Skip to main content

Table 1 Sample demographics by each cohort group and wave

From: The CogBIAS longitudinal study of adolescence: cohort profile and stability and change in measures across three waves

Wave 1
 Cohort Total X1 X2 X3 X4 X5 X6 X7 X8 X9 X10
N 504 15 30 62 47 13 34 119 104 54 26
Mean Age (SD) 13.4 (.7) 12.6 (.4) 11.7 (.3) 13.4 (.3) 13.4 (.3) 12.2 (.4) 12.8 (.3) 14.0 (.4) 13.1 (.3) 14.3 (.3) 13.2 (.3)
Year group 7–9 7–8 7 8 8 7–8 8 9 8 9 8
Gender (% Female) 55% 40% 50% 100% 100% 100% 47% 0% 100% 0% 58%
Ethnicity (% Caucasian) 75% 60% 87% 68% 72% 69% 59% 86% 69% 76% 85%
SES (Median, IQR) 4 (2) 4 (2) 3 (2) 4 (2) 3 (2) 4 (2) 2 (2) 4 (1) 4 (2) 4 (2) 3 (2)
Wave 2
 Cohort Total X1 X2 X3 X4 X5 X6 X7 X8 X9 X10
N 450 9 25 60 40 6 26 109 101 50 24
Mean Age (SD) 14.5 (.6) 14.0 (.4) 13.3 (.3) 14.5 (.3) 14.8 (.3) 13.5 (.2) 14.0 (.3) 15.1 (.4) 14.1 (.3) 15.4 (.3) 14.3 (.3)
Year group 8–10 8–9 9 9 10 8–9 9 10 9 10 9
Gender (% Female) 56% 56% 52% 100% 100% 100% 42% 0% 100% 0% 58%
Ethnicity (% Caucasian) 75% 56% 84% 67% 73% 67% 65% 86% 69% 74% 42%
SES (Median, IQR) 4 (2) 4 (2) 3 (2) 4 (2) 3 (2) 4 (2) 2 (2) 4 (1) 4 (2) 4 (2) 3 (2)
Wave 3
 Cohort Total X1 X2 X3 X4 X5 X6 X7 X8 X9 X10
N 411 8 22 62 37 12 12 92 92 50 24
Mean Age (SD) 15.7 (.6) 15.3 (.4) 14.8 (.3) 15.9 (.3) 15.8 (.3) 14.5 (.4) 15.0 (.3) 16.0 (.4) 15.4 (.3) 16.1 (.3) 15.3 (.3)
Year group 9–11 10–11 10 11 11 9–10 11 11 11 11 10
Gender (% Female) 58% 50% 46% 100% 100% 100% 67% 0% 100% 0% 58%
Ethnicity (% Caucasian) 76% 63% 86% 68% 73% 75% 75% 85% 70% 74% 88%
SES (Median, IQR) 4 (2) 4 (2) 3 (2) 4 (2) 3(2) 4 (2) 2 (2) 4 (1) 4 (2) 4 (2) 3 (2)
  1. Note: Update from the protocol paper (Booth et al., 2017); age has now been coded to two decimal places, and SES (Socio-Economic Status) is the median of both mother and father education level; SD Standard Deviation; IQR Interquartile Range; 11% attrition at Wave 2 and 19% attrition by Wave 3