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 ...

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 ...

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 ...

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 ...