Unusually Small F-Statistic in Analysis of Variance and Regression Analysis

2016 ◽  
Vol 3 (3) ◽  
pp. 45-59
Author(s):  
Ceyhun Ozgur
Keyword(s):  
Regression Analysis ◽  
Lower Limit ◽  
Analysis Of Variance ◽  
Control Chart ◽  
Linear Models ◽  
Statistical Significance ◽  
P Value ◽  
Mean Square ◽  
Process Change ◽  
The Mean

All textbooks and articles dealing with classical tests in the context of linear models stress the implications of a significantly large F-ratio since it indicates that the mean square for whatever effect is being evaluated contains significantly more than just error variation. In general, though, with one minor exception, all texts and articles, to the authors' knowledge, ignore the implications of an F-ratio that is significantly smaller than one would expect due to chance alone. Why this is so difficult to explain since such an occurrence is similar to a range value falling below the lower limit on a control chart for variation or a p-value falling below the lower limit on a control chart for proportion defective. In both of those cases the small value represents an unusual and significant occurrence and, if valid, a process change that indicates an improvement. Therefore, it behooves the quality manager to determine what that change is in order to have it continue. In the case of a significantly small F-ratio some problem may be indicated that requires the designer of the experiment to identify it, and to take “corrective action.” While graphical procedures are available for helping to identify some of the possible problems that are discussed they are somewhat subjective when deciding if one is looking at an actual effect; e.g., interaction, or whether the result is merely due to random variation. A significantly small F-ratio can be used to support conclusions based on the graphical procedures by providing a level of statistical significance as well as serving as a warning flag or warning that problems may exist in the design and/or analysis.

Abstract 13131: The Priority of Coronary Arteriography and Therapeutic Hypothermia After Return of Spontaneous Circulation in Patients With Out-of-hospital Cardiac Arrest. the Result of Sos-kanto 2012 Study

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Shuichi Hagiwara ◽  
Kiyohiro Oshima ◽  
Masato Murata ◽  
Makoto Aoki ◽  
Kei Hayashida ◽  
...  
Keyword(s):  
Cardiac Arrest ◽  
Therapeutic Hypothermia ◽  
Statistical Significance ◽  
Coronary Arteriography ◽  
Spontaneous Circulation ◽  
P Value ◽  
Return Of Spontaneous Circulation ◽  
Overall Performance ◽  
The Mean ◽  
Hospital Cardiac Arrest

Aim: To evaluate the priority of coronary angiography (CAG) and therapeutic hypothermia therapy (TH) after return of spontaneous circulation (ROSC) in patients with out-of-hospital cardiac arrest (OHCA). Patients and Methods: SOS-KANTO 2012 study is a prospective, multicenter (69 emergency hospitals) and observational study and includes 16,452 patients with OHCA. Among the cases with ROSC in that study, we intended for patients treated with both CAG and TH within 24 hours after arrival. Those patients were divided into two groups; patients in whom TH was firstly performed (TH group), and the others in whom CAG was firstly done (CAG group). We statistically compared the prognosis between the two groups. SPSS Statistics 22 (IBM, Tokyo, Japan) was used for the statistical analysis. Statistical significance was assumed to be present at a p value of less than 0.05. Result: 233 patients were applied in this study. There were 86 patients in the TH group (M/F: 74/12, mean age; 60.0±15.2 y/o) and 147 in the CAG group (M/F: 126/21, mean age: 63.4±11.1 y/o) respectively, and no significant differences were found in the mean age and M/F ratio between the two groups. The overall performance categories (OPC) one month after ROSC in the both groups were as follows; in the TH group, OPC1: 21 (24.4%), OPC2: 3 (3.5%), OPC3: 7 (8.1%), OPC4: 8 (9.3%), OPC5: 43 (50.0%), unknown: 4 (4.7%), and in the CAG group, OPC1: 38 (25.9%), OPC2: 13 (8.8%), OPC3: 15 (10.2%), OPC4: 18 (12.2%), OPC5: 57 (38.8%), unknown: 6 (4.1%). There were no significant differences in the prognosis one month after ROSC between the two groups. Conclusion: The results which of TH and CAG you give priority to over do not affect the prognosis in patients with OHCA.

