The VMx software can track and present the performance over time for all items and segments.
In the example above, we show scores and their confidence intervals to
underline the importance of always checking if differences are significant
before drawing conclusions, for example when an analysis is based on
few interviews.
Confidence intervals for survey-based scores can be quite wide, in customer
surveys typically around +/- 5 points on the 0-100 scale when based on 50 interviews and
around +/- 2 point when based on 300 interviews. In the case above, the true score
may well be 74 and the 71 + 5 = 76 score from Q2 just the result of favourable circumstances.
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