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Community Twin Study (CTS) and Longitudinal Twin Study (LTS) Descriptives
Wave | Sample Size - SAM | % Male | Mean (SD) Age | Mean (SD) CPD |
---|---|---|---|---|
CTS Wave 1 | 2005 | 47% | 15.95 (1.73) | NA |
CTS Wave 2 | 1743 | 45% | 21.32 (2.16) | 8.03 (7.49) |
CTS Wave 3 | 1735 | 45% | 26.57 (2.28) | 8.68 (7.23) |
LTS Wave 1 | 752 | 49% | 12.42 (.37) | NA |
LTS Wave 2 | 793 | 47% | 17.26 | 6.59 (6.67) |
LTS Wave 3 | 762 | 47% | 22.81 (1.27) | 7.07 (6.69) |
FTP Targets Descriptives
Wave | Sample Size | % Male | Mean (SD) Age | Mean (SD) Cig Freq* | Mean (SD) Alc Freq* |
---|---|---|---|---|---|
Wave 1 | 440 | 43% | 18.11 (.4) | 1.09 (1.84) | .75 (.89) |
Wave 2 | 440 | 43% | 19.16 (.4) | 1.51 (2.07) | 1.23 (1.1) |
Wave 4 | 440 | 43% | 21.13 (.41) | 1.48 (2.08) | 1.43 (1.06) |
Wave 6 | 440 | 43% | 23.77 (.41) | 1.52 (2.12) | 1.4 (1.03) |
Wave 8 | 440 | 43% | 25.77 (.44) | 1.58 (2.13) | 1.35 (1.03) |
Wave 10 | 440 | 43% | 27.74 (.44) | 1.28 (2.02) | 1.26 (1.01) |
Wave 12 | 440 | 43% | 29.59 (.4) | 1.32 (2.04) | 1.29 (1.06) |
Wave 14 | 440 | 43% | 31.69 (.5) | 1.21 (1.99) | 1.28 (1.06) |
Michigan Longitudinal Study (MLS) Targets and Siblings
Test Wave | Sample Size | % Male | Mean (SD) Age | Mean (SD) CPD | Mean (SD) DPW |
---|---|---|---|---|---|
1 | 332 | 67% | 11.42 (.34) | .17 (.76) | NA |
2 | 345 | 67% | 12.44 (.36) | 2.27 (8.31) | .21 (.61) |
3 | 376 | 73% | 13.45 (.37) | 1.36 (6.11) | .76 (3.27) |
4 | 460 | 69% | 14.43 (.38) | 1.88 (6.37) | .81 (2.79) |
5 | 426 | 67% | 15.46 (.35) | 2.97 (6.67) | 1.93 (4.44) |
6 | 397 | 71% | 16.45 (.35) | 4.15 (7.93) | 3.89 (9.56) |
7 | 415 | 71% | 17.44 (.35) | 2.17 (5.39) | 4.4 (9.88) |
18 | 117 | 57% | 18.39 (.4) | 8.84 (12.41) | 3.11 (6.68) |
19 | 129 | 60% | 19.48 (.44) | 4.38 (7.21) | 4.62 (7.05) |
20 | 163 | 64% | 20.48 (.56) | 4.73 (6.39) | 6.73 (10.25) |
21 | 145 | 61% | 21.47 (.61) | 5.04 (6.9) | 10.17 (14.07) |
22 | 182 | 69% | 22.44 (.36) | 7.24 (8.67) | 10.53 (13.08) |
23 | 172 | 71% | 23.43 (.37) | 9.6 (9.45) | 8.48 (12.07) |
24 | 156 | 63% | 24.44 (.36) | 8.51 (8.85) | 9.17 (14.4) |
25 | 141 | 70% | 25.32 (.82) | 7.91 (7.51) | 8.06 (11.84) |
26 | 142 | 69% | 26.37 (.38) | 10.28 (9.37) | 6.63 (8.67) |
National Longitudinal Study of Adolescent to Adult Health (AddHealth) Descriptives
Wave | Sample Size | % Male | Mean (SD) Age | Mean (SD) CPD | Mean (SD) DPW |
---|---|---|---|---|---|
1 | 20745 | 49% | 16.15 (1.74) | 5.39 (7.92) | .83 (3.02) |
2 | 14738 | 49% | 16.81 (1.62) | 5.51 (8.01) | .98 (3.46) |
3 | 15197 | 47% | 22.36 (1.83) | 10.34 (9.95)* | .91 (1.73) |
4 | 15701 | 47% | 29.1 (1.75) | 9.26 (9.9) | .81 (1.55) |
In CADD sufficient information to calculate CPD was present only at Waves 2 and 3 in LTS and CTS. We used the following questions from the CIDI-SAM (only asked to participants who smoked at least 20 cigarettes in lifetime AND smoked in the past 12 months):
Questions
Recoding and Transforming
Question B1B was recoded from ordinal to numeric variable of days smoked in 365 days using the following conversions.
