Pew Research Center’s cross-national studies are fielded in a range of polling environments, from countries where telephone surveys are regularly administered to nations where face-to-face surveys are ...

Pew Research Center designed this study to assess the current state of online survey sampling methods – both probability-based and opt-in – and determine their accuracy on general population estimates ...

A French quality of life questionnaire specific to erectile dysfunction (ED), ‘QVS’ for ‘Questionnaire de Vie Sexuelle’, has been developed. This paper describes its validation: item reduction and ...