The statistical inferences needed to answer many of the scientific questions addressed in biomedical research take the form of formal hypothesis tests and estimation of effects. For example, a clinical trial can address the question of whether a new therapy is superior to a standard treatment and can provide an assessment of the magnitude of the benefit of the new therapy. This section describes the concepts involved in formal hypothesis testing and estimation, including the interpretation of P-values and confidence intervals.
Sung JJ, Chung SC, Lai CW, Chan FK, Leung JW, Yung My, Kassianides C, Li AK, "Octreotide infusion or emergency sclerotherapy for variceal haemorrhage," Lancet , 342 : 637-41, 1993. pdf here
Newnham JP, Evans SF, Michael CA, Stanley FJ, Landau LI, "Effects of frequent ultrasound during pregnancy: a randomised controlled trial," Lancet, 342: 887-81, 1993. pdf here