scholarly journals StaTips Part VIII: Confidence interval for the sample mean

2020 ◽  
Vol 7 (1) ◽  
pp. 2-3
Author(s):  
Giuseppe Perinetti
Keyword(s):  
Confidence Interval ◽  
Small Group ◽  
Statistical Significance ◽  
P Value ◽  
Sample Mean ◽  
Type Population ◽  
The Difference ◽  
Conducting Research

When conducting research on a given type of patients, it is impossible to examine all the existing subjects of that type (population)to derive the true mean of the parameter of interest. More realistically, by the investigation of a small group of subjects (sample) fromthe whole population, researchers can estimate an interval into which the true mean of the population lies. In statistics, such interval isreferred to as confidence interval (CI). The calculation of the CI from a sample mean is simple and gives important information, not onlyregarding the true mean of the population, but also on the statistical significance of the difference between groups being compared. Forthese reasons, the reporting of the CIs is preferred over the p value alone.

scholarly journals Understanding the Difference Between Standard Deviation and Standard Error of the Mean, and Knowing When to Use Which

2020 ◽  
Vol 42 (4) ◽  
pp. 409-410
Author(s):  
Chittaranjan Andrade
Keyword(s):  
Standard Deviation ◽  
Confidence Interval ◽  
Standard Error ◽  
Statistical Significance ◽  
Sample Mean ◽  
Population Mean ◽  
Sample Data ◽  
The Mean ◽  
The Difference

Many authors are unsure of whether to present the mean along with the standard deviation (SD) or along with the standard error of the mean (SEM). The SD is a descriptive statistic that estimates the scatter of values around the sample mean; hence, the SD describes the sample. In contrast, the SEM is an estimate of how close the sample mean is to the population mean; it is an intermediate term in the calculation of the 95% confidence interval around the mean, and (where applicable) statistical significance; the SEM does not describe the sample. Therefore, the mean should always be accompanied by the SD when describing the sample. There are many reasons why the SEM continues to be reported, and it is argued that none of these is justifiable. In fact, presentation of SEMs may mislead readers into believing that the sample data are more precise than they actually are. Given that the standard error is not presented for other parameters, such as difference between means or proportions, and difference between proportions, it is suggested that presentation of SEM values can be done away with, altogether.

Effect of Ultrasound and Calf Stretching in relieving Gastrocnemius Tightness in subjects with Plantar Fascitis

2021 ◽  
pp. 3025-3028
Author(s):  
Sowmya M V ◽  
Nandhini S ◽  
Manigandan V
Keyword(s):  
Functional Ability ◽  
Combined Therapy ◽  
Statistical Significance ◽  
Mean Value ◽  
P Value ◽  
Functional Activities ◽  
Post Test ◽  
Foot Function ◽  
The Difference ◽  
Gastrocnemius Tightness

Objective: To evaluate the efficacy of ultrasound and calf stretching in subjects with gastrocnemius tightness in plantar fascitis to reduce pain and improve functional ability. Method: 30 patients with plantar fascitis selected from Saveetha college of physiotherapy and rehabilitation center (SPARC) based on inclusion and exclusion criteria. The patients were treated with ultrasound therapy and calf stretching. The pre and post test values of pain and functional ability was be calculated using Silfverskiold test and Foot Function Index as an outcome measure. Results: The mean value and standard errors were calculated for different variables and the difference in mean value was tested for statistical significance using paired t test. P value of <0.0001 was considered as statistically significant. Conclusion: From the statistical analysis and graphical interpretation the final derived results concluded that combined therapy of ultrasound and calf stretching is found to be effective in relieving gastrocnemius tightness in patient suffering with plantar fascitis and it can be used to improve the functional activities.

Clinical Trial Assessment of Intermittent and Continuous Infusion Dose of N-Acetylcysteine on Redox Status of the Body in Patients with Sepsis Admitted to the ICU

2019 ◽  
Vol 35 (12) ◽  
pp. 1383-1388 ◽  
Author(s):  
Arash Peivandi Yazdi ◽  
Majid Razavi ◽  
Shahrzad Sheikh ◽  
Nadia Boroumand ◽  
Maryam Salehi ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Continuous Infusion ◽  
Statistical Significance ◽  
Redox Status ◽  
Group Iv ◽  
P Value ◽  
Antioxidative Effect ◽  
Infusion Group ◽  
Acetyl Cysteine ◽  
The Difference

