What is meant by high quality social science research is the type of research whose philosophical underpinnings, theoretical rationale, research design and methodological choices are coherent.

The research which leads integrity of the society my be termed as high quality social research.

What is "high quality" social science research?

Think it is difficult to measure whether a piece of research is of high quality or not as there is no universal yardstick & individual scholars might rate the piece of research differently based on their different background, discipline, competency & experience etc.  Think a piece of research is consider high quality as long it can contribute to knowledge.