Measurement Demo Summary

Levels of Measurement

When an interval scale such as sugar content is mapped onto a rating scale such as judgment of sweetness, the resulting rating scale is probably not an interval scale. For most real-world situations, the means of ordinal-level rating scales allow valid conclusions about the direction of the means on the interval scale. However, it is theoretically possible for means on the ordinal scale to be in the opposite direction from means on the interval scale. Experts disagree on the importance of this in real-world data analysis. We believe that the chances of misinterpretation with real data are extremely low, and that it is only with contrived artificial data and mappings of the interval to the ordinal scale that these problems occur.