One of the major challenges faced by HR in developing its credibility is showing that it is accountable.
As shown in the graph, taken from McKinsey's 2008 of their 1998 War for Talent report, the fact / perception that we are not accountable for anything important in a business is one of other business leaders' major grips about the function.
It's also easy to see how we have got to this situation - HR is obviously accountable for the quality and effectiveness of HR processes but nobody cares very much about that. More important is the use of these processes, but it needs to be line managers who are accountable for the bulk of this. There's also a need in most businesses to strengthen line managers' accountability for the operation of these processes, which often makes HR wary of taking accountability for HR in case this further reduces the accountability that line managers are taking.
HR is also clearly not accountable for business results (though we do play a role as a support function in helping to produce them.). So if we only focus on activities and business impacts we very naturally end up not taking accountability for anything important, and hence how we have got to where we are.
Outcomes give us a way to square the circle - to take accountability for something important - and actually the most important competitive resource most businesses have at their disposal ie the quality of people and culture, and in particular of organisational capabilities.
I've already referred to the differences between an HR function which talks about activities and one which emphasises outcomes. Well the differences with an HR function that focuses on and takes accountability for outcomes is even more pronounced. For example think about the likely perception and credibility of an HR function which talks about the number of training courses it's running and one which takes accountability ie puts its neck on the line for developing certain difficult to find / train competences in its sales force, or for improving engagement levels by say 5%.
Note that I'm not talking about responsibility - it's still line managers who are responsible for creating the required human capital in their teams. But we can, and I believe we should, take accountability for providing the main and most strategic human capital that our businesses need.