3.2. Data Collection
The participants of this study were elementary school students. In the study by Mohammadi Zeidi and Pakpour (
14), the frequency of regular breakfast consumption was 40%; thus, P = 0.40, q = 0.60, and z = 2 were included in the following formula.
Since we did not have an accurate estimate of d value (precision), we set it equal to 0.3 p, which by placing in the above formula, the sample size was 66.66 people; however, since the sampling method in the present study was cluster sampling, the value of 4 = design effect was considered, and the final sample size for the study was 268 = 67 × 4. However, considering that about 10% of the questionnaires may be incomplete (m=incomplete questionnaires), the appropriate number of participate to recruit for this study was considered to be 300. After collecting the data, 10 questionnaires were incomplete; thus, the analysis was performed with 290 samples.
Sampling was performed using a multistage method; first, all of the elementary schools (n = 36) were stratified into 2 classes of boy and girl layers. Next, 2 elementary schools were randomly chosen from each layer, and then 4 elementary schools were selected. Finally, 1 grade was randomly selected from each school, and some students who met the inclusion criteria were selected.
The inclusion criterion was elementary students of both sexes who volunteered to participate in the study. According to paragraphs 7, 25, and 26 of the Declaration of Helsinki, to respect the research units, it was not necessary to write the name and surname of the research units when completing the questionnaire, and the results of the research were generally provided to the research units respectively.
The data collection tool was a questionnaire that was previously used by Mohammadi Zeidi and Pakpour (
14). The test-retest method was used to evaluate the reliability of the current population, as well as the reliability of the questionnaire participants. In one of the schools, 20 students were randomly selected and completed the questionnaire. Two weeks later, the same students were asked to complete the questionnaire again. The scores obtained from the first questionnaire (test) and the scores obtained from the second questionnaire (retest) were calculated, and the correlation coefficient was 0.83 between these 2 questionnaires.
The questionnaire included demographic information (age, gender, parents’ educational status, parents’ employment status, and economic status), stages of change in breakfast consumption, decisional balance (perceived barriers and benefits), self-efficacy, and processes of change toward breakfast consumption. To determine stages of change for breakfast at least 2 or more times a week, a questionnaire was used with yes/no responses. It examines the condition or intention of eating breakfast twice a week or more over the next month or 6 months. By answering one of these questions, people were in one of the stages of change. Do you eat breakfast?
□ No, I do not have a tendency to eat breakfast in the following 6 months (precontemplation)
□ No, but I want to eat breakfast in the following 6 months (contemplation)
□ No, but I want to eat breakfast in the following 30 days (preparation)
□ Yes, I have been eating breakfast for < 6 months (action)
□ Yes, I have been eating breakfast alternately for > 6 months (maintenance)
The answers will fall into one of the precontemplation, preparation, contemplation, action, or maintenance stages.
The Perceived Benefits Questionnaire for breakfast consumption contained 15 questions. The answer choices were on a 5-point Likert scale (ranging from 1, not important, to 5, infinitely important) (
5). The score of perceived benefits was summed and then divided by 15. Therefore, the perceived benefits score of breakfast consumption ranged between 1 and 5.
The perceived barriers questionnaire for breakfast consumption contained 7 questions. The answer choices were on a 5-point Likert scale; "not important" (
1) to "infinitely important" (
5). The score of perceived barriers was summed and then divided by 7. Therefore, the perceived barriers score of breakfast consumption ranged between 1 and 5.
The perceived benefits score minus the perceived barriers score to calculate the decisional balance. The internal consistency of this scale determined using Cronbach α was 0.81. The retest coefficient of the test in a sample of 20 subjects was 0.79 weeks.
The Perceived Self-efficacy (PSE) questionnaire for breakfast consumption consisted of 10 items scored on a 5-point Likert scale (ranging from 1, completely incorrect, to 5, completely correct). Cronbach α was 0.92, and the test-retest was 0.82 after 2 weeks.
Change processes include cognitive and behavioral processes. Cognitive processes are empirical processes that emphasize cognitive thoughts, feelings, and experiences and usually occur in the early stages of change and include self-evaluation, dramatic relief, consciousness-raising, re-evaluation of the environment, and social liberation. Behavioral processes focus on behaviors and reinforcers, are more used in the stages of action and maintenance of behavior, and include helping relationships, self-release, mutual conditioning, stimulus control, and strengthening management.
The cognitive processes questionnaire had 12 items scored on a 5-point Likert scale (ranging from 1, never, to 5, regularly). Their scores are added up, followed by dividing by 12. Cronbach α was 0.79, indicating an acceptable internal consistency, and the test-retest was 0.88 after 2 weeks.
The behavioral processes questionnaire had 12 items scored on a 5-point Likert scale (ranging from 1, never, to 5, regularly). Their scores are added up, followed by dividing by 12. Cronbach α was 0.83, indicating an acceptable internal consistency, and the test-retest was 0.87 after 2 weeks.
Before distributing the questionnaires, all necessary notifications were given to the education officials and school administrators, and the students’ identities were kept confidential.