Friday, January 27, 2012

Independent variable?

what is the independent variable in a science experiment??? and what is the dependent and the controll???Independent variable?
dependant varabile: A dependent variable is what you measure in the experiment and what is affected during the experiment. The dependent variable responds to the independent variable. It is called dependent because it "depends" on the independent variable. In a scientific experiment, you cannot have a dependent variable without an independent variable.

An independent variable is a factor that can be varied or manipulated in an experiment (e.g. time, temperature, concentration, etc). It is usually what will affect the dependent variable.

There are two types of independent variables, which are often treated differently in statistical analyses: (1) quantitative variables that differ in amounts or scale and can be ordered (e.g. weight, temperature, time). (2) qualitative variables which differ in "types" and can not be ordered (e.g. gender, species, method). By convention when graphing data, the independent variable is plotted along the horizontal X-axis with the dependent variable on the vertical Y-axis.

control: A control in an experiment is a group, sample, test, etc. that is used in comparison to the group, sample, test, etc. that the experiment is actually done for. Controls can also be samples in which the expected value is known. This is the part of the expirement that does not change.

Examples: In clinical trials the control group gets the placebo. In genetic experiments the control is usually the wild-type organism.

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