To clarify the linked study is attempting to replicate https://dl.acm.org/citation.cfm?id=1070834, THE seminal study in Test Driven Development. Well to be more precise it was replicating an existing replication of that study which failed to replicate the original results. They were trying to modify the design so as to account for issues in the experimental design that may have led to the replicated study being inconclusive.
This is significant because if you were not aware of the failed replication, and believed that TDD was supported scientifically as more productive because of that original study, then you SHOULD be reconsidering its place in your development process. If that isn't the case your opinion is unchanged by these particular results(even in the article inspiring this one the author admits that their opinion was already based on a much more thorough analysis, see: http://neverworkintheory.org/2016/10/05/test-driven-developm...).
Now what I want to know is why people insist on writing articles in this awful conversation format. It wastes a lot of words to make a simple argument poorly.