Introduction to Biostatistics-7 Part II . Inferential Statistics

Http Dx Doi Org 10 1198 000313007x170242, 2012

There is widespread evidence of the extensive use of statistical methods in medical research. Just the same, standards are generally low and a growing body of literature points to statistical errors in most medical journals. However, there is no comprehensive study contrasting the top medical journals of basic and clinical science for recent practice in their use of statistics. All original research articles in Volume 10, Numbers 1-6 of Nature Medicine (Nat Med) and Volume 350, Numbers 1-26 of The New England Journal of Medicine (NEJM) were screened for their statistical content. Types, frequencies, and complexity of applied statistical methods were systematically recorded. A 46-item checklist was used to evaluate statistical quality for a subgroup of papers. 94.5 percent (95% CI 87.6-98.2) of NEJM articles and 82.4 percent (95% CI 65.5-93.2) of Nat Med articles contained inferential statistics. NEJM papers were significantly more likely to use advanced statistical methods (p < 0.0001). Statistical errors were identified in a considerable proportion of articles, although not always serious in nature. Documentation of applied statistical methods was generally poor and insufficient, particularly in Nat Med. Compared to 1983, a vast increase in usage and complexity of statistical methods could be observed for NEJM papers. This does not necessarily hold true for Nat Med papers, as the results of the study indicate that basic science sticks with basic analysis. As statistical errors seem to remain common in medical literature, closer attention to statistical methodology should be seriously considered to raise standards.

Eye, 2011

Purpose To assess the agreement of the optical low-coherence reflectometry (OLCR) device LENSTAR LS900 with partial coherence interferometry (PCI) device IOLMaster and applanation and immersion ultrasound biometry. Methods We conducted the study at the Ophthalmology Clinic, University of Malaya Medical Center, Malaysia. Phakic eyes of 76 consecutive cataract patients were measured using four different methods: IOLMaster, LENSTAR and A-scan applanation and immersion ultrasound biometry. We assessed the method agreement in the LENSTAR-IOLMaster, LENSTAR-applanation, and LENSTAR-immersion comparisons for axial length (AL) and intraocular lens (IOL) power using Bland-Altman plots. For average K, we compared LENSTAR with IOLMaster and the TOPCON KR-8100 autorefractor-keratometer. SRK/T formula was used to compute IOL power, with emmetropia as the target refractive outcome. Results For all the variables studied, LENSTAR agreement with IOLMaster is strongest, followed by those with immersion and applanation. For the LENSTAR-IOLMaster comparison, the estimated proportion of differences falling within 0.33 mm from zero AL and within 1D from zero IOL power is 100%. The estimated proportion of differences falling within 0.5 D from zero average K is almost 100% in the LENSTAR-IOLMaster comparison but 88% in the LENSTAR-TOPCON comparison. The proportion of differences falling within 0.10 mm (AL) and within 1D (IOL power) in the LENSTAR-IOLMaster comparison has practically significant discrepancy with that of LENSTAR-applanation and LENSTARimmersion comparisons. Conclusions In phakic eyes of cataract patients, measurements of AL, average K, and IOL power calculated using the SRK/T formula from LENSTAR are biometrically equivalent to those from IOLMaster, but not with those from applanation and immersion ultrasound biometry.

Preface to the second edition In the second edition of Medical Statistics from A to Z I have addedmany new definitions and taken the opportunity to correct and clarify a number of entries. More references are also provided that point readers to more detailed accounts of topics. cambridge university press

2013

Mathematical advances reached their zenith in the seventeenth century. Pierre-Simon Laplace and Pierre-Charles-Alexandre Louis, among others, advocated that probability theory and numerical procedures could be useful in all scientific disciplines, including medicine and clinical tests. However, they were opposed by most of the clinicians of the day. Prominent among the opposition was Claude Bernard, arguably the father of modern medicine, who urged doctors to reject statistics as a foundation for experimental, therapeutic and pathological science. For over a century, his disciples neglected his words almost entirely. In 1954, the British Medical Journal published "Numbering Off", the proceedings of a debate sponsored by the Royal Statistical Society on the growing application and influence of statistics in medicine. In this article, we discuss the changes in the field since the publication of the paper and the increase in mathematical sophistication and use of computers. A brief history of biostatistics is also presented. Currently, researchers depend on statistical software, which makes calculations extremely simplistic; but the increased use of computer software has resulted in the misuse of biostatistics, when data is entered into computers without understanding it and a result is generated, instead of the result. Briefly, the future is also discussed.

2009

For more than a century, attempts have been made to correlate breathing mode, craniofacial morphology ( Montgomery et al. , 1979 ; Diamond, 1980 ; Harvold et al. , 1981 ; Weber et al. , 1981 ; Hartgerink and Vig, 1989 ; Vig, 1998 ), malocclusion, and muscle function ( Linder-Aronson and Backström, 1960 ; Harvold et al. , 1981 ). It has been shown that the function of the orofacial muscles may be impaired in mouth breathers, with a short and hypotonic upper lip ( Angle, 1907 ; Ricketts, 1968 ; McNamara, 1981 ; Graber and Vanarsdall, 2000 ). However, a causal relationship determining whether craniofacial alteration is infl uenced by muscle function or muscle function by craniofacial alteration is diffi cult to establish ( Kluemper et al. , 1995 ; Vig, 1998 ). Despite this, the proponents, while advocating their point of view, do not always provide rationales on the order of the events. Gwynne-Evans (1957) believed that muscle alteration was the main causal factor leading to mouth brea...