Survey researchers increasingly recognize that a single survey of the general public can rarely represent the views of small groups of Americans. Such surveys frequently have too few interviews with ...

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 ...

The Journal of Geo-information Science recently published an online article on research led by researcher Lianfa Li and researcher Xiaomei Yang (Institute of Geographic Sciences and Natural Resources ...

Background Heart auscultation is a widely used and cost-effective clinical tool for detecting valvular heart disease (VHD), particularly in primary care. However, existing evidence on its diagnostic ...