Before revision:  However, these PCs, which usually reflect the left-right political spectrum, are sometimes uninformative in explaining significant differences in the distribution of the data(e. g., how to categorize a set of highly-moderate voters).
After revision:  However, these PCs, which usually reflect the left-right political spectrum, are sometimes uninformative or unable to identify significant differences in the distribution of the data(e. g., how to categorize a set of highly-moderate voters).