Instrumental variable methods are a third analytic approach that estimate the effect of an intervention in observational data without requiring the factors that differ between the intervention groups ...

The goal of comparative effectiveness research is to inform clinical decisions between alternate treatment strategies using data that reflect real patient populations and real-world clinical scenarios ...

Statisticians point out that medical and other observational studies often produce results that are later shown to be incorrect. They now suggest ways to fix the system. S. Stanley Young, assistant ...

The validity and reliability of observational methods for studying medication administration errors (MAEs) were studied. Between January and June 1998, two pharmacists observed consecutive drug ...