Indifference Curve Analysis
In the 1930s a group of economists, including Sir John Hicks and sir Roy Allen, came to believe that cardinal measurement of utility was not necessary. They argued that demand behaviour could be explained with ordinal numbers (that is, first, second, third, and so on). This is because, it is argued, individuals are able to rank their preferences, saying that they would prefer this bundle of goods to that bundle of goods and so on. Finite measurement of utility therefore becomes unnecessary and it's sufficient simply to place in order consumers preference to investigate this we must investigate indifference curves.