Independent and dependent variables, and constants, and standard of comparison?

Question

I am doing a pinto bean project where my question is asking whether or not soaking beans in water three days prior to planting them will increase their growth rate. I am confused about the ind. and dep. variables, constants, and standard of comparison. Please help.

Sorry If I didn't make myself clear. I myself believe the height of the plant is the dependent variable, but I don't know what the independent variable would be (amount of time, amount of water, etc.) Constants are factors that remain the same for both the experimental and control group I think. I think the Standard of comparison would be the exp. group and the control grp.

Answer 1

The independent variable is the thing that you are varying in order to see what the effect will be. In this case, it is whether you soak the beans or not.

The dependent variable is the thing that is affected by changes in the independent variable. In this case, it is the beans' growth rate.

The constants are all those things that you DON'T change. Presumably you will plant all the beans in identical soil, subject them to the same amount of sunlight and the same temperatures, provide the same amount of water and nutrients, etc., etc. These are the constants.

And your standard of comparison is whatever method you choose to measure growth rate. You don't state what that is. Is it the height of the plant after 2 weeks? The number of blossoms after a particular period of time? The number of days before the first leaves appear? (I'm making things up here.)

Perhaps a research scientist can give you a better definition of "standard of comparison," but I think it will have to do with how and when you measure the dependent variable (growth rate, in this case), and how you compare the plants using that measure.

Answer 2

I'm not sure how to place the answer in the context of your experiment but the independent variable is the thing you control and the dependent variable would be the thing you measure. On a graph the independent variable would go on the x - axis and dependant on the y axis. It's called the dependent variable because it's value is dependent on the value of thing you're controlling. As for the other two, well somebody else will have to answer those. I think the constant would be the relationship between the two variables, like for each time interval you soak the bean, the growth rate increases proportionally giving you a linear relationship but I'm not sure on that one, may want to double check, and see what other folks have to say.