Skip to content

Category Archives: Clinical Trials

Linear Regression


The Regression Equation When analyzing data, it is essential to first construct a graph of the data. A scatterplot is a graph of data from two quantitative variables of a population. In a scatterplot, we use horizontal axis for the observations of one variable and a vertical axis for the observations of the other variable. […]

Inferences for Population Standard Deviations


Inferences for One Population Standard Deviation Suppose that we want to obtain information about a population standard deviation. If the population is small, we can often determine 𝜎 exactly by first taking a census and then computing 𝜎 from the population data. However, if the population is large, which is usually the case, a census is […]



If the information you need is not already available from a previous study, you might acquire it by conducting a census – that is, by obtaining information for the entire population of interest. However, conducting a census may be time consuming, costly, impractical, or even impossible. Two methods other than a census for obtaining information […]

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, […]

Why the Odds Ratio Can Be Used as an Estimate for Relative Risk in a Case-Control Study


The data in a case-control study represent two samples: The cases are drawn from a population of people who have the disease and the controls from a population of people who do not have the disease. The predictor variable (risk factor) is measured, and the results can be summarized in a 2 X 2 table […]