Saturday, August 21, 2010

In an experiment what is the independent variable,dependent variable and controlled variable?

my experiment is if i heat an equal amount of cold and hot water which will boil first can anyone help me out on naming the variables in this





thanks in advanceIn an experiment what is the independent variable,dependent variable and controlled variable?
Independent Variable: Hot and Cold Water


Dependent Variable: Temperature of water after time length of heating


Controlled Variables: Same heating method, at same temperature, same containers











In the design of experiments, independent variables are those whose values are controlled or selected by the person experimenting (experimenter) to determine its relationship to an observed phenomenon (the dependent variable). In such an experiment, an attempt is made to find evidence that the values of the independent variable determine the values of the dependent variable (that which is being measured). The independent variable can be changed as required, and its values do not represent a problem requiring explanation in an analysis, but are taken simply as given. The dependent variable on the other hand, usually cannot be directly controlled.





Controlled variables are also important to identify in experiments. They are the variables that are kept constant to prevent their influence on the effect of the independent variable on the dependent. Every experiment has a controlling variable, and it is necessary to not change it, or the results of the experiment won't be valid.





In summary:





* Independent variables answer the question ';What do I change?';.


* Dependent variables answer the question ';What do I observe?';.


* Controlled variables answer the question ';What do I keep the same?';.





Examples





* If one were to measure the influence of different quantities of fertilizer on plant growth, the independent variable would be the amount of fertilizer used (the changing factor of the experiment). The dependent variables would be the growth in height and/or mass of the plant (the factors that are influenced in the experiment) and the controlled variables would be the type of plant, the type of fertilizer, the amount of sunlight the plant gets, the size of the pots, etc. (the factors that would otherwise influence the dependent variable if they were not controlled).





* In a study of how different doses of a drug affect the severity of symptoms, a researcher could compare the frequency and intensity of symptoms (the dependent variables) when different doses (the independent variable) are administered, and attempt to draw a conclusion.





* In measuring the acceleration of a vehicle, time is usually the independent variable and speed is the dependent variable. This is because when taking measurements, times are usually predetermined, and the resulting speed of the vehicle is recorded at those times. As far as the experiment is concerned, the speed is dependent on the time. Since the decision is made to measure the speed at certain times, time is the independent variable.





* In measuring the amount of color removed from beetroot samples at different temperatures, the dependent variable would be the amount of pigment removed, because it is depending on the temperature (which is the independent variable).





* In sociology, in measuring the effect of education on income or wealth, the dependent variable could be a level of income or wealth measured in monetary units (United States Dollars for example), and an independent variable could be the education level of the individual(s) who compose(s) the household (i.e. academic degrees).In an experiment what is the independent variable,dependent variable and controlled variable?
hmm i did this i dont remember which ones which but we had to boil yeast aww buddy that crap smelt like old similac YUCK Titty milK LOL but it was cool we had to boil a already cold 1 and a room temp one and a already hot 1
control : room temperature water


dependant v: how long it takes the water to boil


ind variable: the starting temps of water





i think... not sure.
independent: heating of the water


dependent: which boils first


controlled: amount of water

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