The phrase "principle issue" is correct and usable in written English.
It refers to the main or most important issue/problem at hand. Example: The principle issue in this project is the lack of funding.
Again, that's a messaging issue, that's not a principle issue".
The principle issue we were having is speed," Carter said.
The principle issue concerns the position of students from England, Wales and Northern Ireland at Scottish universities.
None of the respondents could point out a principle, issue, or aspect that needed to be included, excluded, or changed.
The distribution (class conditional distributions) to which the classifier is to be applied is parameterized by a state vector and the principle issue is to choose a design state that is optimal in comparison to all other states relative to some measure of robustness.
The principle issue with leaders and politicians consciously lying to their constituents is that it prohibits people from making informed and rational choices.
In parameter estimation, the principle issues are the precision of the estimates and the practical reality of the computational burden.
Our justification for using a conditional logistic regression framework for predicting the number of departures was motivated by two principle issues.
However, within geographically smaller countries such as the UK the principle issues of concern are the same, despite the smaller distances involved.
It might be useful to future similar meta-analyses for us to draw attention to the principle issues: We needed to choose one contrast from each study from which to estimate an exposure response relationship.
Data sources: To better understand and manage the risks of PPCPs in the environment, we used the "key question" approach to identify the principle issues that need to be addressed.
