slide1 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
SAMPLE SIZE DETERMINATION PowerPoint Presentation
Download Presentation
SAMPLE SIZE DETERMINATION

Loading in 2 Seconds...

play fullscreen
1 / 22

SAMPLE SIZE DETERMINATION - PowerPoint PPT Presentation


  • 187 Views
  • Uploaded on

SAMPLE SIZE DETERMINATION . Dr. M. H. Rahbar Professor of Biostatistics Department of Epidemiology Director, Data Coordinating Center College of Human Medicine Michigan State University. Important Statistical Terms.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'SAMPLE SIZE DETERMINATION' - anila


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

SAMPLE SIZE DETERMINATION

Dr. M. H. Rahbar

Professor of Biostatistics

Department of Epidemiology

Director, Data Coordinating Center

College of Human Medicine

Michigan State University

important statistical terms
Important Statistical Terms
  • Population:A set which includes all measurements of interest to the researcher
  • Sample: Any subset of the population
  • Parameter of interest: The characteristic of interest to the researcher in the population is called a parameter
inferential statistics
INFERENTIAL STATISTICS
  • Estimation: This includes point and interval estimation of certain characteristics in the population(s). (e.g., Means, proportions)
  • Testing Hypothesis about population parameter(s) based on the information contained in the sample(s)
slide4

Confidence Intervals for population Mean, µ

95% C.I. For , when n30, is

slide6

Confidence Intervals for Prevalence of a disease in a population (or Proportion P)95% C.I. For Prevalence P is

slide12

QUESTION: Do persons with the disease have higher blood levels of “factor X” than those without disease?

slide14

Risk Factors for Myocardial Infarction (MI)

Null Hypothesis: There is no association between hypertension and Myocardial Infarction, or P1=P2, where P1 and P2 are the prevalence of hypertension among cases and controls respectively.

Alternative Hypothesis: There is an association between hypertension and Myocardial Infarction, P1P2.

sample size determination for a 1 1 case control ratio
Sample size determination for a 1:1 case control Ratio
  • A study with 250 cases, 250 controls will safely detect risk factors with an odds ratio of three or more, unless they are extremely common or extremely uncommon
  • We have a good chance of detecting factors with an odds ratio of two to three, providing their prevalence in the source population is between about 20% and 70%.
sample size determination for a 1 k case control ratio
Sample size determination for a 1: k case control Ratio
  • When it is difficult to recruit sufficient cases during the intended study period, the power may be increased by selecting more than one control per case.
  • For details you may want to see standard Epidemiology textbooks.