Manipulated and Responding Variables

Manipulated and Responding Variable Think of the manipulated and responding variable as something similar to cause and effect: the manipulated variable is the cause and the responding variable is the effect. Keep that in mind!

Variables There are 3 main types of variables: Manipulated Variable: The variable that is changed by the scientist; the ‘I control’ variable The MV (manipulated variable) is what you do! Responding Variable: The variable that might change because of what the scientist changes – what is being measured The RV (responding variable) is what happens. Controlled Variable: This is what stays the same in an experiment for each trial. It allows for a fair experiment

I scared my brother, and he screamed. Lets give it a try: I scared my brother, and he screamed. What did YOU do?

I scared my brother, and he screamed. Lets give it a try: I scared my brother, and he screamed. What did YOU do? YOU scared your brother. So, what happened because of your action?

I scared my brother, and he screamed. Lets give it a try: I scared my brother, and he screamed. This is the manipulated variable. You controlled or manipulated what happened: I scared my brother. This is the responding variable. This happened in response to what you did. My brother screamed.

I was so tired, I overslept. What did you control? What happened because of that?

I was so tired, I overslept. What did you control? You controlled how tired you were. What happened because of that? Because of how tired you were, you overslept.

I was so tired, I overslept. What did you control? You controlled how tired you were. Manipulated variable: How tired I was What happened because of that? Because of how tired you were, you overslept. Responding variable: I overslept. Cause: I was tired Effect: I overslept.

I played video games instead of studying for my science test, so I failed. What did you control or manipulate? What happened because of that?

I played video games instead of studying for my science test, so I failed. What did you control or manipulate? You controlled not studying. What happened because of that? You failed.

I played video games instead of studying for my science test, so I failed. What did you control or manipulate? You controlled not studying. Manipulated Variable: I played video games instead of studying. What happened because of that? You failed. Responding Variable: I failed by test.

 It looks like this

Plant Example You want to find out how light affects plant growth. Every day you measure the plant to see how much it has grown. Manipulated Variable: What is controlled or manipulated here? What acts on its own without you doing anything to it? Responding Variable: What happened because of the manipulated variable?

Plant Example You want to find out how light affects plant growth. Every day you measure the plant to see how much it has grown. Manipulated Variable: What is controlled or manipulated here? What acts on its own without you doing anything to it? The amount of sunlight is the manipulated variable. Responding Variable: What happened because of the manipulated variable? The plant growth is the responding variable.

Electromagnet Example An investigation was done with an electromagnetic system made from a battery and wire wrapped around a nail. The number of paper clips the electromagnet could pick up was measured. Manipulated Variable: What is controlled or manipulated here? What acts on its own without you doing anything to it? Responding Variable: What happened because of the manipulated variable?

Egg Example The higher the temperature of water, the faster an egg will boil. Manipulated Variable: What is controlled or manipulated here? What acts on its own without you doing anything to it? Responding Variable: What happened because of the manipulated variable?

Depth Example The temperature of water was measured at different depths of a pond. (depth= how deep a pond is). Manipulated Variable: What is controlled or manipulated here? What acts on its own without you doing anything to it? Responding Variable: What happened because of the manipulated variable?