vlad1I took the above photo of a disconnected crosswalk in Hampton, Virginia a couple of years ago.  The photo nicely demonstrates the difference between outputs and outcomes, showing a crosswalk that ends up a few feet to the left of the new depressed curb that was built.  To be fair, perhaps the crosswalk marking program hadn’t yet caught up with the depressed curb construction program and they will one day connect.  Notice, however, that the pedestrian who is actually crossing doesn’t trust either the curb depression or the crosswalk but is striking out on his own. How does this demonstrate outputs versus outcomes?  An output is simply a quantity of goods or services produced by an individual, a business or an agency.  An output measure in this case could be defined as the number of crosswalks marked or the number of curbs depressed to meet ADA standards.  Let’s say a transportation agency had a performance measure of the number of new crosswalks installed in a given year.  This would be an example of an output measures.  An outcome, on the other hand, is the ultimate goal or purpose towards which we strive.  If this same transportation agency had instead a performance measure of the reduction in pedestrian accidents at intersections, then this would be an example of an outcome measure.  It would measure progress toward an ultimate goal such as pedestrian safety, but it wouldn’t measure anything that is actually produced by the agency.

A Matter of Control

In the realm of performance based planning and programming (PBPP) the key difference between output and outcome measures can become confused.  The main functional difference in this context is that outputs are within the realm of control of the agency, whereas outcomes are beyond the full control of the agency.  The classic example is in the case of safety.  If safety is the goal of the agency, then some of the outputs that the agency may control to meet that goal might be things like the number of road miles repaired or the number of crosswalks added.  However, there are other factors that influence safety that are not totally within the control of the agency.  To name a few, driver attention, skill or weather conditions are totally outside the control of a transportation agency and yet they influence overall safety.  Therefore, measures such as the number of car accidents or pedestrian injuries are really outcome measures since they include factors that are beyond the agency’s control, whereas measures such as roads repaired or crosswalks installed are output measures since they are wholly within the control of the agency.  The chart below illustrates some examples of output versus outcome measures for transportation:

vlad2In God we trust, all others bring data (W. Edward Deming)

The world of transportation planning nowadays is positively drenched in performance measurement.  With the passage of MAP 21, USDOT will now be establishing a set of performance measures for implementation by states and MPOs in the spring of 2014, and we can all anticipate greater prominence of performance measurement in funding and policy decisions.  In transportation planning, confusion among output and outcome measures can result in a lack of connection between policies and their desired results.  As some have pointed out, this confusion can often be complex and hard to sift through.  For example, should TOD be expressed as an output measure (increase in square footage of development around transit) or an outcome measure (greater economic vitality as a result of transit expansion)?  In either case, an awareness of the key difference between outputs and outcomes will help planners avoid obvious pitfalls.  We can at least learn to distinguish between measuring an output such as the number of crosswalks as something we can control, versus measuring an outcome such as overall safety as something we can only influence but not fully control.

–Vlad Gavrilovic, Cities That Work Blog

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