OA JOURNALS: PUBLISHING METRICS: AN INTRO

Publishing metrics are a category of data employed within publishing environments, and serve various purposes, including:

FOR RESEARCHERS - Metrics are useful for:

• making choices about which journal is most suitable for submitting their work
• assessing and tracking the impact of an individual piece of research over a period of time
   

FOR READERS:  Metrics are useful for:

• Discovering article impact 
• Locating high-ranking journals in the information-seeking/reading process:  Impact factors, citation counts and other data can provide a base for selecting articles to read, journals to follow etc
   

FOR LIBRARIANS:  Metrics are useful for:

• Locating statistical data on which to make journal subscriptions decisions

Source:  Taylor & Francis https://authorservices.taylorandfrancis.com/publishing-your-research/choosing-a-journal/journal-metrics/

PUBLISHERS WARN ABOUT THE LIMITATIONS OF METRICS
Publishers advise that metrics should not be used singularly ie without regard to other information sources
They recommend a "best approach" of employing a number of metrics
 

They also emphasise the value of employing qualitative approaches: 

• referring to the Aims and Scope sections of the journal
• seeking information about a journal's readership
• employing a broad review of the journal eg exploring past issues

Source:  Taylor & Francis Author Services n.d. "Guide to Understanding Journal Metrics" 
https://authorservices.taylorandfrancis.com/publishing-your-research/choosing-a-journal/journal-metrics