An introduction to power and sample size estimation

Jones, Stephen R.; Carley, Simon; Harrison, Michael

doi:10.1136/emj.20.5.453

Cited by 513 publications

(400 citation statements)

References 4 publications

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“…[20][21][22] Based on these data we used a standard deviation (SD) for cosmesis scores of 15 mm and calculated that with 30 subjects in each group, with an alpha error of 0.05, we would have 90% power to detect a 13-mm difference in cosmesis scores. 23 Using the confidence interval (CI) approach, noninferiority can be concluded if the absolute value for the lower boundary of the 95% CI for the difference in means between the two groups does not exceed 13 mm.…”

Section: Resultsmentioning

confidence: 99%

A Comparison of Cosmetic Outcomes of Lacerations on the Extremities and Trunk Using Absorbable Versus Nonabsorbable Sutures

Tejani

Sivitz

Rosen

et al. 2014

Academic Emergency Medicine

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Objectives: The primary objective was to compare the cosmetic outcomes of traumatic trunk and extremity lacerations repaired using absorbable versus nonabsorbable sutures. The secondary objective was to compare complication rates between the two groups.Methods: This was a randomized controlled trial comparing wounds repaired with Vicryl Rapide and Prolene sutures. Pediatric and adult patients with lacerations were enrolled in the study. At a 10-day follow-up, the wounds were evaluated for infection and dehiscence. After 3 months, patients returned to have the wounds photographed. Two plastic surgeons blinded to the method of closure rated the cosmetic outcome of each wound using a 100-mm visual analog scale (VAS). Using a noninferiority design, a VAS score of 13 mm or greater was considered to be a clinically significant difference. We used a Student's t-test to compare differences between mean VAS scores and odds ratios (ORs) to compare differences in complication rates between the two groups.Results: Of the 115 patients enrolled, 73 completed the study including 35 in the Vicryl Rapide group and 38 in the Prolene group. The mean (AESD) age of patients who completed the study was 22.1 (AE15.5) years, and 39 were male. We found no significant differences in the age, race, sex, length of wound, number of sutures, or layers of repair in the two groups. The observer's mean VAS for the Vicryl Rapide group was 54.1 mm (95% confidence interval [CI] = 44.5 to 67.0 mm) and for the Prolene group was 54.5 mm (95% CI = 45.7 to 66.3 mm). The resulting mean difference was 0.5 mm (95% CI = -12.1 to 17.2 mm; p = 0.9); thus noninferiority was established. Statistical testing showed no differences in the rates of complications between the two groups, but a higher percentage of the Vicryl Rapide wounds developed complications. Conclusions:The use of absorbable sutures for the repair of simple lacerations on the trunk and extremities should be considered as an alternative to nonabsorbable suture repair.ACADEMIC EMERGENCY MEDICINE 2014;21:637-643

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Section: Resultsmentioning

confidence: 99%

A Comparison of Cosmetic Outcomes of Lacerations on the Extremities and Trunk Using Absorbable Versus Nonabsorbable Sutures

Tejani

Sivitz

Rosen

et al. 2014

Academic Emergency Medicine

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“…A repeated measures t-test was conducted pre and post intervention with students and teacher participants. Estimates of the sample size required to achieve a power of .8, and a medium effect size of at least .5 indicated that the subject group needed to be at least 26 subjects to compare mean scores pre and post intervention (Jones, Carley, & Harrison, 2003).…”

Section: Resultsmentioning

confidence: 99%

Brief Online Classroom Behavior Management Training for Teachers to Address Male Student Behavioural Issue in Chennai, India

Teoh¹,

Cheong²,

Stuart³

et al. 2018

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When teachers require on-going coaching in the management of students' behaviours, Tele-Education may be used to bridge this competency gap. India's education policy has had considerable success in increasing students, from rural and disadvantaged areas, participating and completing secondary schooling. However, it has also resulted in higher numbers of students with challenging classroom behaviours. Behavior management is not well addressed in the current national plan and little training is provided to teachers. Previous research on students defined the behavioural management issues as well as the skills requirements for teachers to manage and provide positive behavioural management. As a result, three brief online training modules were developed and three real time behavior management case discussions were provided to assist teachers (n = 10) to manage challenging behaviours by male students (n = 50) in a pre and post intervention single group design. The Tele-Educational intervention increased teacher application of behavior management principles and improved classroom behavior in young males, suggesting potential for the approach to be utilised in other parts of India or in other countries where there is a need for this training.

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“…58 However, by using animals that have reached a plateau of unacceptable recovery at 3 months (as defined above), a 10% difference in recovery between control and treated animals could be detected with a power of 0.8 using as few as 30 dogs per group. 92 On assuming a spontaneous 50% recovery after loss of 'deep pain perception' following acute intervertebral disc extrusion, a 20% difference in proportion of recovering animals could be detected with a power of 0.8 with 60 dogs in each group. Bearing in mind the high incidence of SCI in dogs, both these group sizes can readily be attained.…”

Section: Patient Selectionmentioning

confidence: 97%

Clinical canine spinal cord injury provides an opportunity to examine the issues in translating laboratory techniques into practical therapy

et al. 2006

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Study design: Review. Objectives: To highlight the value of investigating the effects of putative therapeutic interventions in clinical spinal cord injury (SCI) in domestic dogs. Setting: England, UK. Methods: Many experimental interventions in laboratory rodents have been shown to ameliorate the functional deficits caused by SCI; the challenge now is to determine whether they can be translated into useful clinical techniques. Important differences between clinical SCI in human patients and that in laboratory rodents are in the size of the spinal cord and heterogeneity of injury severity. A further key issue is whether the statistical difference in outcome in the laboratory will translate into a useful difference in clinical outcome. Here, we stress the value of investigating the effects of putative therapies in clinical SCI in domestic dogs. The causes of injury, ability to categorise the severity and methods available to measure outcome are very similar between canine and human patients. Furthermore, postmortem tissue more rapidly becomes available from dogs because of their short lifespan than from human patients. Results: The role that investigation of canine SCI might play is illustrated by our preliminary trials on intraspinal transplantation of olfactory glial cells for severe SCI. Conclusions: This canine translational model provides a means of 'filtering' putative treatments before human application.

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An introduction to power and sample size estimation

Abstract: The importance of power and sample size estimation for study design and analysis.

Cited by 513 publications

References 4 publications

A Comparison of Cosmetic Outcomes of Lacerations on the Extremities and Trunk Using Absorbable Versus Nonabsorbable Sutures

A Comparison of Cosmetic Outcomes of Lacerations on the Extremities and Trunk Using Absorbable Versus Nonabsorbable Sutures

Brief Online Classroom Behavior Management Training for Teachers to Address Male Student Behavioural Issue in Chennai, India

Clinical canine spinal cord injury provides an opportunity to examine the issues in translating laboratory techniques into practical therapy

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