When carrying out the experiment, care has to be taken that other variables that affect the rate of reaction, such as concentration of reactants, are kept constant. These are control variables.

The use of instrumental variables regression in political science has evolved from an obscure technique to a staple of the political science tool kit. Yet the surge of interest in the instrumental ...

Variables are explained through the story of a squirrel and where his nuts are buried.

This paper describes an investigation of emissions from an engine featuring variable valve timing, a swirlcontrol valve and exhaust gas recirculation. Design of experiments has been used to model the ...