Purpose: Conflicting results exist regarding the efficacy of N-acetyl cysteine (NAC) in sepsis treatment. A pivotal factor affecting the therapeutic potency of NAC in sepsis is timing and dosing of its infusion. We aimed to assess the effect of NAC on redox status of patients with sepsis and to compare its efficacy in intermittent and continuous infusion with the objective of developing the infusion regimen and optimizing the timing. Materials and Methods: A prospective, randomized clinical trial was designed to compare the antioxidative effect of NAC in intermittent infusion group (IV: 25 mg/kg bolus and then 25 mg/kg/8 hours 3 times) and continuous infusion group (IV: 25 mg/kg bolus and then 75 mg/kg over 24 hours) in 60 critically ill patients with sepsis (20 patients in each group). Blood samples were collected immediately before and after intervention for total antioxidant capacity (TAC) and malondialdehyde (MDA) assessment. Results: N-acetyl cysteine considerably increased TAC levels in both intermittent (0.68 ± 0.60; P value = .036) and continuous (0.69 ± 0.64; P value = .015) infusion groups when compared to placebo (0.61 ± 0.10); however, the difference in TAC levels between the intermittent and the continuous infusion did not reach statistical significance ( P value = .942). Likewise, NAC treatment decreased MDA levels in both intermittent (19.45 ± 4.18; P value = 0.001) and continuous (22.47 ± 6.68; P value = .002) infusion groups when compared to placebo (31.76 ± 11.06), while the difference in MDA levels between the intermittent and the continuous infusion did not reach statistical significance ( P value = .481). Conclusion: Our data confirmed the antioxidative effect of NAC treatment in patients with sepsis, with no significant difference in intermittent and continuous infusion.

scholarly journals Hyperuricemia is a risk factor for cardiovascular risk?

2019 ◽  
Vol 7 (5) ◽  
pp. 1562
Author(s):  
Venkata Krisnan ◽  
Bhimasen Soren ◽  
K. Ramalingam ◽  
M. Prasad Naidu ◽  
Akhil G. ◽  
...  
Keyword(s):  
Uric Acid ◽  
Confidence Interval ◽  
General Medicine ◽  
Biochemical Parameter ◽  
Urate Oxidase ◽  
P Value ◽  
Cvd Risk ◽  
Equality Of Means ◽  
The Difference ◽  
One Year

Background: Uric acid is the end product of purine metabolism in humans degraded by the hepatic enzyme, urate oxidase (uricase), to allantoin, which is freely excreted in the urine. However, during the Miocene epoch (20 to 5 million years ago), 2 parallel but distinct mutations occurred in early hominoids that rendered the uricase gene non-functional. Uric acid (UA) is a known endogenous scavenger, which provides a major part of the antioxidant capacity against oxidative and radical injury.Methods: The present study was conducted over a period of one year on outpatients attending the General Medicine Department at Narayana General Hospital, Nellore. The study was included 998 subjects (500 male and 498 female) and authors excluded other complications. Data were analyzed by SPSS software.Results: Serum uric acid of the subjects were measured. The mean and standard deviation were calculated for all the Biochemical parameter. The significance between the groups was determined using Student t-test for equality of means. The two-tailed P value is less than 0.0001, which is statistically significant. Confidence interval: the hypothetical mean is 1.0000 and the actual mean is 6.4600. The difference between these two values is 5.4600. The 95% confidence interval of this difference from 5.3489 to 5.5711. Intermediate values used in calculations; t = 96.4583, df = 999 and standard error of difference p = 0.057.Conclusions: About 53% of the subjects of the study are hyperuricemia, with about 74% of these subjects (or about 39% of the total) diagnosed with hypertension or diabetes mellitus or both, indicating a high CVD risk.

scholarly journals Visualization Strategies for Regression Estimates with Randomization Inference

2019 ◽  
Author(s):  
Marshall A. Taylor
Keyword(s):  
Confidence Interval ◽  
Confidence Intervals ◽  
Regression Models ◽  
Statistical Significance ◽  
Permutation Tests ◽  
P Value ◽  
P Values ◽  
Alpha Level ◽  
Significance Levels ◽  
Nonprobability Sample

Coefficient plots are a popular tool for visualizing regression estimates. The appeal of these plots is that they visualize confidence intervals around the estimates and generally center the plot around zero, meaning that any estimate that crosses zero is statistically non-significant at at least the alpha-level around which the confidence intervals are constructed. For models with statistical significance levels determined via randomization models of inference and for which there is no standard error or confidence intervals for the estimate itself, these plots appear less useful. In this paper, I illustrate a variant of the coefficient plot for regression models with p-values constructed using permutation tests. These visualizations plot each estimate's p-value and its associated confidence interval in relation to a specified alpha-level. These plots can help the analyst interpret and report both the statistical and substantive significance of their models. Illustrations are provided using a nonprobability sample of activists and participants at a 1962 anti-Communism school.

