Statistical Hypothesis • Null hypothesis (H0): Hypothesis of no difference or no relation (or not guilty) and often has =, ≥, or ≤ notation in the mathematical statement of the hypothesis. A theory about the values of one (or more) population parameter(s). The theory generally represents the status quo, which we accept until it is proven false. Example: H0: μ = 98.6F (average body temperature i...

1 From the Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Mass (K.H.Z., J.R.F., S.G.S., C.M.C.T.); and Department of Health Care Policy, Harvard Medical School, 180 Longwood Ave, Boston, MA 02115 (K.H.Z.). Received September 10, 2001; revision requested November 8; revision received December 12; accepted December 19. Supported in part by Public Health Ser...

Suppose we are using a pH meter to test acidity/alkalinity of a solution used in a manufacturing process. The pH of pure water is 7.00. For samples in the pH range from about 5 to 9 the meter gives normally distributed readings with • μ equal to the true pH of the sample and • standard deviation σ = 0.20. The meter is tested each morning to make sure it is operating properly: n = 4 samples of p...

In statistical applications, such as a comparison of two items, it is useful to know whether one item is equivalent to another. Similarly it is often desirable to know whether one item can act as a substitute for another. Applications of the concept of equivalence include blend and flavor modifications of products, substitution of generic drugs for brand-name drugs, modifications of products in...

the Agrin Hypothesis and providing important new infor-Neuroscience Program mation on reciprocal signaling mechanisms that regu-Department of Physiology and late synaptic differentiation (illustrated in Figure 1). Gau-Howard Hughes Medical Institute tam et al. (1996) describe the phenotype of a mouse in University of California, San Francisco which the differentially spliced exons required for ...

The empirical validity of the projeetivity hypothesis for Bulgarian is tested. It is shown that the justification of the hypothesis presented for other languages suffers serious methodological deficiencies. Our automated testing, designed to evade such deficiencies~ yielded results falsifying the hypothesis for Bulgarian: the non-projective constructions studied were in fact grammatical rather ...

Background The risk-adjusted mortality rate (RAMR) is used widely by healthcare agencies to evaluate hospital performance. The RAMR is insensitive to case volume and requires a confidence interval for proper interpretation, which results in a hypothesis testing framework. Unfamiliarity with hypothesis testing can lead to erroneous interpretations by the public and other stakeholders. We argue t...