Bivariate Data

We wish to emphasize that the data sets presented so far are associated with a single random variable. This means that each sample refers to a single, specific population or population characteristic. The technical name for such data is univariate. Data which derives from two separate populations or population characteristics is called bivariate.

Categorical Data

Statistics is often introduced using quantitative data such as height, weight, waiting time, etc. But there is a wide, wide world of very important data of a different type; qualitative or categorical data. As the name suggests, categorical data is expressed, as a random variable, in terms of categories or cells; two or more information[…]


Testing Categorical Data

Introduction Chi-Square Tests are generally applied to categorical data. Yet the Chi-square distribution is a continuous random variable. How can this be ? The answer may be found in the history of statistical methods. Just as de Moivre and Laplace sought for and found the normal approximation to the binomial, Karl Pearson sought for and[…]