scholarly journals Electronic cigarettes

2016 ◽  
Author(s):  
Jackie Sham ◽  
BCIT School of Health Sciences, Environmental Health ◽  
Vanessa Karakilic ◽  
Kevin Soulsbury ◽  
Fred Shaw
Keyword(s):  
Null Hypothesis ◽  
Electronic Cigarettes ◽  
Statistical Significance ◽  
Electronic Cigarette ◽  
Health Concern ◽  
Inferential Statistics ◽  
P Values ◽  
Nicotine Content ◽  
Nicotine Concentration ◽  
Significant Difference

  Background and Purpose: Electronic cigarettes are gaining vast popularity because the perceived impression about electronic cigarettes is they are a safer alternative to conventional smoking (Belluz, 2015). As a result, more teenagers are switching to electronic cigarettes either as a smoking cessation tool, or for recreational use. However, it is supported by the evidence review that there is nicotine mislabeling between what the manufacturer has labeled and the actual nicotine content in the liquids (Goniewicz et al., 2012). This is a critical health concern for teenagers and recreational users because they are exposed to nicotine, which is a neurotoxin that creates the addiction for smoking. As a result, over a period of time, recreational electronic cigarette users have a higher chance of switching to conventional smoking (Bach, 2015). Hence, the purpose of this research is to determine whether nicotine can be found in nicotine free electronic cigarette liquids Methods: The nicotine content in the electronic cigarette liquids will be determined using Gas Chromatography - Mass Spectrometry. Inferential statistics such as a one tailed t-test will be done using Microsoft Excel and SAS to see if nicotine can be detected in nicotine-free electronic cigarette liquids and if there is a statistically significant difference. Results: The two p-values from the parametric test were 0.2811 and 0.2953. The p-value to reject the null hypothesis was set at 0.05. Because the p-values from the inferential statistics were greater than 0.05, the null hypothesis was not rejected and the actual nicotine content is equal to what the manufacturer had labeled as nicotine free. Discussion: Although the inferential statistics indicated that there was no statistical significance in nicotine concentration, two out of the ten nicotine free electronic cigarette liquids measured nicotine levels above 0 ppm. Conclusion: There was not a significant difference in nicotine concentration found in the electronic cigarette liquids and the actual nicotine concentration is equal to the labeled concentration. However, because the sample size of only ten is too small, there is a potential for type 2 error. Also, the samples came from only two manufacturers. Therefore, the results from this research are not representative for all the electronic cigarette liquids. More research should be conducted to provide scientific evidence to stop recreational electronic cigarette users from the exposure of electronic cigarettes as these could act as a stepping-stone towards smoking conventional cigarettes. Teenagers who start smoking at an early age will be more  

scholarly journals Presence of nicotine in marketed nicotine-free e-liquids for electronic cigarettes

2017 ◽  
Author(s):  
Michael Wu ◽  
BCIT School of Health Sciences, Environmental Health ◽  
Helen Heacock ◽  
Maria Tirado ◽  
Fred Shaw
Keyword(s):  
Public Perception ◽  
Electronic Cigarettes ◽  
Electronic Cigarette ◽  
Gas Chromatography Mass Spectrometry ◽  
Nicotine Content ◽  
Active Chemical ◽  
Significant Difference ◽  
Degree Of Confidence ◽  
Susceptible Populations ◽  
High Degree

  Background and Purpose: Ever since the electronic cigarette made its debut in the market, it has been garnering great popularity due to public perception of it being a safer alternative to conventional cigarette. As a result, aside from being utilized in tobacco cessation programs, susceptible populations such as teenagers are slowly adopting this new trend of recreational E-cigarette smoking or “vaping”. The literature review conducted suggests that not only do different E-cigarette models exhibit different delivery efficiencies regarding percentage nicotine vapourization, there are discrepancies between what is labelled by the manufacturer and the actual nicotine content in the electronic cigarette liquids. This has serious public health implications because nicotine is the active chemical component in inducing addiction in cigarettes. As a result, recreational electronic cigarette users such as teenagers, may unknowingly become exposed to improper levels of nicotine, leading to a higher probability of nicotine dependence or switching to conventional smoking. The purpose of this study was to determine whether presence of nicotine can be detected in marketed nicotine-free electronic cigarette liquids. Methods: The nicotine content in electronic cigarette liquids was isolated and determined using Gas Chromatography Mass Spectrometry. Descriptive and inferential statistics was conducted using NCSS11 to see if there was a statistically significant difference between the labelled concentration of 0 mg in marketed “nicotine-free” electronic cigarettes from two popular brands, VapeWild and Mt Baker Vapour, to determine whether one brand has better quality control for nicotine content in nicotine-free E-liquids compared to the other brand. Results: Based on the analyzed E-liquid samples from the two brands, no nicotine was detected. Conclusion: E-cigarettes can be putatively considered as a safer alternative to conventional cigarettes because nicotine levels can be pre-determined and limited with a high degree of confidence.  

