Showing 2 results for Research Methodology
Aa Haghdoost,
Volume 5, Issue 1 (6-2009)
Abstract
Sample size estimation is one of the crucial issues in the research methodology in medical sciences. It is an important issue for not only researchers but also readers of medical papers their frequent questions show how much they need to simple but accurate information.
This paper presents the basic concepts of sample size calculation, and simplifies complicated issues using concrete examples to clarify the concept of sample size estimation for none-professional readers in statistics. The paper starts with explaining the basic concepts of sample size calculation such as effect size, confidence interval and confidence coefficient, statistical errors, and assumptions in sample size calculation. Then, it presents the common formulae in the sample size calculation to estimate a mean, a proportion, to compare two means and to compare two proportions.
F Fakhri, S Eybpoosh, M Solaymani Dodaran ,
Volume 15, Issue 1 (5-2019)
Abstract
Background and Objectives: A considerable number of clinical trials are conducted in Iran each year. Not much is known about the characteristics of them, this study aimed to investigate key characteristics of Iranian clinical trials.
Methods: All clinical trial protocols registered in IRCT until November 2013 were selected. Text mining techniques were used to extract information from data that was mostly in the textual format. Stata software (v. 11) was used for both extraction and analysis.
Results: Totally 5049 trials where analyzed. Trials were in 40 different areas of medicine and their annual number was increasing. The sample size of registered trials was less than 70 in most trials and showed no significant improvement during the 5-year period (Median sample size= 64, inter quartile range (IQR) = 40-100). Phase III trials comprised 8.4% of the trials with a median sample size of 75 (IQR= 50-120). Of all phase III trials, 69% had a target sample size of less than 100. Most trials used randomization techniques (87.2%) but failed to use placebo (65.3%) and double/triple-blinding techniques (55.8%). The leading sponsors for 99.9% of trials were national bodies and 92.2% of the trials received public funds. Only 1% of the trials were exclusively sponsored by pharmaceutical companies.
Conclusion: The majority of clinical trials conducted in Iran are investigator-initiated and are funded by the public sector. The small sample size and failures in bias control observed in the majority of trials highlights the need for revising current policies of conducting trials in Iran.
