This guide breaks down the basics of horizontal and vertical lines with clear examples, practical applications, and simple diagrams so that remembering the difference becomes second nature.

A simple random sample is a subset of a statistical population where each member of the population is equally likely to be chosen.

Pareto analysis states that 80% of a project’s results are due to 20% of the inputs, and 80% of problems can be traced to 20% of the causes.