Pie Crust Technique of the Deep Medial Collateral Ligament in Knee Arthroscopy: Ultrasound and Anatomic Study

2018 ◽  
Vol 32 (08) ◽  
pp. 764-769
Author(s):  
Guillem Claret-Garcia ◽  
Jordi Montañana-Burillo ◽  
Eduard Tornero-Dacasa ◽  
Manel Llusá-Pérez ◽  
Dragos Popescu ◽  
...  
Keyword(s):  
Medial Collateral Ligament ◽  
Statistical Significance ◽  
Mean Value ◽  
Saphenous Nerve ◽  
Medial Compartment ◽  
P Value ◽  
Collateral Ligament ◽  
Anatomical Dissection ◽  
Ultrasound Measurements ◽  
The Mean

AbstractThis article determines compartment opening of the medial articular space of the knee after pie crust (PC) technique of the medial collateral ligament (MCL) by ultrasound measurements and anatomic dissection. This is a cadaveric study of 12 specimens. Four anatomic references were marked on the skin. Distances between the femur and tibia in the internal compartment at 30 degrees of flexion were obtained with ultrasound measurements in four situations: with and without applying valgus force both prior and after the PC technique. Ultrasound measurements of the medial articular compartment were made twice and mean value was calculated. An anatomical dissection was performed and distances between the puncture marks and the infrapatellar branch of the saphenous nerve was measured. Lilliefors test of normality was applied and variables were expressed as mean and standard deviation (SD). Qualitative variables were expressed by absolute frequencies and percentages. Statistical significance was a two-tailed p-value of < 0.05. Prior to the PC technique, mean (SD) distance between the femur and tibia in the medial compartment were 14.2 (4.0) mm in basal conditions and 17.1 (3.7) mm when applying valgus force (p = 0.003). PC technique increased the mean (SD) distance by 1.9 (1.9) mm under basal conditions (p < 0.01) and 2.9 (1.6) mm when applying valgus force (p < 0.01). The infrapatellar branches of the saphenous nerve were not damaged and the mean (SD) distance between the punctures and the nerve was 9.0 (3.3) mm. The PC is a reproducible, safe, and measurable surgical technique that opens controllably the medial compartment. PC as described avoided damage to the nerve branches.

scholarly journals Unravelling the mystery of the ‘minimum important difference’ using practical outcome measures in chronic respiratory disease

2019 ◽  
Vol 16 ◽  
pp. 147997311881649 ◽  
Author(s):  
Linzy Houchen-Wolloff ◽  
Rachael A Evans
Keyword(s):  
Outcome Measures ◽  
Outcome Measure ◽  
Statistical Significance ◽  
Minimum Clinically Important Difference ◽  
Chronic Respiratory Disease ◽  
Important Change ◽  
P Value ◽  
Minimum Important Difference ◽  
The Mean ◽  
Functional Outcome Measures

It is important for clinicians and researchers to understand the effects of treatments on their patients, both at an individual and group level. In clinical studies, treatment effects are often reported as a change in the outcome measure supported by a measure of variability; for example, the mean change with 95% confidence intervals and a probability ( p) value to indicate the level of statistical significance. However, a statistically significant change may not indicate a clinically meaningful or important change for clinicians or patients to interpret. The minimum clinically important difference (MCID) or minimally important difference (MID) has therefore been developed to add clinical relevance or patient experience to the reporting of an outcome measure. In this article, we consider the concept of the MID using the example of practical outcome measures in patients with CRD. We describe the various ways in which an MID can be calculated via anchor- and distribution-based methods, looking at practical examples and considering the importance of understanding how an MID was derived when seeking to apply it to a particular situation. The terms MID and MCID are challenging and often used interchangeably. However, we propose all MIDs are described as such, but they could be qualified by a suffix: MIDS (MID – Statistical), MID-C (MID – Clinical outcome), MID-P (MID – Patient determined). However, this type of classification would only work if accepted and adopted. In the meantime, we advise clinicians and researchers to use an MID where possible to aid their interpretation of functional outcome measures and effects of interventions, to add meaning above statistical significance alone.

scholarly journals Bereitschaftspotential preceding eyelid blinks in Parkinson’s disease

