how would including a control group be useful in this experiment? responses it would provide a reference for the effects of random environmental factors. it would provide a reference for the effects of random environmental factors. it would provide a number against which percentages can be computed. it would provide a number against which percentages can be computed. it would provide a value for which the standard ph can be measured. it would provide a value for which the standard ph can be measured. it would provide a standard number to test for statistical uncertainty. it would provide a standard number to test for statistical uncertainty.