This outstanding book by John MacInnes starts asking the question: "why do we need variables?" and it immediately contextualises this brilliant introductory text within daily life and the central importance of thinking about how we measure, compare, contrast and explore all things and discover the landscape of rigorous research.
Not sufficient for my teaching purposes
excellent little book that every research student should own
Because even students in advanced research methods courses are often confused about the different definitions and types of variables, this booklet is an excellent resource for undergraduates at all levels.