 values (otherwise they would be a <em>constant</em> rather than a variable), but different values of the variable can relate to each other in different ways, which we refer to as <em>scales of measurement</em>. There are four ways in which the different values of a variable can differ.</p>
<ul>
<li><em>Identity</em>: Each value of the variable has a unique meaning.<br />
</li>
<li><em>Magnitude</em>: The values of the variable reflect different magnitudes and have an ordered relationship to one another –