Why P values are not measures of evidence

Summary Objective: To determine the intravascular electrolyte status in dairy cows with respect to age and different courses of parturition to clarify etiological factors influencing peri- or intrapartal imbalances of electrolyte homeostasis. Material and methods: A total of 64 cows at birth were evaluated (primiparous n = 34, pluriparous n = 30). Thirty-three cows showed normal delivery, while 31 cows had a complicated birth. Blood samples were collected intra partum (i. p.) and 2, 4, 6, 8, 12, 16, 24 h post partum (p. p.) as well as [2, 3, 4, 5, 7, 10 days p. p. and levels of total calcium (Catotal), ionized calcium (Caion), inorganic phosphate (Pa), Mg, Na, K, Cl were determined. Results: The results revealed that electrolytes show great fluctuation during and immediately p. p. in relation to age. Already during parturition pluriparous cows had a lower Catotal and Pa concentration compared to primiparous animals. Cows with dystocia exhibited a more intensive and longer lasting decrease of Ca compared to cows with normal birth. In relation to age and severity of birth Pa concentration showed a differing but basically typical course for this electrolyte. Mg, Na, K and Cl concentrations were higher during and immediately after birth compared to p. p. values. Until day 10 p. p. these electrolyte concentrations declined more in older cows with dystocia compared to younger animals. However, the influence of dystocia on concentration of these electrolytes was milder in contrast to Ca and Pa. Conclusions: In summary, primarily older cows are predisposed to imbalances of electrolyte homeostasis intra partum and at the beginning of the lactation. These changes are potentiated in case of complications during parturition. Intravascular Catotal, Caion as well as Pa are most severely affected. Clinical relevance: These results may constitute the basis for a comprehensive metaphylaxis during the peripartal period, especially in cows after dystocia, to positively influence the early convalescence phase.

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Values, beliefs, and attitudes technical guide for Forest Service land and resource management, planning, and decision-making

10.2737/pnw-gtr-788 ◽

2009 ◽

Cited By ~ 8

Author(s):

Stewart D. Allen ◽

Denise A. Wickwar ◽

Fred P. Clark ◽

Robert R. Dow ◽

Robert Potts ◽

...

Keyword(s):

Decision Making ◽

Resource Management ◽

Forest Service ◽

Management Planning ◽

P Values ◽

Technical Guide ◽

Resource Management Planning ◽

Beliefs And Attitudes

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STEM Education Problem Through Striking Differences Between Physics and Biology

10.31219/osf.io/4kydt ◽

2019 ◽

Author(s):

Adib Rifqi Setiawan

Keyword(s):

Nature Of Science ◽

Stem Education ◽

Functional Relationship ◽

Theoretical Models ◽

Natural Sciences ◽

Physical Sciences ◽

P Values ◽

The Third ◽

Differences Of Opinion ◽

Biological Education

This work argues that fundamental differences of opinion as to the nature of science affect whether the “S” in STEM can really apply to all the natural sciences, which will affect how we structure and implement improvements in STEM education. The first part of the argument deals with often-taught definitions of words like “law” and “theory” that don’t really apply to much of physics. In the second part, we notes that mathematics remains inseparable from education in the physical sciences, but this is not the case in biology. Moreover, an appreciation for the worth of mathematical or theoretical models, even disjoint from experiments, is not generally a part of biological education. The third part is “the tyranny of hypotheses.” One of the “cultural” shocks I’ve had moving into biological fields is constantly hearing people talk about “hypotheses” and seeing a steady stream of bar graphs with asterisks and p-values. In physics, one almost never discusses hypotheses; rather, one test relationships between parameters, either analyzing them within some mechanistic framework, or empirically determining what the underlying functional relationship is.

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Editorial. When can we be positive about p values?

Journal of Neurosurgery ◽

10.3171/2018.10.jns182494 ◽

2020 ◽

Vol 132 (2) ◽

pp. 656-661

Author(s):

Michael Glantz ◽

Nicholas Brandmeir

Keyword(s):

P Values

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Reporting trends of p values in the neurosurgical literature

Journal of Neurosurgery ◽

10.3171/2018.8.jns172897 ◽

2020 ◽

Vol 132 (2) ◽

pp. 662-670

Author(s):

Minh-Son To ◽

Alistair Jukes

Keyword(s):