Combining Variables
The recoded question B1B was then multiplied by B1C, and divided result by 365 to get average cigarettes per day over the last 12 months.
After data cleaning, the distributions of these variables looked like this:
Changes over time to average CPD:
To examine the correlation between computed CPD variables over the waves, measures were log-transformed, controlling for sex.
CTS Variables
Sex-Controlled CTS Cigs Per Day Variable Correlations (Log-Transformed)
Wave 1 Computed | Wave 2 Computed | |
---|---|---|
Wave 1 Computed | 1 | |
Wave 2 Computed | .66 | 1 |
|
LTS Variables
Sex-Controlled LTS Cigs Per Day Variable Correlations (Log-Transformed)
Wave 1 Computed | Wave 2 Computed | |
---|---|---|
Wave 1 Computed | 1 | |
Wave 2 Computed | .2 | 1 |
|
CPD is only available for parents of target individuals (G1 generation). Measures of alcohol/tobacco use frequency only are available for the G2 generation.
Questions
The change over time in frequency by age looks like this (added jitter):
Questions
Wave 1:
Wave 2:
Wave 3:
Wave 4:
Combining Variables The smoking days per month variables were combined with the cigarettes per day variables, then divided by 30 to get a measure of average cigarettes per day over the last month:
The distribution of the CPD variables looked like this:
The change in CPD over time (added jitter) looks like this:
Subjects were assessed over time with different measures in two groups; A1-7 and A18-26. CPD was asked at both time points with the variable CIG3
Questions
Recoding and Transforming
Question CIG3 was recoded from ordinal to numeric using the following conversions (assuming 20 cigarettes/pack).
The distribution of cigarettes per day over test time (Test variable, X axis), which roughly corresponds as 1-7 = 11-17 years, and 18-26 as 18-26 years old (see Descriptives), looked like this (added jitter):
Waves 1-3 of CTS and LTS were used to create drinks per week measures. There is a computed variable for Waves 1 and 2 and a measured variable for Waves 2 and 3:
Computed Variable:
Questions from the CIDI-SAM supplement and the Monitoring the Future (MTF) Questionnaire were used to compute a drinks per week variable for Waves 1 and 2. Individuals who indicated never drinking were set to missing. Individuals who indicated drinking but not in the last 180 days were set to 0.
Recoding and Transforming:
Question MTF7 was recoded from ordinal to numeric variable of drinks at a typical occasion using the following conversions.
Combining variables:
Divided # of days drunk in last 180 by 26 to get days drunk in typical week, then multiplied by recoded # of drinks at typical occasion to get typical drinks per week.
After data cleaning, the distribution of the computed variable looked like this:
Change over time to DPW:
Measured Variable:
Waves 2 and 3 were directly asked in the CIDI-SAM about their drinks per week. Only individuals who indicated drinking at least one drink (at least one of: can or bottle of beer, glass of wine or wine cooler, shot of hard liquor, or mixed drink with liquor) in the last 12 months were asked these questions. Individuals who did not indicate drinking at least one drink in the past month were set to missing.
Questions:
Combining variables:
Used # from C3TOT4 if available, otherwise used # from C2TOT4.
After data cleaning, the distribution of the measured variable looked like this:
Change over time to DPW:
To examine the correlation between computed and measured DPW variables over the waves, measures were left-anchored by adding a constant of 1 to all measures, then log-transformed, controlling for sex.
CTS Variables
Sex-Controlled CTS Drinks Per Week Variable Correlations (Log-Transformed)
Wave 1 Computed | Wave 2 Computed | Wave 2 Measured | Wave 3 Measured | |
---|---|---|---|---|
Wave 1 Computed | 1 | |||
Wave 2 Computed | .15 | 1 | ||
Wave 2 Measured | .15 | .63 | 1 | |
Wave 3 Measured | .05 | .39 | .3 | 1 |
|
LTS Variables
Sex-Controlled LTS Drinks Per Week Variable Correlations (Log-Transformed)
Wave 1 Computed | Wave 2 Computed | Wave 2 Measured | Wave 3 Measured | |
---|---|---|---|---|
Wave 1 Computed | 1 | |||
Wave 2 Computed | -.16 | 1 | ||
Wave 2 Measured | -.4 | .58 | 1 | |
Wave 3 Measured | -.44 | .21 | .26 | 1 |
|
There is no measure of drinking quantity available (beyond binge drinking measures). Frequency measures are available in the G2 generation.
Questions:
The change over time in frequency by age looks like this (added jitter):
Questions
Wave 1:
Question H1TO16: Think of all the times you have had a drink during the past 12 months. How many drinks did you usually have each time?
Wave 2:
Wave 3:
Wave 4:
Recoding and Transforming
Questions H1TO15 and H2TO19 were recoded from ordinal to numeric using the following conversions:
Questions H3TO38 and H4TO35 were recoded from ordinal to numeric using the following conversions:
Combining variables:
The transformed drinking days per year variables were multiplied by the drinks per day variables, then divided by 365 to get an average drinks per day over the last year:
The distributions of the DPW variables looked like this: