What is the purpose of control in a experiment?

Answer 1

A control experiment is a very important aspect of the scientific method.

Control experiments are used to minimize influences such as bias, genetic and biological variations, environmental changes, and random skewing.

In a controlled experiment one set of samples have been (or is believed to be) modified and the other set of samples are either expected to show no change (negative control) or expected to show a definite change (positive control).

Control experiments are especially useful in testing the effectiveness of new pharmaceuticals.

For example:

Let's say a company is developing an anti-smoking aid - which we'll call 'Cigstop' - and it has reached the human testing stage. To judge the effectiveness of the drug a control experiment would be administered to two groups.

The first group would receive Cigstop in its prescribed format, while the second group (the control) would receive a placebo believing it to be Cigstop.

Both groups are then instructed to attempt to quit smoking over a set period of time.

Once the experiment has concluded one can compare the two groups and determine the success rate of the drug. If the group that actually received Cigstop had a higher percentage of quitters than the control, then the drug shows an ability to assist someone in quitting smoking. Multiple control experiments showing the same results would verify the statistical probability of the drugs effectiveness.

Experiments such as the one above conducted without a control group could lead to unverified claims, and may be regarded as psuedo-science.

Answer 2

A control in a scientific experiment is an experiment designed to minimize the effects of variables other than the single independent variable. This increases the reliability of the results, often through a comparison between control measurements and the other measurements. Scientific controls are a part of the scientific method.

An example of an experimental control.

If you're testing the effectiveness of a headache medicine, you would give half of the individuals the actual medicine, and give the other half a placebo pill (an ineffectual pill, such as a sugar pill). The group that received the placebo pills are the control group, because they establish the baseline level of effectiveness that the medicine-treated group will be compared against. Without a control group, the experiment cannot determine whether the medicine-treated individuals feel beter than they would have if untreated.

Answer 3

The purpose of an experimental control is to provide a base-line result or set of results, from which you can compare the variables' effects against. Control groups are often included in medical or psychological experiments so that the results of an experiment are considered reliable and trustworthy.

For example:

A mystery-drug cure is being tested. One group of patients is given the drug and the other group is not. The group without the drug will be subject to all the same conditions that the other group are under, thereby seeking to eliminate any unforeseen effecting environmental factors. This makes it possible to compare, and therefore measure, the impact any drug would have.

As well as control groups, single- or double- blind testing may take place to eradicate experimenter bias and other unknown variables.

Answer 4

To have something to compare your results to. You can have controls that tell you if the results are different from normal conditions, or if the they are a result of the process/technique (rather than the substance/stimuli being tested). There are a wide variety of controls that should be deployed depending on the experiment being run.

Answer 5

A control exreriment allows you to see what the difference is from the variable changed in the experiment

Answer 6

its to be able to see what variables changed during the expeiment being preformed

Answer 7

To manipulate the experiment and study the outcome.

Answer 8

It is designed to make sure that only one factor is being changed, so you can be sure of its effect.