The Influence of Breast Cancer on the Distribution of Cherry Angiomas on the Anterior Thoracic Wall: A Case Series Study

Dermatology ◽  
2018 ◽  
Vol 235 (1) ◽  
pp. 65-70 ◽  
Author(s):  
Antonio Guastafierro ◽  
Vincenzo Verdura ◽  
Bruno Di Pace ◽  
Mario Faenza ◽  
Corrado Rubino
Keyword(s):  
Breast Cancer ◽  
Statistical Significance ◽  
Case Series ◽  
Thoracic Wall ◽  
Rank Test ◽  
P Value ◽  
Unilateral Breast Cancer ◽  
Case Series Study ◽  
Signed Rank Test ◽  
The Difference

Background/Aims: Cherry angiomas (CAs) are one of the most common vascular manifestations of the skin. By and large, these benign lesions often only represent an aesthetic problem. In the literature, few authors have focused on the pathogenesis of these lesions, and some risk factors have been identified, such as the presence of cutaneous and non-skin neoplasias. In this study, the correlation between the distribution of CAs and breast cancer was investigated. Methods: We carried out a study whereby 50 women with unilateral breast cancer and the presence of CAs on the anterior thoracic wall were evaluated, with a particular focus on the difference in the number of CAs between the two haemithoraces. The data was elaborated using the Wilcoxon signed-rank test in order to evaluate whether there was a statistical significance in the distribution of CAs. Results: In 31 patients we found that the number of CAs was greater on the cancerous breast than on the contralateral one (p value <0.0001). This was confirmed both in the group of patients suffering from ductal breast cancer and in the group with early invasive breast tumours. Conclusion: It is not clear whether CAs develop prior to or following breast cancer, indicating the possibility that this cutaneous manifestation could take on a predictive, prognostic development or represent only an epiphenomenon. Further in-depth studies into the pathogenesis of CAs and the relationship with breast cancer could lead to noteworthy diagnostic-therapeutic advances.

scholarly journals Effect size: commentary to the study on the Factors associated with the practice of exclusive breastfeeding

2020 ◽  
Author(s):  
Marisol Angulo-Ramos ◽  
César Merino-Soto
Keyword(s):  
Statistical Significance ◽  
Numerical Data ◽  
Practical Significance ◽  
Logistic Distribution ◽  
P Value ◽  
Knowledge And Skills ◽  
Instructional Content ◽  
The Difference ◽  
In Pregnancy

This letter focuses on recent and interesting work on breastfeeding, to emphasize two observations. The first observation refers to the fact that, in Mateus and Cabrera’s manuscript It was hardly discussed whether the referred knowledge and skills may be relevant to understanding the mothers’ behavior regarding their commitment to breastfeeding. The relevance of these cognitive aspects requires more attention due to their relationship with breastfeeding practices, and in general with the long-term mother-infant dyad. Because the knowledge and skills to maintain successful breastfeeding have implications for developing instructional content in interventions for mothers as well, great attention needs to be paid to the size of the effect of differences between reported frequencies in pregnancy and the immediate puerperium. In Table 3, these differences were examined by the McNemar statistical test, which allows obtaining the statistical significance of the rejection of the null hypothesis of no differences. But neither this test nor the size of its p-value inform about the degree or size of the differences. An estimate of the size or magnitude of the differences, represented as point values or confidence intervals (as reported in Tables 4 and 5), tend to better specify tests of statistical significance. Therefore, we estimate the practical significance of the difference between the percentages obtained in pregnancy and the immediate puerperium for each of the knowledge and basic skills reported in Table 3. With the only numerical data presented in this table, we calculated the McNemar odd ratio (McNemar OR , and standardized difference measures d: d Cox 8 and d probit . These show less bias with their population values in relation to other estimators5. Because they both assume different statistical assumptions e.g., logistic distribution for McNemar OR and d Cox , and normal distribution for d probit , calculating both will report the convergence or divergence of these estimates.

scholarly journals Factors associated with non-vaccination against measles among 12-23 months old children in Yirgachefe district of SNNPR, Ethiopia, 2016

2020 ◽  
Author(s):  
Luna Habtamu Degife ◽  
Yoseph Worku ◽  
Muse Tadesse
Keyword(s):  
Confidence Interval ◽  
Odds Ratio ◽  
Statistical Significance ◽  
Southern Ethiopia ◽  
Effective Vaccine ◽  
P Value ◽  
Age Group ◽  
Factors Associated ◽  
Measles Vaccination

