze the answers. They compare the current year's results with those from previous years to see how drug abuse among teens is changing. Armed with these results, scientists can target research and drug abuse prevention efforts in areas that most need them.

* Scientists must take precautions when interpreting the Monitoring the Future results. For example, an increase in the percentage of students saying they've used a particular drug doesn't necessarily mean use of that drug is on the rise. The rise has to be larger than the margin of error, which is an estimate of how a survey would vary if it were taken multiple times using a different group of people each time. Statisticians (mathematicians who study statistics) have devised formulas to determine the margin of error and whether a result is or isn't statistically significant, meaning it didn't happen by pure chance. The formulas take into account sample size (number of people surveyed), the number of possible answers, and the number of people giving each answer. Scientists use the formulas to help them analyze data from surveys such as Monitoring the Future.

Interpreting the Data: Findings From the 2005 Monitoring the Future Survey

Now it's your turn to analyze and interpret statistics from the 2005 Monitoring the Future survey. The two bar graphs below chart 12th-graders' use of two drugs with very 'harmful health consequences: ecstasy and methamphetamine.

Percentage of 12th-grade students saying they used ecstasy at least once in 12 months leading up to the survey

Ecstasy (MDMA): A human-made drug chemically similar to both stimulants and hallucinogens. Research in animals indicates it can damage the brain. In high doses, it can lead to organ damage, including heart failure, and to rare but potentially lethal hyperthermia.

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