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Table 5 Overview of source data from three studies and harmonisation process for derivation of ICAD_SchoolTravel3

From: Harmonising data on the correlates of physical activity and sedentary behaviour in young people: Methods and lessons learnt from the international Children’s Accelerometry database (ICAD)

Source data Harmonisation
Study
Wave
Variable(s): name(s), description Summary Category Processing Summary
SPEEDY*
Wave: 1
Variable names:
W1_a2acthrs_clean
W1_a2actmins_clean
W1_a3acthrs_clean
W1_a3actmins_clean
Duration of journey when walking or cycling to school
Continuous variables.
Duration when walking in minutes per day
Mean: 12.7
Median: 10
25th percentile: 5
75th percentile: 15
Range: 0, 60
Duration when cycling in minutes per day
Mean: 11.2
Median: 10
25th percentile: 5
75th percentile: 15
Range: 0, 60
Less than 5 min If duration of walking or cycling <=5 n = 356
6–15 min If duration of walking or cycling = 6–15 (inclusive) n = 432
More than 15 min If duration of walking or cycling >15 n = 193
Missing   n = 1083
KISS
Wave: 1
Variable name: a_schulweg_hin_sommer_time
Duration of journey to school
Continuous variable.
Duration in minutes per day:
Mean: 9.9
Median: 10
25th percentile: 5
75th percentile: 15
Range: 1, 30
Missing, n = 88
Less than 5 min If [a_schulweg_hin_sommer_time] < =5 n = 153
6–15 min If [a_schulweg_hin_sommer_time] = 6–15 (inclusive) n = 249
More than 15 min If [a_schulweg_hin_sommer_time] >15 n = 50
Missing If [a_schulweg_hin_sommer_time] = Missing n = 88
Ballabeina
Wave: 1
Variable name:
W1_a_langeweg
Duration of journey to school
Categorical variable:
<10 min, n = 514
10–20 min, n = 82
>20 min, n = 10
Missing, n = 63
Response categories for this study captured different duration boundaries to those of the harmonised variable and could not be suitably collapsed or otherwise matched. Therefore, this study was not included in the harmonised variable.
  1. For brevity, processing is summarised for data collected at study wave 1 only. Similar procedures were used for subsequent waves. *The SPEEDY questionnaire did not allow for separate estimation of journey duration amongst those who travelled by bus/train or car to school. Therefore, only participants who indicated walk or cycle as their mode of travel were included in his variable