Introduction - Measuring the User Experience: Collecting, Analyzing, and Presenting Usability Metrics - page 5

Some people distinguish between the terms usability and user experience .
Usability is usually considered the ability of the user to use the thing to carry out
a task successfully, whereas user experience takes a broader view, looking at the
individual's entire interaction with the thing, as well as the thoughts, feelings,
and perceptions that result from that interaction.
In any casual conversation about usability, most people would agree that it's
good to have something that works well and isn't confusing to use. On the other
side of the coin, some companies may intentionally design products to be con-
fusing or frustrating. Fortunately, this is a rare occurrence. For the purposes of
this topic, we will be somewhat idealistic and make the assumption that both
users and designers want products to be easy to use, efficient, and engaging.
User experience can sometimes mean the difference between life and death.
For example, the health industry is not immune to poor usability. Usability
issues abound in medical devices, procedures, and even diagnostic tools. Jakob
Nielsen(2005)citesonestudythatfound22separateusabilityissuesthatcon-
tributed to patients receiving the wrong medicine. Even more troubling is that,
onaverage,98,000Americansdieeveryyearduetomedicalerror(Kohnet al.,
2000).Whiletherearenodoubtmanyfactorsbehindthis,somespeculatethat
usability and human factors are at least partially to blame.
In some very compelling research, Anthony Andre looked at the design of
automatic external defribulators (AEDs)(2003). An AED is a device used to
resuscitate an individual experiencing cardiac arrest. AEDs are found in many
public spaces, such as shopping malls, airports, and sporting events. An AED
is intended to be used by the general public with no background or experi-
ence in life-saving techniques such as CPR. The design of an AED is critical, as
most individuals who are actually using an AED are experiencing it for the first
time, under a tremendous amount of stress. An AED must have simple and clear
instructions, and deliver them in a way that is time sensitive and also mitigates
user errors. Andre's research compared four different AED manufacturers. He
was interested in how each of them performed in terms of users being able to
deliver a shock successfully within a specified time limit. He was also interested
in identifying specific usability issues that were impacting user performance
with each of the machines.
In his 2003 study, he assigned 64 participants to one of four different
machines. Participants were asked to enter a room and save a victim (a man-
nequin lying on the floor) with the AED they were assigned. The results he
found were shocking (no pun intended!). While two machines performed as
expected(0%errorsfromasampleof16participantsforeachmachine),two
othermachinesdidnotfaresowell.Forexample,25%oftheparticipantswho
used one of the AEDs were not able to deliver a shock to the victim success-
fully. There were many reasons for this outcome. For example, participants were
confused by the instructions on how to remove the packaging for the pads that
adhere to the bare chest. Also, the instructions on where to place the electrodes
were somewhat confusing.