You want to make a scatterplot. Which variable would you use as the explanatory variable, and which as the response variable? Why? What would you expect to see in the scatterplot? Discuss the likely direction, form, and strength.
(a) Long-distance calls:time (minutes), cost (b) Lightning strikes: distance from lightning , time delay of the thunder © A street light: its apparent brightness, yourdistance from it (d) Cars:weight of car, age of owner
Explanatory variable, also known as independent variable (usually denoted by x) is essentially the variable you can freely control in the experiment, whereas the response variable, also known as the dependent variable (usually denoted by y) is the variable which is dependent on the independent variable. From the scatterplot, you expect to see a pattern and deduce an equation that will give you the relationship between x and y.
a) the cost varies with the duration of your call. Hence, duration is your explanatory variable whereas cost is the response variable. It is likely that the longer your call, the higher the cost.
b) the time delay varies with the distance from the lightning. Hence, distance is your explanatory variable whereas time delay is the response variable. It is likely the further away you are, the longer is takes for you to hear the lightning.
c) the brightness varies with your distance from the light. Hence, distance is the explanatory variable whereas the brightness is the response variable. It is likely that the further away you are, the less bright the light is.
d) this one is a little tricky. but I would assume that the older you are, the lighter you want your car to be. Hence, age is your explanatory variable and the weight of car is the response variable (meaning your choice of car varies according to what your age is). It is likely that the older you are, the lighter your car.