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 experiment has a control with no insect in order to compare results. A wide variety of living organisms can be investigated including insects, woodlice, maggots or germinating peas.

(1) In 1973 an outdoor experiment was begun to test the role of interference in determining the relative abundances of four species which grow together in roadside Arrhenatheretum, a community which ...

The attitudinal and behavioral effects of being promoted and being rejected for promotion were examined in a quasi experiment conducted at an international bank in Hong Kong. Promoted tellers who had ...