scholarly journals The earth is flat (p>0.05): Significance thresholds and the crisis of unreplicable research

2017 ◽  
Author(s):  
Valentin Amrhein ◽  
Fränzi Korner-Nievergelt ◽  
Tobias Roth
Keyword(s):  
Publication Bias ◽  
Null Hypothesis ◽  
Statistical Power ◽  
Alternative Hypothesis ◽  
Statistical Significance ◽  
Practical Importance ◽  
Decision Rules ◽  
Effect Sizes ◽  
P Values ◽  
True Effect

The widespread use of 'statistical significance' as a license for making a claim of a scientific finding leads to considerable distortion of the scientific process (American Statistical Association, Wasserstein & Lazar 2016). We review why degrading p-values into 'significant' and 'nonsignificant' contributes to making studies irreproducible, or to making them seem irreproducible. A major problem is that we tend to take small p-values at face value, but mistrust results with larger p-values. In either case, p-values can tell little about reliability of research, because they are hardly replicable even if an alternative hypothesis is true. Also significance (p≤0.05) is hardly replicable: at a realistic statistical power of 40%, given that there is a true effect, only one in six studies will significantly replicate the significant result of another study. Even at a good power of 80%, results from two studies will be conflicting, in terms of significance, in one third of the cases if there is a true effect. This means that a replication cannot be interpreted as having failed only because it is nonsignificant. Many apparent replication failures may thus reflect faulty judgement based on significance thresholds rather than a crisis of unreplicable research. Reliable conclusions on replicability and practical importance of a finding can only be drawn using cumulative evidence from multiple independent studies. However, applying significance thresholds makes cumulative knowledge unreliable. One reason is that with anything but ideal statistical power, significant effect sizes will be biased upwards. Interpreting inflated significant results while ignoring nonsignificant results will thus lead to wrong conclusions. But current incentives to hunt for significance lead to publication bias against nonsignificant findings. Data dredging, p-hacking and publication bias should be addressed by removing fixed significance thresholds. Consistent with the recommendations of the late Ronald Fisher, p-values should be interpreted as graded measures of the strength of evidence against the null hypothesis. Also larger p-values offer some evidence against the null hypothesis, and they cannot be interpreted as supporting the null hypothesis, falsely concluding that 'there is no effect'. Information on possible true effect sizes that are compatible with the data must be obtained from the observed effect size, e.g., from a sample average, and from a measure of uncertainty, such as a confidence interval. We review how confusion about interpretation of larger p-values can be traced back to historical disputes among the founders of modern statistics. We further discuss potential arguments against removing significance thresholds, such as 'we need more stringent decision rules', 'sample sizes will decrease' or 'we need to get rid of p-values'.

scholarly journals Analysis of the area and the number of pulmonary alveoli through the normal aging process in CD1 mouse

2020 ◽  
Author(s):  
Marta Ortega-Martínez ◽  
Esthefania Gutiérrez-Arenas ◽  
Vanessa Gutiérrez-Dávila ◽  
Alberto Niderhauser-García ◽  
Ricardo M Cerda-Flores ◽  
...  
Keyword(s):  
Aging Process ◽  
Structural Changes ◽  
Statistical Significance ◽  
Age Groups ◽  
Normal Aging ◽  
P Values ◽  
Pulmonary Alveoli ◽  
Significant Difference ◽  
Old Mice ◽  
Alveolar Area

During the aging process, the lung exhibits structural changes accompanied by a decline in its function. The related information currently available is still scarce and contradictory. In addition, changes in some pulmonary parameters through aging process are species- and strain- dependent. The aim of this study was the assessment of the area and the number of pulmonary alveoli through the normal aging process in CD1 mouse. Paraffin-embedded sections of lungs from CD1 mice at age of 2, 6, 12, 18, or 24 months were stained with hematoxylin and eosin and examined using a light microscope. Images were captured using a camera linked to an image analysis software to measure areas and count alveoli. There was a significant difference in the alveolar area among the ages analyzed (F=87.53, Sig.=0.000). The alveolar area of the 6-, 12-, 18-, and 24-month-old mice was significantly greater (all p values < 0.001) than in mice at 2 months of age. Also, the alveolar number was significantly different among the ages tested (F=3.21, Sig.=0.023). The number of alveoli in mice at 2 months of age was greater than in mice at all other age groups, reaching statistical significance when compared with the 6-, 12-, and 18-month-old mice ( p values of 0.044, 0.014, and 0.002, respectively). Thus, we observed an increase in alveolar area and a decrease in alveolar number through the aging process. This information might be useful to understand pathologic changes underlying susceptibility of elderly individuals to chronic lower respiratory tract diseases.