2017 ◽  
Vol 75 (8) ◽  
pp. 539-545
Author(s):  
Isabella Araújo Mota ◽  
Maria das Graças Coriolano ◽  
Otávio Gomes Lins
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Analysis Of Variance ◽  
Statistical Significance ◽  
Healthy Controls ◽  
Negative Wave ◽  
The Mean ◽  
Normal Controls

ABSTRACT The Bereitschaftspotential (BP) is a negative wave observed in EEG retrograde averaging, preceding a motor act. The objective was to study the BP preceding voluntary eyelid blinks in Parkinson’s disease (PD) patients during off and on phases of levodopa. Methods Ten PD patients in stages 1 and 2 of the Hoehn & Yahr classification were compared to 18 healthy controls. Artifact-free EEG segments of two seconds preceding the onset of the blink potential were averaged and analyzed, and the statistical significance of the measured amplitudes were evaluated by analysis of variance models. Results The presence of a BP in the PD patients was demonstrated. The mean amplitudes at 0 ms were respectively 0.6 µV and 3.3 µV for the BP patients and the normal controls, respectively. Conclusions The BP amplitudes were significantly smaller in PD patients than normal participants. The amplitudes of the BP were not modified by levodopa.

scholarly journals The behavior of Mean Platelet Volume in Sepsis in critical patients with and without sepsis

Bionatura ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 1812-1817
Author(s):  
Pablo Andrés Vélez ◽  
Lucy Baldeón R ◽  
Jorge Luis Vélez-Paez
Keyword(s):  
Mean Platelet Volume ◽  
Statistical Significance ◽  
Area Under The Curve ◽  
Biological Behavior ◽  
P Value ◽  
Platelet Volume ◽  
Significant Area ◽  
The Mean ◽  
Critical Patients ◽  
Elevated Lactate

The mean platelet volume is an anatomical biomarker that has shown its usefulness in various cardiovascular and metabolic pathologies; in sepsis, it has been positioning itself as an indicator of mortality, easily accessible and immediately applicable when reported in the routine blood count. This study demonstrates the mean platelet volume's biological behavior in critical patients with sepsis compared with non-septic patients. An observational, longitudinal, prospective, monocentric cohort study was conducted in 250 patients treated at the intensive care unit of the Pablo Arturo Suárez Hospital, Quito- Ecuador, from January 2019 January 2020. A group of patients with sepsis (n = 125) and without infectious pathologies (n = 125) were studied. The inclusion criteria were patients over 18 years of age of both genders, diagnosed with sepsis or septic shock using SEPSIS 3 criteria, and patients without septic pathology. The mean platelet volume (MPV) of days 1, 2, and 3 were studied. Septic patients had a mean APACHE (18.74 SD 9.52) higher than the non-septic ones (11.93 SD 7.01) (p = < 0.000). The MPV was consistently higher in patients with sepsis than non-septic patients, but it reached statistical significance on day 3 (9.13 SD 1.55 vs. 8.66 SD 1.34, p=0.042). The MPV on day 3 presented a significant area under the curve (AUC =0.580) (CI. 0.500-0.661), where the cut-off point according to Youden's index was positive for sepsis if MPV≥ 9.85 femtoliter (fL) with OR=3.30 and p-value= 0.005. Likewise, lactate on admission showed an AUC of 0.625 (CI. 0.555-0.694), with a cut-off point ≥of 1.15 mmol / L, OR=2.51, and p=0.007. Age and hypertension did not show a multivariate relationship with the presence of sepsis. It was shown that MPV is higher in patients with sepsis compared to non-septic ones. This observation reaches significance on day 3. Additionally, elevated lactate at admission was also associated with a septic state. On the other hand, platelet count did not show the expected behavior.

scholarly journals Job Satisfaction among Hemodialysis and Labour Ward Nurses: A Comparative Descriptive Study

2021 ◽  
pp. 48-56
Author(s):  
Monisayo Olayemi Komolafe
Keyword(s):  
Job Satisfaction ◽  
Work Environment ◽  
Statistical Significance ◽  
Descriptive Study ◽  
P Value ◽  
Satisfaction Scale ◽  
Cross Sectional ◽  
Dialysis Unit ◽  
The Mean ◽  
Labour Ward

