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The variable to be tested is the independent variable and you need to know this very early on as you design your experiment to achieve valid results. The independent variable is the one variable which you, as the experimenter, decide to vary. You will measure the dependent variable which changes as a result of altering the independent variable. You also have to identify and control all the other variables which could influence your measurements. These are the control variables.


I'm not entirely sure what you mean by this question. What usually happens first is we define the scientific question: this is the most important step in the process. Once you know the question, you can start designing experiments to answer the question, which may encompass several variables which you wish to measure or to control.

Hope that helps!


The variable tested will be known as the "dependent variable" this is the variable you will be measuring in an investigation. 

Really depends on what you are investigating can you give a context in which the question is being asked? 

Hope this helps

The variable can only be chosen AFTER the scientist has decided on the question (hypothesis) that is under investigation.

The broad topic might be factors affecting the growth rate in plants. A specific plant must be chosen and then a factor in order to answer the question.

The variable must then produce a set of results that will answer the question/hypothesis.

For example the question might be:

"Does light have an effect on growth rate of cress?" 

Having chosen the question the Scientist can choose to vary the light.

I hope that this helps.

Hi School18, could you give me the rest of the question please? Sounds as if that is one part of a bigger question.... in general, you determine the variable to be tested at the start of an experiment.

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