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Table 2 Item characteristics and internal consistencies of modified scales in their final version

From: “läuft.” - a school-based multi-component program to establish a physically active lifestyle in adolescence: study protocol for a cluster-randomized controlled trial

   Pilot study (N = 89)
Scales Number of Items Cronbach’s α Item-rest correlation Item difficulty (in%)
General self-efficacy 5 .83 .58 to .66 60.8 to 68.2
Self-concept: general physical capacity 5 .92 .78 to .83 50.6 to 70.5
Self-concept: physical attractiveness 5 .84 .58 to .71 57.9 to 76.1
Sensation seeking 2 .86   41.0, 43.6
Self-efficacy for physical activity 8 .87 .56 to .78 42.9 to 70.5
Physical activity enjoyment 10 .92 .58 to .85 53.9 to 75.6
Sedentary behavior enjoyment (screen-based)* 4    
Sedentary behavior enjoyment (non-screen-based) 4 .89 .57 to .84 54.2 to 66.4
Parental support for physical activity 2 .79   31.3, 34.8
Psychological well-being 5 .80 .46 to .72 55.3 to 74.4
Physical well-being 2 .70   59.8, 66.1
  1. *In the pilot questionnaire there were two separated scales for TV/DVD time and computer use. Both scales will be combined as overall screen-based sedentary behavior. Hence, there are no item characteristics available for this combined scale.