Control variable - wikipedia Control variable Not to be confused with Control variable ( programming ) or Optimal control. See also : Control variable ( statistics ) The control variable ( or scientific constant ) in scientific experimentation is the experimental element which is constant and unchanged throughout the course of the investigation. The control variable strongly influences experimental results, and it is held constant during the experiment in order to test the relative relationship of the dependent and independent variables. The control variable itself is not of primary interest to the experimenter. Contents 1 Usage 2 Experimental examples 3 References 4 External links Usage A variable in an experiment which is held constant in order to assess the relationship between multiple variables, is the control variable. A control variable is the one element that is not changed throughout an experiment, because its unchanging state allows the relationship between the other variables being tested to be better understood. Essentially, a control variable is what is kept the same throughout the experiment, and it is not of primary concern in the experimental outcome. Any change in a control variable in an experiment would invalidate the correlation of dependent variables ( DV ) to the independent variable ( IV ), thus skewing the results. Experimental examples In any system existing in a natural state, many variables may be interdependent, with each affecting the other. Scientific experiments tests the relationship of an IV -- that element which is manipulated by the experimenter -- to the DV -- that element affected by the manipulation of the IV. Any additional independent variable can be a control variable. Take, for example, the combined gas law, which is stated mathematically as : P V T = k ( displaystyle qquad ( \frac ( PV ) ( T ) ) = k ) where : P is the pressure V is the volume T is the thermodynamic temperature measured in kelvins k is a constant ( with units of energy divided by temperature ). which shows that the ratio between the pressure - volume product and the temperature of a system remains constant. In an experimental verification of one part of the combined gas law, Boyle 's law, ( P * V = T ), where Pressure, Temperature, and Volume are all variables, to test the resultant changes to any of these variables requires at least one to be kept constant. This is in order to see comparable experimental results in the remaining variables. If Volume is made the control variable and it is not allowed to change throughout the course of the experiment, the relationship between dependent variables, Pressure and Temperature, can quickly be established by changing the value for one or the other. For instance, if the Pressure is raised then the Temperature must increase. If, however, Temperature is made the control variable and it is not allowed to change throughout the course of the experiment, the relationship between the dependent variables, Pressure and Volume, can quickly be established by changing the value for one or the other. For instance, the Pressure is raised then the Volume must decrease. References ^ Jump up to : control variable ; Business Dictionary online ; retrieved September 2015. ^ Jump up to : Definitions ; Science Buddies -- Science Fair Projects. ^ Jump up to : PPT Download ; ( 1 ) External links Definitions ; Science Buddies -- Science Fair Projects. Retrieved from `` https://en.wikipedia.org/w/index.php?title=Control_variable&oldid=866370807 '' Categories : Science experiments Variables ( mathematics ) Talk Contents About Wikipedia Català فارسی 한국어 Simple English 中文 Edit links This page was last edited on 29 October 2018, at 23 : 01 ( UTC ). About Wikipedia

Question: what is the purpose of the control variable
Answer: in order to test the relative relationship of the dependent and independent variables