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Category Archives: Epidemiology

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 […]

Stage, Expression, and Causal Model of Diseases


Natural History of Disease Stage of Disease The natural history of disease refers to the progression of a disease in an individual over time. This includes all relevant phenomena from before initiation of the disease (the stage of susceptibility) until its resolution. In the period following exposure to the causal factor, the individual enters a […]

Basic Concepts in Epidemiology


Risk Risk, sometimes also referred to as cumulative incidence, is an indicator of the proportion of persons within a specified population who develop the outcome of interest (all persons under consideration must be free of the outcome of interest at the beginning), within a defined time period. R = New cases / Persons at risk […]