Independent, dependent variables, control group, experimental group? what?!?

Dependent Variable - A measurable phenomenon that changes in response to an independent variable--the EFFECT in a Cause and Effect Relationship. Independent Variable - Any quantity or attribute deliberately manipulated to invoke a change in the dependent variable--the CAUSE in a Cause and Effect Relationship. Control group - Individuals (control subjects) that are not exposed to the independent variable. Every member of the control group is not subjected to the experimental manipulation. Experimental group - Individuals (test subjects) who are exposed to the independent variable. By measuring whether there is a statistically significant difference between the experimental and control groups when measuring the dependent variable, a scientist is able to test an experimental hypothesis. If there is a significant difference, the research hypothesis is supported. For example, if you wanted to test the research hypothesis that an aspirin a day reduces the likelihood of a heart attack, then aspirin use would be the independent variable. The experimental group would take an aspirin each day, while the control group would take a placebo, such as a sugar pill, that resembles an aspirin but has none of the effects attributed to aspirin. After a few months or years of pill-taking, the number of heart attacks would be measured as the dependent variable. If the aspirin-takers (experimental group) had a significantly smaller number of heart attacks than the placebo-takers (control group), then the research hypothesis (aspirin-taking reduces heart attacks) would be supported.

Dependent variables depend on the independent variable. Like if the variables are temperature vs. pH, the pH of something depends on what the temperature is, not the other way around. The control group is used so you'll have something to compare the experimental group to. Like if you're experiment is whether or not some mutant organism you created can survive better under UV light (the experiment). You'd have to put that organism under regular white light (the control) to see if there is a difference.

Variable- What could be changed. Only one will be changed in an experiment Independent variable - You (the experimenter) can change these. Dependent variable - What changes as a result of changes to independent variables. Control group - A group where you control all variables. Should have known results. Experimental group - A group where you change one variable. Difference from control group is assumed to be from the change of the variable. Example: Testing effect of sunlight on growing plants. Amount of sunlight received would be the independent variable, and would be different between the control group and experimental group. Amount of water received, type of soil, type of plant would be other independent variables, but should be the same between the two groups. Dependent variables would be things like root length, plant height, number of leaves grown, mass gained... ways to measure the growth of the plant.