NOTES
Here's what I hope is an illuminating chart - We have an independent variable - like the kind of gas being put into a balloon - we can control the properties of the balloon by changing this variable. Then there are various quantities that vary in response to changes in the independent variable - like the tendency to fly away, and the tendency to have a string. The dependent quantity are correlated, not because one is controlling the other, but because the independent variable is controlling them both.