At Hotwire PR is measured using the Hotwire Measurement Architecture which reviews the campaign on three levels.  The first level is business outcome.  In other words, how is the programme impacting your bottom line.

The second level is campaign outcome.  This looks at the outcome of the programme seen in strategic terms.  We start with smart objectives and then we measure these in three different ways:

a) a series of perception audits targeting the relevant media/analysts.
b) using a quantitative tool such as PR Audit.
c) customer surveys and audits.

The last is raw output.  This is the tool that measures the effectiveness of the programme, i.e. how well does your PR budget work for you.  We approach this through giving each campaign activity a specific, tactical target .  We call these deliverables and link them to the budget.