Additionally, it is believed that because the survey participants were not randomly assigned and sampled, the age and monthly average income of the respondents had a biased effect on the data that was gathered.
또한 수집된 자료의 조사대상자 연령과 월평균 소득 등이 할당 표집되지 않아 편향된 영향을 미쳤을 것으로 사료된다.