The phrase "a major study has found" is correct and usable in written English.
You can use it when referencing the findings or conclusions of a significant research study in a formal or academic context.
Example: "According to recent research, a major study has found that regular exercise significantly improves mental health."
Alternatives: "a significant study has revealed" or "a comprehensive study has shown".
Summer-born children are at a serious disadvantage in the majority of England's primary schools, a major study has found.
Nursing cutbacks are directly linked to higher patient death rates in hospitals, a major study has found.
The Mediterranean diet, with a high fat content from olive oil and nuts, does not cause people to gain weight, a major study has found.
A major study has found no significant improvement during the last ten years in the survival rate of babies born before the current 24-week legal limit for abortion, despite advances in medical care.
Up to $500m£346m6m) spent by the US, EU and other donors to protect the world's second largest swath of rainforest has failed – for the trees, the animals and the people who live among them – a major study has found.
Teenagers who smoke cannabis regularly could be permanently damaging the development of their brain and are likely to end up with significantly lower IQ scores than teenagers who do not use the illicit drug, a major study has found.
At least a dozen major studies have found that early childhood vaccines do not cause autism.
Although no major studies have found a link between the vaccine and autism, the parents have persisted in their legal fight.
Each of them has largely dismissed the idea that thimerosal causes or contributes to autism, and five major studies have found no link.
In the last year, two major studies have found that students in the company's schools typically do no better, and sometimes do worse, than those in comparable district-run schools.
Two major studies have found that PSA testing -- the annual blood test used to screen men for prostate cancer -- saves few if any lives, while exposing patients to treatments that can leave them impotent and incontinent.
