Skip to content

Monthly Archives: December 2015

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 […]

Medical Statistics – Charting Continuous Metric Data


The Histogram A continuous metric variable can take a very large number of values, so it is usually impractical to plot them without first grouping the values. The grouped data is plotted using a frequency histogram, which has frequency plotted on the vertical axis and group size on the horizontal axis. A histogram looks like […]

Red Blood Cell Analytic Parameters


RBCs are defined by three quantitative values: the volume of packed red cells or hematocrit (Hct), the amount of hemoglobin (Hb), and the red cell concentration per unit volume. Three additional indices describing average qualitative characteristics of the red cell polupation are also collected. These are mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and […]

Medical Statistics – Types of Data


Categorical Data Nominal Categorical Data Nominal data are "nominal" because it usually relates to named things, such as occupation, blood type, or ethnicity. It is particularly not numeric. It is "categorical" because we allocate each value to a specific category. Therefore, for example, we allocate each M value to the category Male and each F […]