Monitoring the Future: A Continuing Study of American Youth (12th-Grade Survey), 2014 (ICPSR 36263)

1. Conducted by the University of Michigan, Institute for Social Research, Survey Research Center.

2. To protect the privacy of respondents, all variables that could be used to identify individuals have been collapsed or recoded in the public use files. These modifications should not affect analytic uses of the public use files.

3. Variables omitted from the Western region questionnaires are noted in each codebook.

4. A user guide is provided with the study documentation. It contains a year-to-year cross-time question index for the MTF 12th-grade surveys, which is sorted by subject area, item reference number, and questionnaire form.

5. Frequency and percentage distributions displayed in the 2014 codebooks are unweighted, rather than weighted by variable "ARCHIVE_WT" (previously named "V5") as they had been in previous years. This change was made to simplify both the production of the codebooks and their interpretation by the analyst.

6. MTF does not release detailed geography codes in its public use files because of the disclosure risk it would cause. The MTF sample is drawn to generate representative samples of the four Census Bureau regions of the country (Northeast, Midwest, South, and West), but it does not generate representative samples of smaller geographic areas such as states, counties, or cities. For additional information about data that is withheld from the public use files please contact MTF directly at mtfinformation@umich.edu.

7. With the approval of the MTF Principal Investigators ICPSR created a series of dichotomous recodes for 10 substances for the three standard time periods (lifetime, past 12 months, and past 30 days). The substances include tobacco, alcohol, marijuana, LSD, other psychedelics, amphetamines, sedatives/barbiturates, tranquilizers, inhalants, and other narcotics. These variables have been placed at the end of the Core data file (DS1). Each variable has the same name and label as the original, but with the addition of the letter "D" at the end of the variable name and the words "(dichotomous recode)" included at the end of the variable label. This was only done for the core file.

8. Using these new dichotomous recode variables ICPSR has created interactive maps to show the weighted response for each dichotomous variable by Census region. To create a map simply select the desired year/grade and question/variable. Then click on "Go". The resulting map will rank the regions by color. The Census region with the darkest shade will show the highest frequency of use. A frequency table is also provided.

2018-02-15 The citation of this study may have changed due to the new version control system that has been implemented. The previous citation was:

• Johnston, Lloyd D., Jerald G. Bachman, Patrick M. O'Malley, John E. Schulenberg, and Richard A. Miech. Monitoring the Future: A Continuing Study of American Youth (12th-Grade Survey), 2014. ICPSR36263-v3. Ann Arbor, MI: Inter-university Consortium for Political and Social Research [distributor], 2017-05-24. http://doi.org/10.3886/ICPSR36263.v3

2017-05-24 The question text for variable V6598 in dataset 7 has been corrected to include additional information. The documentation was changed accordingly.

2016-03-14 The Principal Investigator supplied 8 additional variables for Form 1 (DS0002). These 8 variables are V1102, V1108, V1115, V1116, V1117, V1124, V1125, and V1126.

2015-10-26 ICPSR data undergo a confidentiality review and are altered when necessary to limit the risk of disclosure. ICPSR also routinely creates ready-to-go data files along with setups in the major statistical software formats as well as standard codebooks to accompany the data. In addition to these procedures, ICPSR performed the following processing steps for this data collection:

• Standardized missing values.
• Created online analysis version with question text.
• Checked for undocumented or out-of-range codes.