The 24 hour recall technique is common to nine European countries, while the diary is used in five. According to Mr Peter Menneers presentation in Nov-Dec. to ESOMAR , most countries where diary is used for measuring radio audience tend to present higher figures than the countries using 24 hour recall technique. Another conclusion of Mr Peter Menneers presentation was that in UK, the average listening per head measured by RAJAR jumped by 50% when moving from 24 hour recall to 7 day diary. However it never has been possible to have a thorough and consistent comparison between both methods on a same period, in order to eliminate bias and to check whether diary technique always tends to register higher levels than the recall technique when measuring the radio audience. Fortunately, French market provides such a case, since Mediametrie conducted a panel in Jan- Feb 1993 additionnally to the current phone 24 hour recall called 75 000. The role of the panel was not to substituate to the 75 000 recall survey but to analyse the audience flows, accumulation and duplications during a significantly long period, which the 75000 survey cannot afford.