The phrase "allow an incomplete" is correct and usable in written English.
It can be used in contexts where permission is granted for something to be unfinished or not fully completed.
Example: "In this case, we will allow an incomplete submission for the project due to unforeseen circumstances."
Alternatives: "permit an unfinished" or "accept a partial".
Future studies that would allow demographic data to be collected along with the samples may be able to answer questions regarding contact tracing (which is acknowledged as only allowing an incomplete picture of a network due to its reliance on verbal cooperation of patients [26]) using analysis of such clusters.
The chosen incubation conditions only allowed an incomplete digestion, leaving a specific population of partially digested promoter fragments.
Besides lesions that could undoubtedly be classified as benign or malignant, there is a fraction (termed histological underestimates) of histological findings allowing only an incomplete characterisation of the pathology.
One of the most important things Ms. Cobell won in federal court was the right to an accounting as complete as the incomplete trust records would allow — an acknowledgement that the government's obligation to individual trust holders was intact.
On a continental scale, data for certain variables (cultivable area, irrigation techniques, origin of water for irrigation, and irrigated crops) were too incomplete to allow a regional analysis.
The suggested physical model, albeit somewhat incomplete, allows an explanation of some experimental results obtained earlier.
A year later, in April 2006, the roof of the structure was still incomplete, allowing an unobstructed view of the reactor's features.
Of his Raw series, Kivinen tells Creators, it's difficult to allow the incomplete pieces to remain unedited and imperfect: "It's hard to try and learn to love the process as much as the end result... stopping at a pure moment is difficult for me," he says.