scholarly journals Comparison of Intralesional Meglumine Antimonite along withoral Itraconazole to Intralesional Meglumine Antimonitein the treatment of Cutaneous Leishmaniasis

2019 ◽  
Vol 35 (6) ◽  
Author(s):  
Uzma Bashir ◽  
Moizza Tahir ◽  
Muhammad Irfan Anwar ◽  
Faisal Manzoor
Keyword(s):  
Cutaneous Leishmaniasis ◽  
Clinical Cure ◽  
Statistical Significance ◽  
Military Hospital ◽  
P Values ◽  
Meglumine Antimoniate ◽  
Significant Difference ◽  
Group A ◽  
Oral Itraconazole ◽  
Group B

Background & Objective: Cutaneous leishmaniasis (CL) is endemic in developing countries like Pakistan. Pentavalent antimonials are still drug of choice, despite being toxic and intolerable for patients. Second line treatments have been extensively studied but the results of their efficacy are conflicting. This, to our knowledge, will be the first study in this regard. Our objective was to  determine if combination of oral itraconazole with intralesional (IL) meglumine antimoniate (MA) reduces the duration of treatment for cutaneous leishmaniasis, as compared to intralesional MA alone. Methods: A randomized controlled trial (single blinded) was carried out from August 2017 till December 2017 on 69 patients who fulfilled inclusion criteria. They were assigned to Group-A or B by lottery method. Group-A patients received IL MA once a week while Group-B received oral itraconazole 200mg, once daily, for six weeks along with similar regimen of IL MA as Group-A. The patients were assessed every three weeks by the blinded assessor till clinical cure was achieved. A follow up visit, two months after clinical cure was done to look for relapse of the disease. Results: Thirty patients in Group-A and 35 patients in Group-B completed the study. At 3, 6, 9 and 12 weeks the patients were assessed for: no, partial or complete response and results of the two groups were compared for statistical significance. The p-values of 0.20, 0.57 and 0.11 at 3, 6 and 9 weeks, respectively, depict that there was no significant difference at any step of assessment between the two groups in terms of healing. The p values of each t test was >0.05 refuting the hypothesis. Conclusion: Combination of oral itraconazole with intralesional MA offered no benefit over intralesional MA alone in the management of cutaneous leishmaniasis in terms of duration of therapy.  Abbreviations Used: IL = Intralesional,  MA = Meglumine Antimoniate, LD = Leishmania Donovan, CL = Cutaneous leishmaniasis, CMH = Combined Military Hospital. doi: https://doi.org/10.12669/pjms.35.6.363 How to cite this:Bashir U, Tahir M, Anwar MI, Manzoor F. Comparison of Intralesional Meglumine Antimonite along with oral Itraconazole to Intralesional Meglumine Antimonite in the treatment of Cutaneous Leishmaniasis. Pak J Med Sci. 2019;35(6):1669-1673.   doi: https://doi.org/10.12669/pjms.35.6.363 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

scholarly journals The Relationship Between of Cash Flows (Financing, Investment and Operating) and Stock Prices, Size of the Firms

2020 ◽  
Vol 11 (5) ◽  
pp. 424
Author(s):  
Tamer Bahjat Sabri ◽  
Khalid Mohammad Hasan Sweis ◽  
Issam Naim Mahammad Ayyash ◽  
Yasmeen Faheem Asaad Qalalwi ◽  
Israa Sami Abbas Abdullah
Keyword(s):  
Stock Returns ◽  
Stock Prices ◽  
Null Hypothesis ◽  
Stock Exchange ◽  
Statistical Significance ◽  
Nonparametric Test ◽  
Cash Flows ◽  
The Other ◽  
Significant Difference ◽  
The Relationship

This study sought to test the relationship between cash flows from operating activities, investment activities and financial activities and on one hand and stock returns and the volume of assets on the companies listed in Palestine Stock Exchange on the other hand. The study incorporated 24 companies in 2018 and the required data were obtained through the financial statements. To test the hypotheses of the study, the Mann-Whitny U Test was used, a nonparametric test. Also the Kolmogorov-Smirnov was done. The findings demonstrated that the value of the Whitny U Test was (-3.291) Z with a statistical significance at 1%. Based on this, the null hypothesis was rejected and the alternative one, stating that there is a statistically significant difference between the operating flows of companies with low assets and those companies with high assets, was accepted. However, the other null hypothesis was accepted. The study recommended that companies and investors should take into consideration cash flows when taking an investment decision in Palestine Stock Exchange.

