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. So the higher your scores, the more usable your web site is.
Mean: This is the numerical average of the individual scores your respondents 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 respondents are agreed on their evaluations of your web site, the standard deviations will be smaller. If your respondents have divergent opinions, the standard deviations will be much greater.
Standard deviations over 30 suggest you have have two or more groups of respondents 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 respondents about these scales.
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