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Monthly Archives: September 2017

Inferences for Population Proportions


Confidence Intervals for One Population Proportion Statisticicans often need to determine the proportion (percentage) of a population that has a specific attribute. Some examples are: the percentage of U.S. adults who have health insurance the percentage of cars in the United States that are imports the percentage of U.S. adults who favor stricter clean air […]

Nonparametric Methods of Estimating Survival Functions


Of the three survival functions, survivorship or its graphical presentation, the survival curve, is the most widely used. Examples include product-limit (PL) method of estimating the survivorship function by Kaplan and Meier, life-table analysis, relative survival rate, five-year surival rate, and corrected survival rate. Product-limit method is applicable to small, moderate, and large samples. However, […]

Several Major Distributions of Survival Function


Exponential Distribution The simplest and most important distribution in survival studies is the exponential distribution. In the late 1940s, researchers began to choose the exponential distribution to describe the life pattern of electronic systems. The exponential distribution has since continued to play a role in lifetime studies analogous to that of the normal distribution in […]