The analysis of time-to-event data is of paramount importance in clinical and epidemiological research. The clinical research in the areas of oxidative stress and biological consequences of aging and alterations of immune function and metabolism commonly demands the application of specific statistical techniques aimed at investigating the strength of the relationship between certain risk factors (for example, oxidized low density lipoprotein) and adverse outcomes (for example, death and cardiovascular events).
In this paper, we describe the mathematical background of this technique and the concept of censoring (right censoring, interval censoring, and left censoring) and report some examples demonstrating how to construct a Kaplan-Meier survival curve and how to apply this method to provide an answer to specific research questions. Among these, the Kaplan-Meier analysis is the most used one in both observational and interventional studies. Survival data require adequate methods of analyses. Indeed, time-to-event analysis is one of the most important methodologies used in clinical and epidemiological research to address etiological and prognostic hypotheses. Studies performed in the field of oxidative medicine and cellular longevity frequently focus on the association between biomarkers of cellular and molecular mechanisms of oxidative stress as well as of aging, immune function, and vascular biology with specific time to event data, such as mortality and organ failure. Loyola University's Center for Science Education has a discussion of the dividing method in this.
Honolulu Community College has a description of the area method and a page on graphs as a part of a Physical Science course.If you would like to know more about best-fit lines, you can use the links below to read more about them References and resources If you think you have a handle on the construction of a best fit line, click on this bar to try some practice problems with worked answers! Next steps - Some practice problems I am ready to PRACTICE! In the introductory geosciences, we use them for:
There are many instances in the geosciences where scientists use a best fit line.
You can also download and print a single sheet for constructing a best fit line with the area method (Acrobat (PDF) PRIVATE FILE 33kB Sep10 08) or the dividing method (Acrobat (PDF) PRIVATE FILE 34kB Sep10 08).