# Is time always an independent variable?

#### VirginiaDee

##### New Member
Hi, i am struggling to decide whether to carry out a correlational or regression analysis. The experiment is designed to look at the relationship between time enduring pain and reported levels of depression. I am not manipulating the time. The participants will stop when it becomes painful, so they have total control of the time variable. Therefore, I can't work out if time, in this instance, is an independent or dependent variable. Any help would be much appreciated. Thanks

#### Miner

##### TS Contributor
This is not my area of expertise, but it seems to me that time might be a surrogate measurement for another quality, such as tolerance to pain.

#### hlsmith

##### Not a robit
What is the study questions you are trying to answer?

The term independent variable can refer to a person's ability to manipulate the variable. However, this day and age it gets used to describe any ol' term on the right-handside of the model.

#### noetsi

##### Fortran must die
It is hard to imagine anything that can change time, so making it a dependent variable makes little sense to me. Events can occur in time which is a different issue. I agree that you are not really measuring time here, you are measuring pain tolerance or something similar and using time as a proxy for that.

Regression is a correlational analysis. What methods are you actually considering.

#### CowboyBear

##### Super Moderator
Time can be an IV (e.g., time of exposure to a prime) or a DV (e.g., reaction times). Whether it's an IV or a DV in this case depends on your study and your definition of "IV". Some researchers only use the term "IV" when they've actually manipulated the variable. Others use it more broadly for a variable they hypothesise to be a cause.

What is your actual research question or hypothesis? Do you think that one of these variables has a causal effect on the other, or are you just interested in the relationship? If just looking at the relationship, you don't necessarily need to classify one as the IV and the other as the DV.