Introduction: Increasing CKD cases means higher demands for haemodialysis nurses. Haemodialysis nurses are required to fulfil many demanding roles such as advocate, caregiver, educator, mentor and technician while patients attend a dialysis unit. The complexities of the role that are performed by these nurses along with organization factors within the work environment have led to haemodialysis nurses experiencing high levels of burnout thus impacting on satisfaction derived from job done. Objectives: To compare job satisfaction among haemodialysis nurses with that of labour ward nurses and determine if the type of patient managed affects job satisfaction of nurses. Methodology: The multidimensional Job satisfaction scale designed and validated by Murat Ozpehlivan and Zafer Acar was used to determine job satisfaction among sixty-six hemodialysis nurses and sixty-four labour ward nurses in a cross sectional comparative descriptive study. Statistical significance difference between the two group of nurses attributed to events with a p-value lower than 5% (p < 0.05). Results: The overall mean job satisfaction score was higher among the labour ward nurses 67.95 ± 13.39 compared to the mean score among renal nurses 65.07 ± 14.24 (T= 1.81, p = 0.240). The mean score of labour ward nurses regarding satisfaction based on patient managed 74.51 ± 14.96 is higher than the mean score among renal participants of 71.21 ± 14.70 (T= 1.27, p = 0.201). Conclusion: Hemodialysis nurses in Nigeria are satisfied with the job they do and this is comparable to that of nurses in labour ward.

227 CALRETICULIN, A 60-kDa PROTEIN, PREVENTS POLYSPERMY IN ZONA PELLUCIDA-FREE PIG OCYTES

2013 ◽  
Vol 25 (1) ◽  
pp. 261
Author(s):  
R. Romar ◽  
C. Soriano-Úbeda ◽  
M. D. Saavedra ◽  
J. Gadea ◽  
M. Avilés ◽  
...  
Keyword(s):  
Zona Pellucida ◽  
Calcium Binding ◽  
Statistical Significance ◽  
P Value ◽  
Oocyte Activation ◽  
Cortical Granules ◽  
Chaperone Protein ◽  
The Mean

After gamete membrane fusion or artificial oocyte activation, cortical granules undergo exocytosis and the released content modifies the zona pellucida (ZP), preventing polyspermy. Calreticulin (CRT), a calcium-binding highly conserved protein of 60 kDa, is contained in cortical granules from hamster eggs (Muñoz-Gotera et al. 2001 Mol. Reprod. Dev. 60), and we recently showed it is exocytosed from chemically activated ZP-free pig oocytes (Romar et al. 2012 Reprod. Fertil. Dev. 24). When pig ZP-enclosed oocytes were incubated with CRT, monospermy was not improved (Romar et al. 2011, Maternal communication with gametes and embryo, p. 72), suggesting that the likely role of CRT in preventing polyspermy might be carried out at the oolemma level. Our objective was to evaluate whether CRT prevents polyspermy in pig ZP-free oocytes by treating the cells with this protein before being inseminated. In vitro-matured cumulus–oocyte complexes (44 h, NCSU-37 medium) were decumulated and ZP was digested with Tyrode’s acid. The ZP-free oocytes were incubated for 30 min in TALP medium supplemented with 0, 100, 1000, and 5000 pg of CRT (ab91577, Abcam, Cambridge, MA, USA) per oocyte. After washing, ZP-free oocytes were inseminated (25 000 sperm mL–1) and gametes were co-cultured for 18 h. Putative zygotes were fixed and stained with Hoechst 33342 to analyse the fertilization results. Four replicates with 30 to 35 oocytes per group were done, and results were analysed by one-way ANOVA. A P-value ≤0.05 was taken to denote statistical significance. Incubation with CRT did not affect penetration rates that were similar among groups (77.12 ± 3.88 and 72.73 ± 4.07, respectively, for the 0- and 5000-pg CRT groups). However, the mean number of sperm per penetrated oocyte decreased from 3.01 ± 0.28 (0-pg group) to 2.07 ± 0.16 (5000-pg group), and monospermy rate increased from 30.77 ± 4.87 (0-pg group) to 52.27 ± 5.36 (5000-pg group; P ≤ 0.05). Incubation with CRT did not affect the number of sperm attached to oolemma, which was similar among all groups (11.45 ± 1.16 v. 10.75 ± 1.17, respectively, for 0 and 5000 pg of CRT). These preliminary data suggest that CRT, a protein exocytosed after oocyte activation, participates in the membrane block to polyspermy in pigs. Future studies to describe the exact mechanism of action of this chaperone protein are necessary. Supported by MEC and FEDER (AGL2009-12512-C02-01).

