Indian Journal of Dental ResearchIndian Journal of Dental ResearchIndian Journal of Dental Research
Indian Journal of Dental Research   Login   |  Users online:

Home Bookmark this page Print this page Email this page Small font sizeDefault font size Increase font size         


REVIEW ARTICLE Table of Contents   
Year : 2012  |  Volume : 23  |  Issue : 5  |  Page : 660-664
Concepts in sample size determination

Department of Oral and Maxillofacial Pathology, Ragas Dental College and Hospital, 2/102 East Coast Road, Uthandi, Chennai, India

Correspondence Address:
Umadevi K Rao
Department of Oral and Maxillofacial Pathology, Ragas Dental College and Hospital, 2/102 East Coast Road, Uthandi, Chennai
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0970-9290.107385

Rights and Permissions

Investigators involved in clinical, epidemiological or translational research, have the drive to publish their results so that they can extrapolate their findings to the population. This begins with the preliminary step of deciding the topic to be studied, the subjects and the type of study design. In this context, the researcher must determine how many subjects would be required for the proposed study. Thus, the number of individuals to be included in the study, i.e., the sample size is an important consideration in the design of many clinical studies. The sample size determination should be based on the difference in the outcome between the two groups studied as in an analytical study, as well as on the accepted p value for statistical significance and the required statistical power to test a hypothesis. The accepted risk of type I error or alpha value, which by convention is set at the 0.05 level in biomedical research defines the cutoff point at which the p value obtained in the study is judged as significant or not. The power in clinical research is the likelihood of finding a statistically significant result when it exists and is typically set to >80%. This is necessary since the most rigorously executed studies may fail to answer the research question if the sample size is too small. Alternatively, a study with too large a sample size will be difficult and will result in waste of time and resources. Thus, the goal of sample size planning is to estimate an appropriate number of subjects for a given study design. This article describes the concepts in estimating the sample size.

Print this article     Email this article

 Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
  Citation Manager
 Access Statistics
  Reader Comments
  Email Alert *
  Add to My List *

 Article Access Statistics
    PDF Downloaded458    
    Comments [Add]    
    Cited by others 5    

Recommend this journal