Summary of descriptive characteristics of finally selected studies.

* The original English questionnaires were translated into two local languages, namely Afrikaans and Sepedi for use with a few learners who were not proficient in English; otherwise the surveys were conducted in English.
** Although all the items of the SOC-13 loaded on three factors, the original three-factor structure of the SOC-13 could not be replicated in this adolescent population. only six out of 13 items were replicated for this population; however, the internal consistency coefficient was similar to that of the SOC-13 when comparing them as a unidimensional scale.
***These studies employed an abbreviated form of SOC-13 scale by removing one item to provide equal number of 4 items to measure three constructs of SOC.
**** This study reported SOC score on a 7-point range.
***** Participants have a wide age range which categorized into groups: Participants were classified into of the following age groups: 20, 30, 40, 50, 60, 70 and 80 years of age. No mean for total or each age group has provided. The age was classified into four categories, 30–39 years old, 40–49 years old, 50–59 years old and 60–64 years old. No mean for total or each age group has provided. The age was classified into four categories 40–49, 50–59, 60–69, and 70–80. No mean for total or each age group has provided.
****** For each behavior SOC was mentioned separately. Refer to table 2 of the article Lindmark et al., 2011 [30].
Summary of descriptive characteristics of finally selected studies.