Activation of Clotting Factors in Thrombocytopenia Due to Platelets Destruction: A Possible Compensated Mechanism for Hemostasis.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3999-3999
Author(s):  
Vincenzo Fontana ◽  
Wenche Jy ◽  
Eugene Ahn ◽  
Pamela Dudkiewicz ◽  
Lawrence L. Horstman ◽  
...  
Keyword(s):  
Bone Marrow Failure ◽  
Statistical Significance ◽  
Mean Value ◽  
P Value ◽  
Clotting Factors ◽  
Platelet Destruction ◽  
Excessive Bleeding ◽  
Giant Platelets ◽  
Fatal Bleeding ◽  
The Mean

Abstract INTRODUCTION. Thrombocytopenia (TP) due to bone marrow failure, as in aplastic anemia (AA), is often associated with frequent and fatal bleeding, whereas fatal bleeding in TP due to platelet destruction, as in ITP, is rare. It has been suggested that giant platelets or increased cell-derived microparticles (MP) act to limit bleeding in ITP. We investigated clotting factors and MP from 3 cell types, platelets (PMP), leukocytes (LMP), and endothelial (EMP), in patients with different causes of their TP. METHODS. Group 1 (platelet destruction) consisted of 2 subgroups, Grp 1a having n=35 pts with active ITP (ITP-A) and Grp 1b having n=15 pts with platelet destruction (PD) by other disorders (TTP, PNH, others). Group 2 (impaired production (IP)) consisted of n=19 pts with AA, MDS/MPD, and others. Group 3 comprised n=28 pts with ITP in remission (ITP-R). Laboratory measures included CBC, platelets, FVIII, FIX, FXI, and 3 kinds of MP: PMP, LMP, EMP. Signs and symptoms of bleeding were graded and recorded. RESULTS. Key data is summarized in Table 1. The percentage of patients with elevated activity of FVIII was significantly more prevalent in Grp 1a vs. Grp 3 (53% vs. 15%, p=0.002) or Grp 1b vs. Grp 2 (73% vs. 11%, p=0.0002). The mean value of FVIII titer was also significantly higher in Grp 1a vs. Grp 3 (1.92 vs. 1.33 U/mL, p=0.0036) or Grp 1b vs. Grp 2 (2.44 vs. 1.18 U/mL, p=0.00007). The mean percentage of patients with elevated FIX or FXI, or the mean value of FIX or FXI titer were also higher in Grp 1a vs. Grp 3 or Grp 1b vs. Grp 2, but the difference did not reach statistical significance. PMP counts were found to correlate with platelet counts in all groups, and were significantly higher in Grp 3 than Grp 1a (p=0.0004). Grp 3 also had higher EMP than Grp 1a (p=0.04). LMP showed no significant differences. REPRESENTATIVE CASE. A patient with chronic ITP who relapsed with severe acute ITP was monitored sequentially. In acute phase of TP, activities of FVIII, FIX, and FXI surged, in parallel with shortening of aPTT, and patient had minimal signs of bleeding. Serial assays revealed gradual fall of factor activities, reaching normal levels after 5 months. A similar pattern was observed in another patient, with acute TTP: clotting factors returned to normal after 2 months. CONCLUSION. TP due to platelet destruction appears to trigger activation of intrinsic clotting pathway which may protect from excessive bleeding. Surge in FVIII was most notable. This compensation effect appears to be absent in TP due to depressed platelet production, and likewise for ITP in remission. The mechanism underlying this phenomenon remains to be elucidated. Further study is in progress to delineate the mechanism. Table 1 Grp1a (ITP-A) Grp1b (PD) Grp2 (IP) Grp3 (ITP-R) p value p value Number 35 15 19 28 1a vs 3 1b vs 2 FVIII (%) 53 73 11 15 0.002 0.0002 FIX (%) 19 27 6 13 NS NS FXI (%) 16 14 0 8 NS NS PMP 8315 15531 9768 17085 0.0004 NS EMP 328 325 393 578 0.04 NS LMP 1388 1230 1255 1486 NS NS

