Friday, May 14, 2010

How are control variables and expermental variables used in scientific investigations?

Data is collected for various values of the experimental variable while the controlable variables are kept constant.





In chemical and some biological laboratory tests where one wishes to quantify a particular element or compound in a sample, the procedure calls for using a known standard and/or a control. Sometimes there is a high contol and a low control, these being samples of carefully established known values.





Where results are to be primarily qualitative, a positive control and a negative control are often used.How are control variables and expermental variables used in scientific investigations?
Simple logic prevails. Isolate the condition you want to test, and eliminate extraneous influence from all other variables. In some experiments they use a ';double blind'; strategy to isolate the desired response. However, you need to test a large enough population of outcomes for the result to be statistically significant. The sample size is determined by the mathematical laws of probability and statistics.

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