8  BIS Review 53/2002  Appendix Chart 1A: Differential between main refinancing interest rates in Denmark and the euro area Percent 7 6 5 4 3 2 1 0 apr-92  apr-93  apr-94  apr-95  apr-96  apr-97  apr-98  apr-99  apr-00  apr-01  apr-02  Int erest rat e dif f erent ial  Note:  Bundesbank main refinancing interest rate before 1999.
It also presupposes that the people we ask are telling the truth about their beliefs. And the fact that we are asking at all presupposes that people's expectations about this outcome even matter for the decisions they make. So it's no wonder that in economics, we make much of the usefulness of ‘revealed preferences’ – observing people's actions rather than asking their opinions.