The phrase "a lengthy study" is correct and usable in written English.
It can be used to describe a research project or analysis that takes a considerable amount of time to complete or is extensive in nature.
Example: "The researchers conducted a lengthy study on the effects of climate change on marine life."
Alternatives: "an extensive study" or "a comprehensive study".
In 1905 he published a lengthy study of the infrared emission and absorption spectra of numerous elements and compounds.
More recently the military historian Jörg Friedrich published a lengthy study titled "The Fire" ("Der Brand"), which in the space of a few weeks became a best seller.
One middle-school class undertook a lengthy study of the Iliad by focussing on the theme of "rage" and designing a spreadsheet that logged instances of it.
Upon hearing that someone had just published a lengthy study of American niceness, undoubtedly the work of years, my first impulse was to pity her unfortunate timing.
The final decision to remove Goya's name from the painting followed a lengthy study by the Prado expert Manuela Mena, which the museum published yesterday.
But John Young, director of the Queens office of the City Planning Department, insists that a lengthy study was unavoidable for the complex project.
However, given the excellent prognosis of this disease, determining their clinical effect will require a large and lengthy study.
Richard Mays Chairman Aqueduct Entertainment Group New York, Aug. 13, 2009 To the Editor: While I am in agreement with The Times that the Aqueduct racetrack is in need of a makeover, I firmly believe, after lengthy study, that permitting a bustling video lottery terminal parlor there is the best solution anyone has offered to date for developing that site.
Gresham Kávéház, for a more casual lunch overlooking the river, serves Hungarian and "contemporary" dishes anything from a sour cherry soup to chicken paprika, with a dessert counter worthy of lengthy study.
Thomas W. Smith Professor of Medicine Christine Seidman (in red) and Associate Professor of Medicine Elizabeth Karlson (far right), co-authors of a study called OurGenes, OurHealth, OurCommunity, eventually want to enroll 100,000 patients in a lengthy, longitudinal study of the causes of illness, which could help link genetic background to lifestyle and environmental factors.
The low response rate reveals it was difficult to recruit these longitudinal study participants to the sub-sample study, which is perhaps a product of only having recently exposed participants to a lengthy main study interview (which lasted an average 2 hours and 43 minutes [ 18]) and perceptions that their 20-year participation had come to an end.
