폐업하지 않은 기업, 즉 대조군이 존재하지 않아 각각의 요인들이 폐업에 미치는 회귀분석을 수행할 수 없었다.
Because there were no companies that did not close, that is, there is no control group, it was not possible to perform a regression analysis of the effects of each factor on the business closure.