Biostatistics Confidence Inte

Initial Post:

Find an example of a 95% confidence interval in a research article (include the link to the article). Give an interpretation of the confidence interval. What question is the confidence interval answering? Give a description of the sample that is used in the research. Be thorough in both your reporting of the confidence interval and your description of the sample and give a citation for the article. You can search for research articles using Google Scholar.

Response Posts:

Read the posts of other learners and respond to at least 2 other learners. Your responses are expected to be substantive in nature and reference the assigned readings, as well as other theoretical, empirical, or professional literature to support your views and writings. In your response, do at least one of the following:

  • Provide a reason why it may be beneficial to change the confidence level.
  • State whether you agree with the interpretation and why.

Discussion 1:

Article: Age at smoking onset and it’s effect on smoking cessation (Links to an external site.)

The researchers used a probability sample to obtain a sample of 1710 males who lived in Philadelphia between 1985-1987. This means that n=1710 for the sample studied. For this study, the research hypothesis was that the age when a person starts smoking has an effect on whether or not they successfully quit smoking later. The null hypothesis would be that age does not have an effect on successful smoking cessation.

The article stated that “Men who started smoking before 16 years of age had an odds ratio of 2.1 (95% confidence interval: 1.4–3.0) for not quitting smoking compared to those who started at a later age” This means that the researchers could state with a 95% certainty that the odds ratio for men who started smoking before age 16 falls between 1.4 and 3.0.

Discussion 2:

The sample of the study is a group of 436 mothers with occurrent cases of neural tube defects (NTD) and 2165 mothers with other major malformations. The objective of the study, is to see if women who take 4 mg of folic acid before and in early pregnancy will help reduce the risk of recurrent NTDs. By taking this vitamin the goal is to reduce the risks by 76%. The folic acid dose of 0.4 mg is contained in most over the counter multivitamins. By taking the most common dose of 0.4 mg the relative risk estimate was 0.3 (95% confidence interval, 0.1 to 0.6). The interpretation of this confidence interval is that we are 95% confident that the proportion of women, who take 0.4mg before and in early stages of pregnancy in the population is between 0.1 to 0.6. The outcome of the study proposes that if you take 0.4 mg of folic acid it will reduce the risk of occurrent NTDs by roughly 60%.

Werler MM, Shapiro S, Mitchell AA. Periconceptional Folic Acid Exposure and Risk of Occurrent Neural Tube Defects. JAMA. 1993;269(10):1257–1261. doi:10.1001/jama.1993.03500100055027

Link to Article: 

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