Direct Observation

The term “non–intrusive” is often used to characterise this technique: Users do what they normally do without being disturbed by the observ e r s . One of the advantages of this method is that users can be observed in the e n v i ronment where the system is normally used. This is why dire c t o b s e rvation is said to have high face validity, also re f e rred to as extern a l validity or ecological validity. However, one must always be aware of the possibility of the so called “Hawthorne Effect”; the fact that people usually p e rf o rm better under observation because of the attention paid to them.