Why we habitually engage in null-hypothesis significance testing:A qualitative study

BACKGROUND: Null Hypothesis Significance Testing (NHST) is the most familiar statistical procedure for making inferences about population effects. Important problems associated with this method have been addressed and various alternatives that overcome these problems have been developed. Despite its many well-documented drawbacks, NHST remains the prevailing method for drawing conclusions from data. Reasons for this have been insufficiently investigated. Therefore, the aim of our study was to explore the perceived barriers and facilitators related to the use of NHST and alternative statistical procedures among relevant stakeholders in the scientific system. METHODS: Individual semi-structured interviews and focus groups were conducted with junior and senior researchers, lecturers in statistics, editors of scientific journals and program leaders of funding agencies. During the focus groups, important themes that emerged from the interviews were discussed. Data analysis was performed using the constant comparison method, allowing emerging (sub)themes to be fully explored. A theory substantiating the prevailing use of NHST was developed based on the main themes and subthemes we identified. RESULTS: Twenty-nine interviews and six focus groups were conducted. Several interrelated facilitators and barriers associated with the use of NHST and alternative statistical procedures were identified. These factors were subsumed under three main themes: the scientific climate, scientific duty, and reactivity. As a result of the factors, most participants feel dependent in their actions upon others, have become reactive, and await action and initiatives from others. This may explain why NHST is still the standard and ubiquitously used by almost everyone involved. CONCLUSION: Our findings demonstrate how perceived barriers to shift away from NHST set a high threshold for actual behavioral change and create a circle of interdependency between stakeholders. By taking small steps it should be possible to decrease the scientific community’s strong dependence on NHST and p-values

BMI and HbA1c are metabolic markers for pancreatic cancer: matched case-control study using a UK primary care database

Background Weight loss, hyperglycaemia and diabetes are known features of pancreatic cancer. We quantified the timing and the amount of changes in body mass index (BMI) and glycated haemoglobin (HbA1c), and their association with pancreatic cancer from five years before diagnosis. Methods A matched case-control study was undertaken within 590 primary care practices in England, United Kingdom. 8,777 patients diagnosed with pancreatic cancer (cases) between 1st January 2007 and 31st August 2020 were matched to 34,979 controls by age, gender and diabetes. Longitudinal trends in BMI and HbA1c were visualised. Odds ratios adjusted for demographic and lifestyle factors (aOR) and 95% confidence intervals (CI) were calculated with conditional logistic regression. Subgroup analyses were undertaken according to the diabetes status. Results Changes in BMI and HbA1c observed for cases on longitudinal plots started one and two years (respectively) before diagnosis. In the year before diagnosis, a 1 kg/m2 decrease in BMI between cases and controls was associated with aOR for pancreatic cancer of 1.05 (95% CI 1.05 to 1.06), and a 1 mmol/mol increase in HbA1c was associated with aOR of 1.06 (1.06 to 1.07). ORs remained statistically significant (p < 0.001) for 2 years before pancreatic cancer diagnosis for BMI and 3 years for HbA1c. Subgroup analysis revealed that the decrease in BMI was associated with a higher pancreatic cancer risk for people with diabetes than for people without (aORs 1.08, 1.06 to 1.09 versus 1.04, 1.03 to 1.05), but the increase in HbA1c was associated with a higher risk for people without diabetes than for people with diabetes (aORs 1.09, 1.07 to 1.11 versus 1.04, 1.03 to 1.04). Conclusions The statistically significant changes in weight and glycaemic control started three years before pancreatic cancer diagnosis but varied according to the diabetes status. The information from this study could be used to detect pancreatic cancer earlier than is currently achieved. However, regular BMI and HbA1c measurements are required to facilitate future research and implementation in clinical practice

The validity of arthroscopic simulators and performance tools

As there is a growing demand for more time-efficient and effective methods for medical training without putting patients at risk, the role of simulation keeps expanding. Validation of simulators should precede implementation in medical curricula. However, only a small minority of available medical simulators is found to be (appropriately) validated. Researchers, manufacturers and medical trainers are therefore encouraged to collaborate to develop simulators, conduct proper validation studies and select the appropriate simulator. Especially in the field of arthroscopy, a lack of (properly validated) simulators exists. Two high-fidelity arthroscopic knee simulators are studied for face and construct validity, and a pilot study is conducted to develop a solid protocol for a large scale randomized controlled transfer validity study. The acquirement of arthroscopic skills is stimulated by the use of objective tools and metrics to monitor arthroscopic performance and provide feedback. As metrics and complementary thresholds for safety performance during arthroscopy are scarcely studied, maximum allowed forces for safe joint stressing are investigated. Moreover, construct validity of two Global Rating Scales, designed for evaluation of arthroscopic performance is studied. Although the number of (high-fidelity) arthroscopic simulators and performance tracking tools have recently increased, more evidence on their validity and usefulness of simulators and assessment tools is needed. Future studies should focus on high-quality study designs and standardized protocols in order to offer orthopedic residents an adequate training environment to acquire and maintain arthroscopic skills, and to enable performance tracking and proficiency assessment, with the ultimate goal to improve and secure patient safety

Letter dated 30 June 1969 from A. V. Stunt to Lorenzo A. Richards

Letter dated 30 June 1969 from A. V. Stunt at the Editorial Office of Earth-Science Reviews/Atlas (International Magazine for Geo-Scientists) to Lorenzo A. Richards, asking if he would review a textbook; Includes his hand-written reply that "my time is obligated for the next while" and suggesting another nameEARTH-SCIENCE REVIEWS/ATLAS International Magazine for Geo-Scientists with News Supplement Atlas EDITORIAL OFFICE RO. Box 1345 AMSTERDAM ~C The Netherlands Dr. L.A. Richards c/'o Regional Salinity Laboratory U.S. Department of Agriculture Riverside, Calif. U.S.A. Our ref. TD Your ref. AMSTERDAM, June 305 1969 Dear Dr. Richards: We have been informed by Prof. J.P. Quirk (University of Wes­tern Australias Nedlands) that you might be prepared to write a review of about 600-800 words on the following publications E.G. Childs; An Introduction to the Physical Basis of Soil Water Phenomena. John Wiley & Sons Ltd., London-New York-Sydney-Toronto, 1969, 493 PP«5 120s. If you are willing to prepare this review, a free copy of the book will be sent to you. In case you are not in the position to comply with our request we would be grateful if you could send us the names of some of your colleagues who might be interested in writing this article. Awaiting the oleasure of your renlv, jwitf, IMTIM A**%AS *? Atyyufa/iy QOAYiTL^rUA^ , JjtTrf.iy $*</ Scl. sOCvtTiJ . */ UrTt^CyVtytyiy^, /ft***£<4U+T» t ^«^*<^v***^ ODjOC (signed in his absence by A /7? * Miss C. van Dam, secretary) 1 013.1 mcere. HDITOHIAL OFFICE ]ARTH-SCIEUCE IiSVIEWS/ATLAS A.Y. Stun- PUBLISHERS: ELSEVIER PUBLISHING COM PAN Y - AM STE RD A

The role of the cytoplasmic domain in the localisation of CTLA-4 and CD28

SIGLEAvailable from British Library Document Supply Centre- DSC:DXN065419 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

NHST project

The file contains the results of the search conference that was part and an aim of the project 'The Myth of Null-hypothesis Significance Testing