scholarly journals 1379. Comparison of Inpatient Tuberculosis Screening Methods and Their Effect on Patient Duration in Airborne Isolation

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S501-S501
Author(s):  
Mary Katherine. Theoktisto ◽  
Delvina Ford ◽  
Omar Khan ◽  
Kelly R Reveles ◽  
Jose Cadena
Keyword(s):  
Statistical Significance ◽  
Nucleic Acid Amplification ◽  
Health Concern ◽  
Smear Microscopy ◽  
Screening Methods ◽  
Number Of Patients ◽  
Significant Difference ◽  
Group A ◽  
Group B ◽  
Crude Analysis

Abstract Background Tuberculosis (TB) remains a significant public health concern, and exposure in healthcare settings is prevalent. Current guidelines recommend testing for TB by acid-fast bacilli (AFB) smear microscopy with 3 sputum samples and/or using nucleic acid amplification test (NAAT), and mycobacterium culture. The purpose of this project is to compare how different TB diagnostic tests affect the duration of stay in respiratory isolation. Methods This study was conducted at the Veteran Affairs South Texas hospital, which includes a total of 437 beds. Data were collected retrospectively from medical records. Eligibility included patients admitted to the hospital and placed in airborne isolation for TB screening and diagnosis, had 3 sputum samples collected 8 hours apart and/or had 2 PCR MTB/RIF. Patients were excluded if they had TB or were not undergoing evaluation for TB. Three time periods analyzed included, 3 AFB sputum samples analyzed in-house from December 2012 to January 2014 (Group A), 3 AFB sputum samples analyzed at outside facility during 2013 to 2014 as well as 2 months in 2012 (Group B), and 2 MTB PCR/RIF in house during 2017 and 2018 (Group C). Duration of isolation was compared between groups using the Kruskal–Wallis test. A total number of 815 patients were screened, leaving 105 patients for analysis after exclusion. There were 49 patients analyzed from Group A, 28 from Group B, and 28 from Group C. Results Crude analysis of the data showed numerical differences in the total number of days and hours in isolation between the 3 groups. The average (mean) days in isolation were 4.2 for Group A, 7.4 for Group B, and 5.5 for Group C. There was no statistically significant difference in either days or hours of airborne precautions by “rule out” method. Days of isolation in airborne precautions (median IQR) was 4 for all groups (P = 0.3313). Likewise, hours of airborne precautions had a median IQR of 96 for all groups P = 0.4347. Conclusion Although there was no statistical significance between the groups, crude analysis did show a numerical difference in the mean total airborne days and hours. Lack of statistical difference may be due to low number of patients, timing of order placement for in-house PCR, and longer than expected stay in airborne precautions. Disclosures All authors: No reported disclosures.

scholarly journals The earth is flat (p>0.05): Significance thresholds and the crisis of unreplicable research

2017 ◽  
Author(s):  
Valentin Amrhein ◽  
Fränzi Korner-Nievergelt ◽  
Tobias Roth
Keyword(s):  
Publication Bias ◽  
Null Hypothesis ◽  
Statistical Power ◽  
Statistical Significance ◽  
Practical Importance ◽  
Effect Sizes ◽  
Selective Reporting ◽  
Interval Estimate ◽  
P Values ◽  
True Effect

