Sample Size Calculation for Poisson Endpoint Using the Exact Distribution of Difference Between Two Poisson Random Variables

2011 ◽  
Vol 3 (3) ◽  
pp. 497-504 ◽  
Author(s):  
Sandeep Menon ◽  
Joseph Massaro ◽  
Jerry Lewis ◽  
Michael Pencina ◽  
Yong-Cheng Wang ◽  
...  
Keyword(s):  
Sample Size ◽  
Sample Size Calculation ◽  
Random Variables ◽  
Exact Distribution

A Note on the Accuracy of Normal Approximation of Random Quantities

2021 ◽  
Vol 73 (1) ◽  
pp. 62-67
Author(s):  
Ibrahim A. Ahmad ◽  
A. R. Mugdadi
Keyword(s):  
Sample Size ◽  
Order Statistic ◽  
Normal Approximation ◽  
Order Approximation ◽  
Random Variables ◽  
Random Variable ◽  
Limiting Distribution ◽  
Exact Order ◽  
Fixed Sample ◽  
Independent Identically Distributed

For a sequence of independent, identically distributed random variable (iid rv's) [Formula: see text] and a sequence of integer-valued random variables [Formula: see text], define the random quantiles as [Formula: see text], where [Formula: see text] denote the largest integer less than or equal to [Formula: see text], and [Formula: see text] the [Formula: see text]th order statistic in a sample [Formula: see text] and [Formula: see text]. In this note, the limiting distribution and its exact order approximation are obtained for [Formula: see text]. The limiting distribution result we obtain extends the work of several including Wretman[Formula: see text]. The exact order of normal approximation generalizes the fixed sample size results of Reiss[Formula: see text]. AMS 2000 subject classification: 60F12; 60F05; 62G30.

The most frequently asked question to a statistician: The sample size

2017 ◽  
Vol 23 (5) ◽  
pp. 644-646 ◽  
Author(s):  
Maria Pia Sormani
Keyword(s):  
Clinical Study ◽  
Sample Size ◽  
Study Design ◽  
Treatment Effect ◽  
Sample Size Calculation ◽  
Ethical Implications ◽  
Number Of Patients ◽  
Reducing Costs ◽  
Correct Size

The calculation of the sample size needed for a clinical study is the challenge most frequently put to statisticians, and it is one of the most relevant issues in the study design. The correct size of the study sample optimizes the number of patients needed to get the result, that is, to detect the minimum treatment effect that is clinically relevant. Minimizing the sample size of a study has the advantage of reducing costs, enhancing feasibility, and also has ethical implications. In this brief report, I will explore the main concepts on which the sample size calculation is based.

Sample size calculation for clinical trials in which entry criteria and outcomes are counts of events

1994 ◽  
Vol 13 (8) ◽  
pp. 859-870 ◽  
Author(s):  
Robert P. McMahon ◽  
Michael Proschan ◽  
Nancy L. Geller ◽  
Peter H. Stone ◽  
George Sopko
Keyword(s):  
Clinical Trials ◽  
Sample Size ◽  
Sample Size Calculation

scholarly journals Prevalence of Ectopic Eruption, Impaction, Retention and Agenesis of the Permanent Second Molar

2007 ◽  
Vol 77 (5) ◽  
pp. 773-778 ◽  
Author(s):  
Lars Bondemark ◽  
Jola Tsiopa
Keyword(s):  
Early Diagnosis ◽  
Sample Size ◽  
Sample Size Calculation ◽  
Optimal Time ◽  
Second Molar ◽  
Ectopic Eruption ◽  
Delayed Eruption ◽  
Dental Records ◽  
The Times ◽  
The City

Abstract Objective: To elucidate the prevalence of ectopic eruption, impaction, and primary and secondary retention as well as agenesis of the permanent second molar (M2) among adolescents. Materials and Methods: After a sample size calculation, dental records, including radiographs, of 1543 patients (722 girls and 821 boys), from three clinics in the city of Malmoe, Sweden, were retrospectively analyzed. Series of annual records and radiographs were examined for all patients from 10 to 16 years of age and were carried out during 2004–2006. The prevalence of ectopic eruption, impaction, and primary and secondary retention as well as agenesis of M2s was registered in a standardized manner and according to preset definitions. In addition, the times of emergence of the M2s were recorded. Results: The prevalence of ectopic eruption of M2 was 1.5%, the prevalence of primary retention was 0.6%, and the prevalence of impaction was 0.2%. This means that the overall prevalence of eruption disturbances was 2.3%. In addition, the prevalence of agenesis was 0.8%. The prevalence of ectopic eruption was significantly higher in the mandible. Those patients with eruption disturbances and agenesis of M2 showed significantly delayed eruption of their other M2s compared to the individuals without any eruption disturbances. Conclusions: The prevalence of eruption disturbances was higher than reported earlier, and, even if the disturbances do not occur frequently, it is important to develop an early diagnosis in order to start the treatment at the optimal time.

Impact of repeated measures of joint space width on the sample size calculation: An application to hip osteoarthritis

2015 ◽  
Vol 82 (3) ◽  
pp. 172-176 ◽  
Author(s):  
Paul Ornetti ◽  
Laure Gossec ◽  
Davy Laroche ◽  
Christophe Combescure ◽  
Maxime Dougados ◽  
...  
Keyword(s):  
Sample Size ◽  
Repeated Measures ◽  
Sample Size Calculation ◽  
Joint Space Width ◽  
Hip Osteoarthritis ◽  
Joint Space ◽  
Space Width
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