It's the week before prom, and disaster has struck: Your best friend accidentally bought the same dress as you, and now you only have a couple of days left to track down a new one.
You're scrolling through websites and making frantic calls to every dress store in the county. You begin to panic as store after store tells you that they have sold out already. Tears stream down your cheeks as you stare longingly at a black and white polaroid photograph of your date. With only a shred of hope left in your barely beating heart, you stumble upon the Macy's Spring Clearance Sale.
You desperately look for the dress of your dreams, but all that's left is a single sleeveless chiffon gown, available in only four colors: Poppin' Purple, Zazzy Azure, Ostentatious Orange, and Red. It all comes down to one defining factor: which color will turn the most heads when you strut into the old gymnasium with your hot date on your arm?
There's one way to find out, and that's through a well-devised experiment.
Research is a systematic investigation to solve problems. Psychologists sometimes use experiments to create controlled environments for establishing causation. When carrying out your experiment, everything is driven by a hypothesis, which is an educated guess about what might happen. For example, a hypothesis for our prom dress experiment might be that wearing the Red dress will turn the most heads at the dance because red is found to enhance attraction.
Clearly, one thing will cause a change in the other thing. When referring to these two "things," we use the terms independent and dependent variable. As you try on each color of the dress, you are manipulating the independent variable because you are in control of the colors you test. Later on, you will be counting the number of double takes you get, boogying throughout the night. You'll have to go to a lot of proms, but the number you get from testing out each dress color is your dependent variable because this number depends on your independent variable.
Everything sounds perfect, right? WRONG! You can't be sure of your results if they're affected by confounding variables, which are external factors that might mess up your causal relationship. You can't fairly judge Ostentatious Orange against Poppin' Purple if your hair looks different and you're wearing different shoes between trials! It's going to be a stressful night, because in order to make sure all of the other variables are constant, you'll have to wear all four dresses on the same night and change in the bathroom between slow dances.
Finally, the day arrives and you successfully carry out your experiment. While your date thought you looked fabulous in every color, you were able to observe that one of the dresses stood out the most on the dance floor...
Surprise, surprise: It was Zazzy Azure!
