Measuring Scholarly Research Impact: How To Measure Impact?

There are a lot of reasons why people seek to quantify their own or other's research output:

1. Evaluate the impact of your own work for tenure, promotion, hiring.
2. Evaluate the impact of other's work for tenure, promotion, hiring.
3. Compare researchers within in a given field in a more objective manner.
4. Determine what journal to publish in for maximum impact.
5. Identify premier journals in a given field of study.

1. Bibliometrics: within the context of scientific/technical literature, this typically refers to measuring impact by counting citations, specifically by counting how many times a particular work has been cited by other works.
2. Altmetrics: this method attempts to take into account quantifiable measures of impact beyond just citations.  This includes things like mentions on twitter, mentions in blogs, etc.   The idea is to get a fuller picture of impact in an increasingly online research environment.