Outputs are the things we do on the way to achieving outcomes. Historically, the biggest 'output' to be measured has been media clippings and other mainstream media coverage.
The result of the outputs provides us with data we can analyse and take to the next stage of measurement - the out-take, or 'did they hear and understand' and, if they did, what happened as a result. Below are some examples. When you are assessing the level of outputs, you need to correlate why that output has been undertaken - what was all that work for? If mainstream media coverage is an output you need to measure, then don't simply count the number of clippings. Undertake a content analysis that looks at tone, sentiment, effectiveness, balance of argument, actions taken etc., then determine if, as an output, the content has moved you any nearer to your objectives, and ultimately, your outcomes.
Out-takes tell us if people have received the message - you might have told a million people about your event, but if only two turn up (and you were aiming for more than two) then your 'output' has not been successful. More than a decade ago, Jim Macnamara devised the Pyramid of PR Research which provides a staged approach to out-take measurement using research and analysis to determine exactly what people have heard and understood as a result of your activities - or outputs. Today, we have the benefit of many technologies that allow us to quickly interact with others to undertake this research. Below is a quick at-a-glance chart with just a tiny fraction of the out-take measures you can consider.