If you can find a way to turn an independent variable cost into a dependent variable cost, more power to you. Your business might be able to count itself as one of the successful ones.

This “potentially causal variable” is called, traditionally, the “independent variable.” With the current example, that would be the coffee.

Learn about planning experiments and variables when working scientifically with these interactive learning resources for KS2 Science students aged 7-11 from BBC Bitesize.

For example, a scientist could ask “How does the wingspan on a paper airplane affect how far it can fly?” In this case, the independent variable, what is being tested, is the wingspan; and the ...