  Background. Architectural smells and code smells are symptoms of bad code or
design that can cause different quality problems, such as faults, technical
debt, or difficulties with maintenance and evolution. Some studies show that
code smells and architectural smells often appear together in the same file.
The correlation between code smells and architectural smells, however, is not
clear yet; some studies on a limited set of projects have claimed that
architectural smells can be derived from code smells, while other studies claim
the opposite. Objective. The goal of this work is to understand whether
architectural smells are independent from code smells or can be derived from a
code smell or from one category of them. Method. We conducted a case study
analyzing the correlations among 19 code smells, six categories of code smells,
and four architectural smells. Results. The results show that architectural
smells are correlated with code smells only in a very low number of occurrences
and therefore cannot be derived from code smells. Conclusion. Architectural
smells are independent from code smells, and therefore deserve special
attention by researchers, who should investigate their actual harmfulness, and
practitioners, who should consider whether and when to remove them.