Text Mining ◽

Publication Bias ◽

Temporal Trends ◽

P Values ◽

Significance Threshold

OBJECTIVEThe objective of this study was to evaluate the trends in reporting of p values in the neurosurgical literature from 1990 through 2017.METHODSAll abstracts from the Journal of Neurology, Neurosurgery, and Psychiatry (JNNP), Journal of Neurosurgery (JNS) collection (including Journal of Neurosurgery: Spine and Journal of Neurosurgery: Pediatrics), Neurosurgery (NS), and Journal of Neurotrauma (JNT) available on PubMed from 1990 through 2017 were retrieved. Automated text mining was performed to extract p values from relevant abstracts. Extracted p values were analyzed for temporal trends and characteristics.RESULTSThe search yielded 47,889 relevant abstracts. A total of 34,324 p values were detected in 11,171 abstracts. Since 1990 there has been a steady, proportionate increase in the number of abstracts containing p values. There were average absolute year-on-year increases of 1.2% (95% CI 1.1%–1.3%; p < 0.001), 0.93% (95% CI 0.75%–1.1%; p < 0.001), 0.70% (95% CI 0.57%–0.83%; p < 0.001), and 0.35% (95% CI 0.095%–0.60%; p = 0.0091) of abstracts reporting p values in JNNP, JNS, NS, and JNT, respectively. There have also been average year-on-year increases of 0.045 (95% CI 0.031–0.059; p < 0.001), 0.052 (95% CI 0.037–0.066; p < 0.001), 0.042 (95% CI 0.030–0.054; p < 0.001), and 0.041 (95% CI 0.026–0.056; p < 0.001) p values reported per abstract for these respective journals. The distribution of p values showed a positive skew and strong clustering of values at rounded decimals (i.e., 0.01, 0.02, etc.). Between 83.2% and 89.8% of all reported p values were at or below the “significance” threshold of 0.05 (i.e., p ≤ 0.05).CONCLUSIONSTrends in reporting of p values and the distribution of p values suggest publication bias remains in the neurosurgical literature.

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Assessing variability in surgical decision making among attending neurosurgeons at an academic center

Journal of Neurosurgery ◽

10.3171/2019.2.jns182658 ◽

2020 ◽

Vol 132 (6) ◽

pp. 1970-1976

Author(s):

Ashwin G. Ramayya ◽

H. Isaac Chen ◽

Paul J. Marcotte ◽

Steven Brem ◽

Eric L. Zager ◽

...

Keyword(s):

Spine Surgery ◽

Repeated Measures ◽

Elective Surgery ◽

Statistical Tests ◽

Neurosurgical Procedures ◽

P Values ◽

Surgical Interventions ◽

Radiology Reports ◽

Operative Notes ◽

First Time

OBJECTIVEAlthough it is known that intersurgeon variability in offering elective surgery can have major consequences for patient morbidity and healthcare spending, data addressing variability within neurosurgery are scarce. The authors performed a prospective peer review study of randomly selected neurosurgery cases in order to assess the extent of consensus regarding the decision to offer elective surgery among attending neurosurgeons across one large academic institution.METHODSAll consecutive patients who had undergone standard inpatient surgical interventions of 1 of 4 types (craniotomy for tumor [CFT], nonacute redo CFT, first-time spine surgery with/without instrumentation, and nonacute redo spine surgery with/without instrumentation) during the period 2015–2017 were retrospectively enrolled (n = 9156 patient surgeries, n = 80 randomly selected individual cases, n = 20 index cases of each type randomly selected for review). The selected cases were scored by attending neurosurgeons using a need for surgery (NFS) score based on clinical data (patient demographics, preoperative notes, radiology reports, and operative notes; n = 616 independent case reviews). Attending neurosurgeon reviewers were blinded as to performing provider and surgical outcome. Aggregate NFS scores across various categories were measured. The authors employed a repeated-measures mixed ANOVA model with autoregressive variance structure to compute omnibus statistical tests across the various surgery types. Interrater reliability (IRR) was measured using Cohen’s kappa based on binary NFS scores.RESULTSOverall, the authors found that most of the neurosurgical procedures studied were rated as “indicated” by blinded attending neurosurgeons (mean NFS = 88.3, all p values < 0.001) with greater agreement among neurosurgeon raters than expected by chance (IRR = 81.78%, p = 0.016). Redo surgery had lower NFS scores and IRR scores than first-time surgery, both for craniotomy and spine surgery (ANOVA, all p values < 0.01). Spine surgeries with fusion had lower NFS scores than spine surgeries without fusion procedures (p < 0.01).CONCLUSIONSThere was general agreement among neurosurgeons in terms of indication for surgery; however, revision surgery of all types and spine surgery with fusion procedures had the lowest amount of decision consensus. These results should guide efforts aimed at reducing unnecessary variability in surgical practice with the goal of effective allocation of healthcare resources to advance the value paradigm in neurosurgery.

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