How to read the table - WAMMI scores are expressed as percentiles which
means that a score of 50, for instance, represents the average score
for the scale: 50% of the websites will get a score of less than 50,
and 50% of websites will get a score of 50 or more. A score of 70
represents the 70th percentile: 70% of the websites will get a score of
less than 70, and 30% will get a score of 70 or higher. Thus the higher
your scores, the more usable your web site is.
Notes
WAMMI Scales:- Please see the Graph of WAMMI Results page
for a description of what the WAMMI scales mean.
Median: - This is the center-point of the array of the individual
scores for each scale. You can see a listing of the actual scores the
users gave on the individual user profiles page. Don't
forget, a score of 50 is an average score, below 50 is below
average, and above 50 is above average.
Mean: - This is the numerical average of the individual scores your
users have rated you at.
Standard Deviation: - The standard deviation expresses the amount of variability
in your data. For this kind of data, a reasonable value for the standard
deviation is 20.00 If all your users are agreed on their evaluations of your
web site, the standard deviations will be smaller. If your users have
divergent opinions, the standard deviations will be much greater. Standard
deviations over 30 suggest you have have two or more groups of
users with very different opinions about the usability of your web site. It is not
uncommon to find that the standard deviations are larger for some
scales than for others. This indicates that there are differences in
the amount of agreement between users about these scales.
Discrepancy between Median and Mean: - It may happen that there is a discrepancy between the
median and the mean for one or two scales. What this indicates is that
you have a small number of users who gave you some artificially high or
low scores. It is wisest not to include these, and the median is the
appropriate way to make the adjustment.
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