What does interval data represent?

Interval data is characterized by the fact that it is measured along a scale where each point is placed at equal intervals from one another. This type of data does not have a true zero point, which distinguishes it from ratio data. Instead, interval data is based on a defined range that can be measured from an arbitrary point. This means that while you can indeed quantify differences between values using interval data, you cannot meaningfully state that one value is "twice" another because the zero point does not represent the absence of the quantity being measured.

The emphasis on being measured from an arbitrary point is critical, as this highlights that the starting point of the scale is not absolute but relative, allowing for the comparison of differences between values.