The key question is: How do you know that people older than 65 will
behave differently than people younger than 65?
Remember, there are three ways to build your participant schedule:
Screening, balancing, and analyzing.
By limiting the group to those under 65, you're *screening* out older
participants. You'd only want to do this if you felt that the data you
would collect from these individuals would some how unfairly change
the inferences, opinions, and recommendations the design team would
come to.
Another alternative is to *balance*: have a significant sample of both
older-than-65 and 65-or-younger participants. By balancing, you could
compare the behavioral differences. But that only would make sense to
do if you had evidence that the behavior differences would be
substantial or if you wanted to know if you could exclude the
screening or balancing later, because it wouldn't make a difference.
(For example, with one corporate intranet client, I recommended
balancing the first few studies between both HQ employees and field-
office employees, so we could tell if the two groups behaved
differently. If they do, then we know we have to test both going
forward. If they don't, then we know that HQ employees -- easier for
the team to have access to -- are good surrogates for field-office
employees.)
The third alternative is to just *analyze*: Here, you'd let chance
take it's place. Odds are, in recruiting participants for this study,
you'd end up with a proportional representation of ages if you didn't
pay attention at all. (No one age is more likely to volunteer than
others.) When analyzing, you just take note of what the ages are and
see, once you've collected your data, if you can identify behavioral
differences.
Analyzing is the cheapest as it puts no constraints on the recruitment
process. Balancing is more expensive because you (a) have to
disqualify otherwise qualified candidates based on the criteria and
(b) you have to study more participants because you need reasonable
samples sizes of each segment. Screening is most expensive because
you're throwing away participants and their data.
I always recommend to our clients, if they don't have any idea whether
a factor makes a difference to go the analyze route until they can
clearly tell me why balancing or screening will be worth it.
Long answer. Sorry.
Jared
Jared M. Spool
User Interface Engineering
510 Turnpike St., Suite 102, North Andover, MA 01845
e: [email protected] p: +1 978 327 5561
http://uie.com Blog: http://uie.com/brainsparks Twitter: jmspool
UIE Web App Summit, 4/19-4/22: http://webappsummit.com
On Mar 12, 2009, at 7:44 AM, Todd Zaki Warfel wrote:
If they don't have members over 65, then using them in research
would end up leading to false data, or untruth. If they have people
over 65 and it's significant enough to warrant including them, then
include them.
For example, if they have 5 members out of 1000 who are 65, then
what's the benefit of including someone over 65 over someone who is
62?
On Mar 12, 2009, at 12:04 AM, Jared Spool wrote:
So? Why limit the age range? How does that benefit the research?
Cheers!
Todd Zaki Warfel
Principal Design Researcher
Messagefirst | Designing Information. Beautifully.
----------------------------------
Contact Info
Voice: (215) 825-7423
Email: [email protected]
AIM: [email protected]
Blog: http://toddwarfel.com
Twitter: zakiwarfel
----------------------------------
In theory, theory and practice are the same.
In practice, they are not.
________________________________________________________________
Welcome to the Interaction Design Association (IxDA)!
To post to this list ....... [email protected]
Unsubscribe ................ http://www.ixda.org/unsubscribe
List Guidelines ............ http://www.ixda.org/guidelines
List Help .................. http://www.ixda.org/help
