The phrase "overall theory" is correct and usable in written English.
You can use it when referring to an overall concept, perspective, or idea in the field of research you are discussing. For example, "This study provides further evidence to support the overall theory that the two species of birds are closely related."
"The overall theory is extremely sound," Medvedev says.
In their discussions with White House aides, prosecutors have been careful to avoid signaling their overall theory of the case.
The overall theory explaining microbial deterioration of concrete is quite well developed in the literature.
One of the key features of humans, according to his overall theory, is that unlike other species we never lose the curiosity and inventiveness of youth.
It should also help the public and policy makers understand that a cool phase does not mean the overall theory of human-driven warming is flawed, Dr. Trenberth said.
Robert A. Iger, president of the Walt Disney Company, who for years played a role in ABC's coverage of Olympics, said he had one overall theory: "For whatever reason, this Olympics had zero buzz.
An alternative version of non-naturalist realism aims to vindicate mathematical and modal claims as essential parts of our best overall theories of the world.
The theories we have discussed so far aim to be "overall" theories of intrinsic value, theories of intrinsic value all things considered, even if they may make some simplifying assumptions about what is valuable.
As a first step we will identify existing theories in order to develop an initial overall programme theory of appraisal and thus explain how appraisal is supposed to result in its intended outcome.
Overall, reliability theory has an amazing predictive and explanatory power with a few, very general and realistic assumptions.
Overall, the theory is supported.
