  We present an alternative method of evaluating Quality Estimation systems,
which is based on a linguistically-motivated Test Suite. We create a test-set
consisting of 14 linguistic error categories and we gather for each of them a
set of samples with both correct and erroneous translations. Then, we measure
the performance of 5 Quality Estimation systems by checking their ability to
distinguish between the correct and the erroneous translations. The detailed
results are much more informative about the ability of each system. The fact
that different Quality Estimation systems perform differently at various
phenomena confirms the usefulness of the Test Suite.