Abstract Immunization is an effective and proven tool for controlling and eliminating life-threatening vaccine preventable infectious diseases. In Ethiopia 5% of childhood mortalities are due to measles. Despite the availability of a safe and effective vaccine, measles outbreaks secondary to non-vaccination are occurring in southern Ethiopia especially in Yirgachefe district. This study was done to assess the risk factors associated with non-vaccination against measles. A Community-based unmatched case control study was conducted in Yirgachefe district from December 1-31, 2016.Cases were children in the age group of 12- 23 months of age who did not take measles vaccination and controls were children in the same age group who took at least one dose of measles vaccine. The study was done in 6 randomly selected kebeles and cases and controls were selected randomly by probability proportional to size sampling. A structured questionnaire was used for data collection. Statistical significance was interpreted using Odds ratio with 95% confidence interval and P value <0.05.A total of 320 individuals (107 cases and 214 controls) were approached for interview with a response rate of 93.75%. Of the cases, 57% were males and more than half fall in the 12-18 months age group. Knowledge regarding measles vaccination was also asked and among cases 72% heard about measles, 26% knew that all children should be vaccinated, 31% had awareness about the right age of vaccination, 60% agrees that measles is vaccine preventable and 65% knew that it is contagious. In multivariable logistic regression, Lack of Ante Natal Care follow up(ANC) (Adjusted Odds Ratio (AOR) =3.57; 95% Confidence Interval (CI): 1.22-10.44), lack of knowledge on the importance of vaccination, who should be vaccinated and if measles is contagious with an AOR and CI of (AOR=6.81; 95% CI: 1.56-29.64), (AOR=4.29; 95% CI: 1.83-10.04) and (AOR=8.97; 95%CI: 3.15-25.58) respectively were independent risk factors.Education and awareness about measles and its immunization should be given to the community. Additionally, ANC follow up should also be strengthened.

scholarly journals Community Based Health Insurance Enrollment and Associated Factors in Sidama Region, Ethiopia

2020 ◽  
Author(s):  
Berhanu Bifato ◽  
Amanuel Ayele ◽  
Muse Rike ◽  
Dalecha Dangura
Keyword(s):  
Health Insurance ◽  
Confidence Interval ◽  
Low Income ◽  
Associated Factors ◽  
Statistical Significance ◽  
Multivariable Analysis ◽  
P Value ◽  
Community Based ◽  
Community Based Health Insurance ◽  
Insurance Enrollment

Abstract Background: Community based health insurance is accepted as a capable tool of health system improvement and improves the health status of enrollees. Its mechanisms look for to protect low-income households from health related risks through mutual risk sharing at the community level. Even though Government’s efforts, the Community based health insurance enrolment rate remained low. Objective: To assess the community based health insurance enrollment and associated factors in Sidama Region, Ethiopia.Methods: A community based cross-sectional study was conducted in Sidama Region, 2020 using a pretested structured questionnaire. The study was conducted in randomly selected 770 households. The data entry was made by using Epi-info 2007 software. The data was analyzed by using SPSS version 20. Logistic regression statistical model was used to compute odds ratio with its 95% confidence interval to test the associations between dependent and independent variables. Then variables found to have P<0.25 in the bi-variable analysis taken as candidate for multivariable analysis. A P-value of 0.05 with a confidence interval of 95% was used to declare level of statistical significance. Result: Among 770 sampled households, 762 were interviewed and the response rate was 98.9%. About 20.2% of the respondents were enrolled in the scheme. Covariates such as፡ ages 31-59 years(AOR :2.62, 95% CI :1.48-4.66)and >=60 years(AOR : 2.87, 95% CI :1.23-6.74), households who had no formal education(AOR:1.66, 95% CI:1.02-2.72),affordability of premium (AOR:0.28, 95% CI: 0.15-0.54), knowledge on CBHI(AOR: 3.53; 95% CI: 1.21, 10.27) and perceived quality(AOR: 0.52, 95% CI: 0.25-0.87) had statistically significant association with community based health insurance enrollment.Conclusion: The prevalence of community based health insurance enrollment was low. This study identified the need to create knowledge and bring behavioral change in the community on the scheme in general. This study also revealed that regular contribution issue needs improvement based on affordability of households and building their trust on the program and efforts should be devoted to enhance quality of healthcare services to increase the enrollment.

scholarly journals Visualization strategies for regression estimates with randomization inference

2020 ◽  
Vol 20 (2) ◽  
pp. 309-335
Author(s):  
Marshall A. Taylor
Keyword(s):  
Confidence Interval ◽  
Confidence Intervals ◽  
Regression Models ◽  
Statistical Significance ◽  
Permutation Tests ◽  
P Value ◽  
P Values ◽  
Alpha Level ◽  
Significance Levels ◽  
Nonprobability Sample

Coefficient plots are a popular tool for visualizing regression estimates. The appeal of these plots is that they visualize confidence intervals around the estimates and generally center the plot around zero, meaning that any estimate that crosses zero is statistically nonsignificant at least at the alpha level around which the confidence intervals are constructed. For models with statistical significance levels determined via randomization models of inference and for which there is no standard error or confidence intervals for the estimate itself, these plots appear less useful. In this article, I illustrate a variant of the coefficient plot for regression models with p-values constructed using permutation tests. These visualizations plot each estimate’s p-value and its associated confidence interval in relation to a specified alpha level. These plots can help the analyst interpret and report the statistical and substantive significances of their models. I illustrate using a nonprobability sample of activists and participants at a 1962 anticommunism school.

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