Profile of Cell-Derived Microparticles (C-MP) in ITP: Red Cell Microparticles (RMP) Correlate with Severity of ITP.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1087-1087
Author(s):  
Vincenzo Fontana ◽  
Pamela Dudkiewicz ◽  
Eugene Ahn ◽  
Wenche Jy ◽  
Lawrence L. Horstman ◽  
...  
Keyword(s):  
Statistical Significance ◽  
Annexin V ◽  
Inverse Correlation ◽  
Intravenous Immunoglobulins ◽  
Mean Value ◽  
P Value ◽  
Clotting Factors ◽  
Anionic Phospholipids ◽  
The Mean ◽  
Sensitive Marker

Abstract BACKGROUND: The roles of cell-derived microparticles (C-MP) released from platelets (PMP), endothelial cells (EMP), leukocytes (LMP) and red cells (RMP) in hemostasis, thrombosis and inflammation have been appreciated in recent years. Although PMP were shown to be hemostatically active, the roles of other C-MP, especially RMP, have not been studied in ITP. We investigated C-MP in patients with ITP. MATERIAL AND METHODS: One-hundred-six patients with ITP were studied. They consisted of 73 pts with active ITP (ITP-A, 30M/43F, mean age 53.8 yr) and 33 pts in remission (ITP-R, 4M/29F, mean age 53.4 yr). ITP-A was defined by plt count &lt;140,000 for &gt;3 months; ITP-R was defined by plt count &gt;140,000 for &gt;3 months. Mean plt counts was 78,000 for ITP-A and 224,000 for ITP-R. The two groups were similar in ages. CBC with plt count, aPTT and activities of FVIII, FIX, FXI, were measured. Using flow cytometry, PMP were identified by CD41+, EMP by CD31+/CD41−, LMP by CD45+, and RMP by glycophorin+. Effects of intravenous immunoglobulins (IVIG) on C-MP were also evaluated. RESULTS: There was a strong inverse correlation between plt counts and RMP (p=0.002). RMP were higher when plt counts were lower. A significant correlation was found between platelet counts and PMP (p&lt;0.0001) and EMP (p&lt;0.0001), but not LMP (p&gt;0.05). The mean value of RMP was higher in ITP-A than ITP-R (p= 0.009). Conversely, PMP and EMP were higher in ITP-R (P&lt;0.0001). No difference was found in LMP. FVIII and IX were higher in ITP-A than ITP-R (p=0.006, p=0.001, respectively).The aPTT was shorter and FXI higher in ITP-A but they did not reach statistical significance. Only RMP (not PMP, EMP or LMP) correlated with elevated factors VIII, IX and XI (P=0.005, 0.001 and 0.005 respectively) and inversely correlated with aPTT (p=0.009). Infusion of IVIG reduced RMP (RMP pre/post=1519/1018), not the other C-MP, in 9 pts DISCUSSION/CONCLUSIONS: (i) RMP inversely correlated with plt counts and appear to be a sensitive marker of severity of ITP. However mechanisms of RMP generation, their reduction following IVIG and their roles remain to be elucidated. (ii) Among C-MP, only RMP, not other C-MP, were associated with shortening aPTT and elevated FVIII, IX, XI. (iii) RMP are positive for annexin V, providing anionic phospholipids for clotting factors and generating thrombin (data not shown). These findings suggest that RMP associated with these factors are involved in hemostasis to prevent bleeding in severe ITP. Table 1. ITP-A ITP-R p-value No. Patients 73 33 Plt count 78,000 224,000 &lt;0.0001 C-MP: PMP 8074 16403 &lt;0.0001 EMP 292 667 &lt;0.0001 LMP 1718 1705 n. s. RMP 2292 1505 &lt;0.01 Coag: aPTT 24.9 25.7 n. s. FVIII 1.95 1.50 0.006 FIX 1.53 1.28 0.001 FXI 1.29 1.12 n.s.

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