The OBAFIT project was designed to provide a public tool where PA habits, sedentary behaviors
and the health-related physical fitness of school children from Castilla-La Mancha (a Spanish
region) could be visualized. OBAFIT also allows physical education teachers at participating
schools to monitor and observe the evolution of these variables in their students.
For this, the schooling data provided by the Consejería de Educación, Cultura y Deportes de
la Junta de Comunidades de Castilla-La Mancha (Ministry of Education, Culture and Sports of
the Community Board of Castilla-La Mancha) are considered: the population enrolled in the
region from the first to the sixth year of Primary Education amounts to 131,903 students
(63,488 girls; 68,415 boys) distributed in the five provinces (Albacete 24,143; Ciudad Real
31,053; Cuenca 11,001; Guadalajara 17,560; Toledo 48,146) both in public (106,366) and
private (25,537) schools.
In the case of Secondary Education and the first year of high school, the number of students
stands at 98,745 (50,807 men and 49,267 women) from the five provinces of the region
(Albacete 19,016; Ciudad Real 23,599; Cuenca 8,971; Guadalajara 12,827; Toledo 34,332) of
public centers (80,996) and private (19,078).
The sample size, calculated through the Edidat 4.2 software, is 631 subjects for the Primary
sample and 631 for the Secondary sample (assuming normal distribution). A confidence level of
95% and a margin of error of 3% have been considered, and the CVR associated with low CRC
with a prevalence of 18% is assumed as the parameter of greater variance. If the same level
of confidence and margin of error for both sexes are considered, the sample would amount to
1,262 for each educational level. Assuming a non-response rate of 30%, the final sample size
is estimated at 1640 students in Primary Education and 1640 for Secondary Education.
The participants that will make up the sample will be selected from the 724 Castilian-La
Mancha schools with education in the Primary Education stage, and from 373 Secondary
Education centers. Both public and private centers will be selected. The sample will be
multistage, randomized and stratified according to province (Albacete, Ciudad Real, Cuenca,
Guadalajara and Toledo), area (urban, semi-urban, rural), gender (men, women) and age (one
group for each section of age).
Once the sample size has been determined, a lottery of schools classified based on the
aforementioned criteria is carried out, considering in all cases the proportionality in the
number of students. For this, a multistage method with proportional probability will be used
using SPSS 24.0 software. Approximately 48 centers for Primary Education and 55 for Secondary
Education will be selected, taking into account that there are 6 Primary courses and 4 in
E.S.O. (Spanish system) in addition to 1st year of high school In the selected schools, three
boys and three girls will be randomly chosen per group-class and level, on which the
different instruments will be applied. A priori, due to pedagogical and operational issues in
the administration, proportional age preselection will not be carried out (for the same
group-class). Since all students in the same class-group will have the same probability of
being selected, the age and sex quotas will be corrected at the end of data collection by a
weighting system.