The technology of PPMs is complex and still evolving. Although it seems likely that pilot experiments in the field will take place quite soon, the systems could still be changed before they become fully operational and/or alternative new systems may emerge. While at present there seems no cause for serious concern about the implications of introducing PPMs, ESOMAR will continue to monitor the situation. PPMs are of course only one form of research technique involving the observation of people's behaviour. The Committee is also considering whether other observational techniques raise moral or ethical questions which may call for additional forms of supervision and control.