Topic
Null result
About: Null result is a research topic. Over the lifetime, 94 publications have been published within this topic receiving 1311 citations.
Papers published on a yearly basis
Papers
TL;DR: The concept of a ‘rising tide’ phenomenon being a possible explanation of null results is introduced and how a rising tide may be distinguished from other causes of improvement in both control and intervention groups is discussed.
Abstract: Evaluations of service delivery interventions with contemporaneous controls often yield null results, even when the intervention appeared promising in advance. There can be many reasons for null results. In this paper we introduce the concept of a ‘rising tide’ phenomenon being a possible explanation of null results. We note that evaluations of service delivery interventions often occur when awareness of the problems they intend to address is already heightened, and pressure to tackle them is mounting throughout a health system. An evaluation may therefore take place in a setting where the system as a whole is improving – where there is a pronounced temporal trend or a ‘rising tide causing all vessels to rise’. As a consequence, control sites in an intervention study will improve. This reduces the difference between intervention and control sites and predisposes the study to a null result, leading to the conclusion that the intervention has no effect. We discuss how a rising tide may be distinguished from other causes of improvement in both control and intervention groups, and give examples where the rising tide provides a convincing explanation of such a finding. We offer recommendations for interpretation of research findings where improvements in the intervention group are matched by improvements in the control group. Understanding the rising tide phenomenon is important for a more nuanced interpretation of null results arising in the context of system-wide improvement. Recognition that a rising tide may have predisposed to a null result in one health system cautions against generalising the result to another health system where strong secular trends are absent.
97 citations
TL;DR: The Satellite Test of the Equivalence Principle (STEP) as mentioned in this paper was proposed to advance experimental limits on violations of Einstein's equivalence principle from their present sensitivity of 2 parts in $10−13$ to 1 part in$10−18$ through multiple comparison of the motions of four pairs of test masses of different compositions in a drag-free earth-orbiting satellite.
Abstract: The Satellite Test of the Equivalence Principle (STEP) will advance experimental limits on violations of Einstein's Equivalence Principle from their present sensitivity of 2 parts in $10^{13}$ to 1 part in $10^{18}$ through multiple comparison of the motions of four pairs of test masses of different compositions in a drag-free earth-orbiting satellite. We describe the experiment, its current status, and its potential implications for fundamental physics. Equivalence is at the heart of general relativity, our governing theory of gravity, and violations are expected in most attempts to unify this theory with the other fundamental interactions of physics, as well as in many theoretical explanations for the phenomenon of dark energy in cosmology. Detection of such a violation would be equivalent to the discovery of a new force of nature. A null result would be almost as profound, pushing upper limits on any coupling between standard-model fields and the new light degrees of freedom generically predicted by these theories down to unnaturally small levels.
58 citations
TL;DR: The present findings indicate that the correlation is unimpressive and fails to provide a compelling justification for computing p values and as the significance rule becomes more stringent, the correlation decreases.
Abstract: Some supporters of the null hypothesis significance testing procedure recognize that the logic on which it depends is invalid because it only produces the probability of the data if given the null hypothesis and not the probability of the null hypothesis if given the data (e.g., J. Krueger, 2001). However, the supporters argue that the procedure is good enough because they believe that the probability of the data if given the null hypothesis correlates with the probability of the null hypothesis if given the data. The present authors' main goal was to test the size of the alleged correlation. To date, no other researchers have done so. The present findings indicate that the correlation is unimpressive and fails to provide a compelling justification for computing p values. Furthermore, as the significance rule becomes more stringent (e.g., .01, .001), the correlation decreases.
47 citations
TL;DR: The satellite test of the equivalence principle (STEP) as mentioned in this paper was proposed to advance experimental limits on violations of Einstein's equivalence principles from their present sensitivity of two parts in 1013 to one part in 1018 through multiple comparison of the motions of four pairs of test masses of different compositions in a drag-free earth-orbiting satellite.
Abstract: The Satellite Test of the Equivalence Principle (STEP) will advance experimental limits on violations of Einstein's equivalence principle from their present sensitivity of two parts in 1013 to one part in 1018 through multiple comparison of the motions of four pairs of test masses of different compositions in a drag-free earth-orbiting satellite. We describe the experiment, its current status and its potential implications for fundamental physics. Equivalence is at the heart of general relativity, our governing theory of gravity and violations are expected in most attempts to unify this theory with the other fundamental interactions of physics, as well as in many theoretical explanations for the phenomenon of dark energy in cosmology. Detection of such a violation would be equivalent to the discovery of a new force of nature. A null result would be almost as profound, pushing upper limits on any coupling between standard-model fields and the new light degrees of freedom generically predicted by these theories down to unnaturally small levels.
46 citations
TL;DR: A careful analysis of the 1887 Michelson-Morley experiment as discussed by the authors reveals that strict contraction is not required, and a careful analysis reveals a number of serious inadequacies in many textbook treatments.
Abstract: “Can there be some point in the theory of Mr. Michelson’s experiment which has yet been overlooked?” H. A. Lorentz, letter to Lord Rayleigh, August 1892. One of the widespread confusions concerning the history of the 1887 Michelson–Morley experiment has to do with the initial explanation of this celebrated null result due independently to FitzGerald and Lorentz. In neither case was a strict, longitudinal length contraction hypothesis invoked, as is commonly supposed. Lorentz postulated, particularly in 1895, any one of a certain family of possible deformation effects for rigid bodies in motion, including purely transverse alteration, and expansion as well as contraction; FitzGerald may well have had the same family in mind. A careful analysis of the Michelson–Morley experiment (which reveals a number of serious inadequacies in many textbook treatments) indeed shows that strict contraction is not required.
33 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 2 |
| 2020 | 2 |
| 2019 | 3 |
| 2018 | 5 |
| 2017 | 5 |
| 2016 | 7 |