Quantitative measures of impact include measurements of journals, authors, and individual articles or book chapters.
Qualitative measures of impact include: service on policy-making bodies, consulting, presentations, etc.
The most appropriate measure depends on the values of the researcher's institution and what the researcher wants to showcase. Sometimes, the tools used, the type of output measured, and the career stage of the researcher can affect the results.
Different disciplines have different ways to assess impact. For example, in the Sciences and Medicine, quantitative factors are more highly regarded than in the Arts and Humanities, while Accounting uses both.