The widespread use of 'statistical significance' as a license for making a claim of a scientific finding leads to considerable distortion of the scientific process (according to the American Statistical Association). We review why degrading p-values into 'significant' and 'nonsignificant' contributes to making studies irreproducible, or to making them seem irreproducible. A major problem is that we tend to take small p-values at face value, but mistrust results with larger p-values. In either case, p-values tell little about reliability of research, because they are hardly replicable even if an alternative hypothesis is true. Also significance (p≤0.05) is hardly replicable: at a good statistical power of 80%, two studies will be 'conflicting', meaning that one is significant and the other is not, in one third of the cases if there is a true effect. A replication can therefore not be interpreted as having failed only because it is nonsignificant. Many apparent replication failures may thus reflect faulty judgment based on significance thresholds rather than a crisis of unreplicable research. Reliable conclusions on replicability and practical importance of a finding can only be drawn using cumulative evidence from multiple independent studies. However, applying significance thresholds makes cumulative knowledge unreliable. One reason is that with anything but ideal statistical power, significant effect sizes will be biased upwards. Interpreting inflated significant results while ignoring nonsignificant results will thus lead to wrong conclusions. But current incentives to hunt for significance lead to selective reporting and to publication bias against nonsignificant findings. Data dredging, p-hacking, and publication bias should be addressed by removing fixed significance thresholds. Consistent with the recommendations of the late Ronald Fisher, p-values should be interpreted as graded measures of the strength of evidence against the null hypothesis. Also larger p-values offer some evidence against the null hypothesis, and they cannot be interpreted as supporting the null hypothesis, falsely concluding that 'there is no effect'. Information on possible true effect sizes that are compatible with the data must be obtained from the point estimate, e.g., from a sample average, and from the interval estimate, such as a confidence interval. We review how confusion about interpretation of larger p-values can be traced back to historical disputes among the founders of modern statistics. We further discuss potential arguments against removing significance thresholds, for example that decision rules should rather be more stringent, that sample sizes could decrease, or that p-values should better be completely abandoned. We conclude that whatever method of statistical inference we use, dichotomous threshold thinking must give way to non-automated informed judgment.

scholarly journals A Prototypical First-Generation Electronic Cigarette Does Not Reduce Reports of Tobacco Urges or Withdrawal Symptoms among Cigarette Smokers

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Arit M. Harvanko ◽  
Catherine A. Martin ◽  
Richard J. Kryscio ◽  
William W. Stoops ◽  
Joshua A. Lile ◽  
...  
Keyword(s):  
First Generation ◽  
Electronic Cigarettes ◽  
Electronic Cigarette ◽  
Withdrawal Symptoms ◽  
Cigarette Smokers ◽  
Deprivation Period ◽  
Nicotine Concentration ◽  
Tobacco Cigarette ◽  
Within Subjects

It is unknown whether first-generation electronic cigarettes reduce smoking urges and withdrawal symptoms following a 24 h deprivation period. This study tested whether a first-generation electronic cigarette reduces smoking urges and withdrawal symptoms in cigarette smokers. Following 24 h of tobacco deprivation, using a within-subjects design, eight nontreatment seeking tobacco cigarette smokers (3 females) administered 10 puffs from a conventional cigarette or a first-generation electronic cigarette containing liquid with 0, 8 or 16 mg/ml nicotine. Conventional cigarettes ameliorated smoking urges and electronic cigarettes did not, regardless of nicotine concentration. First-generation electronic cigarettes may not effectively substitute for conventional cigarettes in reducing smoking urges, regardless of nicotine concentration.

scholarly journals Assessment of knowledge, attitude and practices on antibiotic resistance among undergraduate medical students in the school of medicine at the University of Zambia

2020 ◽  
Vol 9 (2) ◽  
pp. 263 ◽  
Author(s):  
Annie Zulu ◽  
Scott K. Matafwali ◽  
Michelo Banda ◽  
Steward Mudenda
Keyword(s):  
Antibiotic Resistance ◽  
Medical Students ◽  
Statistical Significance ◽  
Health Concern ◽  
Good Knowledge ◽  
Global Public Health ◽  
Undergraduate Medical Students ◽  
Good Practices ◽  
Significant Difference ◽  
The University

Background: The issue of antibiotic resistance has become a global public health concern, with an extensive clinical and economic burden. The study aimed to assess the knowledge, attitude, and practices of antibiotic resistance among undergraduate medical students at the University of Zambia.Methods: This cross-sectional study was conducted at the University of Zambia Ridgeway Campus. A structured questionnaire was administered to 260 randomly selected undergraduate medical students. Data were analyzed using Statistical Package for Social Sciences (SPSS) version 22.0. Associations between dependent and independent variables were done using a Chi-square test. The statistical significance was done at 95% confidence level (p<0.05). Ethical approval was done by the University of Zambia Health Sciences Research Ethics Committee.Results: The study found that 227 of 260 (87.3%) of the medical students had good knowledge on antibiotic use and resistance. The majority of the medical students 252 of 260 (96.9%) had positive attitudes and 195 of 260 (75%) had good practices towards antibiotic resistance. There was a significant difference between the year of study and the level of knowledge (χ2=16.333, p=0.003). There was no significant difference between the year of study and the attitude of the participants (χ2=4.061, p=0.398). A significant difference was found between the year of study and the practices of the respondents (χ2=10.926, p=0.027).Conclusions: The medical students had good knowledge, a positive attitude, and good practices towards antibiotic resistance. Final year students had higher levels of knowledge and attitude but lower levels of practice compared to other years of study.

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