NOTES: Level of significance of difference between the two years: s = .05, ss = .01, sss = .001.
'-' indicates data not available. '*' indicates less than .05 percent but greater than 0 percent.
Any apparent inconsistency between the change estimate and the prevalence of use estimates for the two years is due to rounding error.
SOURCE: The Monitoring the Future Study, the University of Michigan.
|
Approximate Weighted Ns |
1991 |
1992 |
1993 |
1994 |
1995 |
1996 |
1997 |
1998 |
1999 |
|
8th Grade |
17,500 |
18,600 |
18,300 |
17,300 |
17,500 |
17,800 |
18,600 |
18,100 |
16,700 |
|
10th Grade |
14,800 |
14,800 |
15,300 |
15,800 |
17,000 |
15,600 |
15,500 |
15,000 |
13,600 |
|
12th Grade |
15,000 |
15,800 |
16,300 |
15,400 |
15,400 |
14,300 |
15,400 |
15,200 |
13,600 |
a
For 12th graders only: Use of "any illicit drug" includes any use of marijuana, LSD, other hallucinogens, crack, other cocaine, or heroin, or any use of other narcotics, amphetamines, barbiturates, or tranquilizers not under a doctor's orders. For 8th and 10th graders: The use of other narcotics and barbiturates has been excluded, because these younger respondents appear to overreport use (perhaps because they include the use of nonprescription drugs in their answers).b
For 12th graders only: Data based on five of six forms in 1991-1998; N is five-sixths of N indicated. Data based on three of six forms beginning in 1999; N is one-half of N indicated.c
Inhalants are unadjusted for underreporting of amyl and butyl nitrites; hallucinogens are unadjusted for underreporting of PCP.d
For 8th and 10th graders only: Smokeless tobacco data based on one of two forms for 1991-96 and on two of four forms beginning in 1997; N is one-half of N indicated. MDMA data based on one-third of N indicated due to changes on the questionnaire forms. For 12th graders only: Data based on one form; N is one-sixth of N indicated.e
For 12th graders only: Data based on four of six forms; N is four-sixths of N indicated.f
In 1995, the heroin question was changed in three of six forms for 12th graders and in one of two forms for 8th and 10th graders. Separate questions were asked for use with injection and without injection. Data presented here represent the combined data from all forms. In 1996, the heroin question was changed in the remaining 8th and 10th grade form.g
Only drug use which was not under a doctor's orders is included here.h
For 12th graders only: Data based on two of six forms; N is two-sixths of N indicated.i
For all grades: In 1993, the question text was changed slightly in half of the forms to indicate that a "drink" meant "more than a few sips." The data in the upper line for alcohol came from forms using the original wording, while the data in the lower line came from forms using the revised wording. In 1993, each line of data was based on one of two forms for the 8th and 10th graders and on three of six forms for the 12th graders. N is one-half of N indicated for all groups. Data for 1994-99 were based on all forms for all grades.j
Daily use is defined as use on twenty or more occasions in the past thirty days except for 5+ drinks, cigarettes, and smokeless tobacco, for which actual daily use is measured.