"companion study" is a perfectly valid combination of words that can be used in written English.
You could use it to describe a research project or paper that is related to a larger research project. For example: "This companion study provides more detailed information on the results of the main study."
A companion study of men's looks would have been nice.
In a companion study, Dr. Assor and his colleagues interviewed mothers of grown children.
A companion study examined carvedilol, a beta blocker; the results indicated that the drug was equally beneficial to both races.
A broader companion study found Professor Ely to be the fourth most frequently cited legal scholar of all time, as judged by references in legal scholarship since 1956.
A companion study of mothers in a low-income, mostly black urban neighborhood found in 1996 that almost half the mothers said their infants usually shared a bed with a parent or other adult caregiver.
In a companion study, a group led by Paul Hayne at the University of California, Los Angeles, used heat sensors on the Lunar Reconnaissance Orbiter to analyse the crash from space.
In a companion study in 2010, Stride polled more than five hundred supporters of World Cup teams and found that "viewers dislike classic cheating a lot more than professional fouls," he said.
Both rates were slightly higher than indicated in a companion study carried out by Norton of Australian women released in March, which found that nearly half – and 76% under 30 – had experienced online abuse.
"Connecticut has attempted 28 times to enact an earned-income tax credit," said Doug Hall, the associate research director of Connecticut Voices for Children, an advocacy group in New Haven that issued a companion study to the report.
The interested reader is referred to this companion study for details [33].
Note that Locations A, B, and C were part of a companion study.
