Basicmedical Key

What is It? We may be interested in the effect of several explanatory variables, x1, x2, …, xk, on a response variable, y. If we believe that these x’s may…

In Chapter 4 we showed how to create an empirical frequency distribution of the observed data. This contrasts with a theoretical probability distribution which is described by a mathema­tical model….

Rates In any longitudinal study (Chapter 12) investigating the occurrence of an event (such as death), we should take into account the fact that individuals are usually followed for different…

Clustered data conform to a hierarchical or nested structure in which, in its simplest form (the univariable two-level structure), the value of a single response variable is measured on a…

The Systematic Review What Is It? A systematic review1 is a formalized and stringent process of combining the information from all relevant studies (both published and unpublished) of the same…

Summarizing Data It is very difficult to have any ‘feeling’ for a set of numerical measurements unless we can summarize the data in a meaningful way. A diagram (Chapter 4)…

Summarizing Data If we are able to provide two summary measures of a continuous variable, one that gives an indication of the ‘average’ value and the other that describes the…

Statistical modelling includes the use of simple and multi­ple linear regression (Chapters 27–29), logistic regression (Chapter 30), Poisson regression (Chapter 31) and some methods that deal with survival data (Chapter…

Why Do We Sample? In statistics, a population represents the entire group of individuals in whom we are interested. Generally it is costly and labour-intensive to study the entire population…

What is Linear Regression? To investigate the relationship between two numerical variables, x and y, we measure the values of x and y on each of the n individuals in…