"reflect improvement" is correct and usable in written English.
You can use it to refer to an event or situation in which someone has made progress in a certain area. For example: "The increase in sales reflects improvement in the company's marketing strategy."
In general, most individual items tended to reflect improvement among the groups that improved in ETDRS and worsening among the groups that decline in ETDRS.
The intention of consumers to increase holiday spending may reflect improvement in their financial situation.
Metabolic profiling revealed unaltered glycaemia and triglyceridemia, but GW9508 induced a reduction in insulin levels (Supplementary Table 1), which could reflect improvement in insulin sensitivity.
These gains in earnings expectations seem to reflect improvement in actual earnings opportunities, as admission to this elite school system also enhances learning achievement and college graduation outcomes.
Improvements observed in the general ambulance operations may also reflect improvement throughout the health system as a whole.
Change in disability was measured by MIDAS from the second to the first year (negative change scores reflect improvement).
These comments reflect improvements in writing, understanding of the scientific peer-review process, and reflection on the interdisciplinary nature of evolutionary theory.
These results, in turn, reflect improvements in repair shops, management and labor relations.
They had argued that such rankings would not reflect improvements made since their last peer reviews.
The code version used belongs to the master branch, any additional changes made reflect improvements to code readability.
The World Health Organisation criticised that report, saying some of the information was outdated and did not reflect improvements made with external aid.
