What could happen if you don't have a Control group within your experiment?

what could happen if you don't have a Control group within an experiment you are conducting?|||you'll have nothing to compare your results to. if your testing the effect of heat on the amount of bacteria in water and you just heat water and test it, but don't test a non heated water, then your results will mean nothing|||well say you are making a paint out of a new resin. Somebody says well the dry time is 2 hours - is that good or bad - you don't know, By putting a control in you can say, well the dry time is two hours 10 minutes and our control (our existing paint -or a competitor ) is 2 hours - so the dry time is marginally slower. In an experiment , a control is always desirable so one can measure a property against


known quantity.|||The purpose of an experiment is to test a hypothesis. In order to test said hypothesis, one must compare the effects of change on one variable in a system versus the system without changes. By doing so, a statement may be made whether or not the tested variable has an effect on the system.