'study extent' is correct and can be used in written English.
You can use it when talking about the amount or degree to which something has been studied or researched. For example, "A recent study conducted by the university examined the study extent of the new vaccine."
Conventional global statistics assume one relationship for the entire study extent, and are not designed to consider whether a relationship varies across space.
In this study, extent of grain processing and intake of ruminal available starch were the most influential factors affecting milk production.
Using a combination of methodologies, carbon farming was a viable land use in over 2.3% of our study extent with a low $5 t CO2e−1 carbon price, and up to 10.5 million hectares (34%) with a carbon price of $50 t CO2e−1.
We compared the top performing models developed for a smaller, nested experimental extent using RF and LR classifiers, and used the best overall model to produce a predictive map of the spatial distribution of L. sinense across our country-wide study extent.
In this study extent analysis of fuzzy AHP is used, as it gives accurate result.
Availability was constrained by image quality, predominantly percentage cloud cover within the study extent.
This paper aims to study the extent to which innovation incentives in a duopoly change according to the extent of product substitutability and the "technological distance" of firms.
Scientists are only now beginning to study the extent of the damage.
To study the extent of retinal vascularization at birth.
She came to the program fully expecting to study the extent to which her bilingual brain was adapted to succeed.
There are no recent studies, largely because corrections officials do not let researchers study the extent of illegal behavior in their institutions.
