Levels of measurement On your exam you could be asked to choose which statistical test you would use to test your hypothesis. To do this you need to know THREE methods/levels of measurement within quantitative data, so that you can select the correct statistical test to analyse your data. You need to know whether one group differed SIGNIFICANTLY from another group.

Levels of measurement demonstration Divide yourself into two groups – shorter & taller. Let’s call them short and tall for now. Let’s suppose you are in the tall group – for the moment, all we know about you is that you have the value ‘tall’ and we can’t separate you from the X number of people in your group. All of you get the value ‘tall’ This is our first level of measurement known as NOMINAL The measurement system used on this occasion has just two values, ‘short’ & ‘tall’

Levels of measurement demonstration This time, you need to get into a line in order of your height. Your position in this line is 7 th, next to the tallest person. We call this ORDINAL level of measurement. In nominal level we had no way to separate members of the ‘tall’ group but we know what POSITION you occupy in the group relative to the rest. We still do not have a clue how far below the tallest person you are or how far above the 6 th person in the line.

Levels of measurement demonstration To get the most subtle measure of class height we need a tape measure or wall chart so that we can produce the familiar measurement of height in feet and inches which is known as INTERVAL scale. We can compare you to the general measure of height used everywhere else. We can tell whether you are tall relative to the general population.

Exercise on levels of measurement Activity Complete the exercise on levels of measurement