Identifying Independent and Dependent Variables, and Study Designs

 

Instructions: For each research description below, identify the independent variable, the dependent variable, and the type of study (lab experiment, naturalistic observation, survey, or case study).

 

  1. A researcher hypothesizes that blondes really do have more fun.  To test this hypothesis, she interviews a natural brunette who has recently become a blonde to determine if there is any change in the amount of fun she has.

 

Independent variable: ________________________________

Dependent variable: ________________________________

Type of study: ________________________________

 

  1. A developmental psychologist is testing the hypothesis that children in first grade know more words in the English language than children in Kindergarten.  To test this, she sits in on two classes (one first grade, the other Kindergarten) and counts the average number of words children in each class speak.  She then compares the counts.

 

Independent variable: ________________________________

Dependent variable: ________________________________

Type of study: ________________________________

 

  1. A clinical psychologist hypothesizes that people who have been diagnosed as having major depression will be more likely to also be diagnosed with an anxiety disorder than will people who have not been diagnosed with major depression. To test this, he gives a survey to 100 people being treated for depression and 100 people with no known mental disorder.  The survey asks them to report whether or not they have been diagnosed as having an anxiety disorder.

 

Independent variable: ________________________________

Dependent variable: ________________________________

Type of study: ________________________________

 

 

  1. A pharmacologist is testing whether a new anti-anxiety medication, Moodcor, will cause people to gain weight.  To test this, she gives 100 people Moodcor for one month and 100 people a placebo drug.  At the end of the month, she monitors any weight gain.

 

Independent variable: ________________________________

Dependent variable: ________________________________

Type of study: ________________________________

 

 

  1. A developmental psychologist believes that if children successfully lie to their friends, they will be more likely to try lying to their parents.  To test this hypothesis, he asks 50 children to report how many times in the last month they have lied to their friends, and whether they were successful.  He then asks them how many times they have lied to their parents.

 

Independent variable: ________________________________

Dependent variable: ________________________________

Type of study: ________________________________

 

  1. A personality psychologist believes that people who are more aggressive are more likely to purchase sports coupes than people who are less aggressive.  To test this, he visits local car dealerships and asks car shoppers to complete an aggression survey.  Then, he observes what types of cars they purchase (sports coupe, sedan, SUV, or pickup). 

 

Independent variable: ________________________________

Dependent variable: ________________________________

Type of study: ________________________________

 

  1. A clinical psychologist hypothesizes that listening to an inspirational tape will lead one to be in a better mood.  To test this, she has 50 people listen to an hour-long inspirational tape.  Another 50 listen to white noise for an hour.  She then has them rate their mood on a 10-point scale.

 

Independent variable: ________________________________

Dependent variable: ________________________________

Type of study: ________________________________

 

  1. A clinical psychologist is testing his theory that people who experienced a brain injury are developmentally delayed to the age at which they experienced the injury (for instance, if one has a brain injury at the age of 10, that person will always act like they are 10).  To test this, he conducts developmental interviews with two people who experienced a brain injury at two different ages (one was 3 and one was 20).

 

Independent variable: ________________________________

Dependent variable: ________________________________

Type of study: ________________________________

 

Answers (With Explanations)

 

1.                  IV: Hair colour

DV: Amount of fun

Type of study: Case study, because one person is being interviewed.

 

2.                  IV: Age (first grade or Kindergarten)

DV: Number of words known

Type of study: Naturalistic observation. She is sitting in on classrooms and observing what the kids are doing without their knowledge.

 

3.                  IV: Whether one has depression or not

DV: Presence of anxiety disorder

Type of study: Survey

 

4.                  IV: Getting the medication

DV: Weight gain

Type of study: Lab experiment. This is because the researcher is the one giving the people the medication or the placebo drug. That is, the researcher is manipulating or controlling the presence of the IV.

 

5.                  IV: Successfully lying to friends

DV: Lying to parents

Type of study: This is a survey. The key here is that there are a lot of people in the study (50 children). This is NOT a case study because there are too many people. Case studies only contain a handful of participants.

 

6.                  IV: Aggressiveness

DV: Whether a sports coupe is purchased

Type of study:  This is a tricky one. It is actually a combination of a survey AND a naturalistic observation. This is because the aggressiveness scores are obtained with a survey. But, information on the type of car purchased is obtained by watching what the participants do.  This study demonstrates that you can often use more than one method simultaneously!

 

7.                  IV: Whether one listens to the inspirational tape, or the white noise

DV: Mood

Type of study: Lab experiment. This is a lab experiment because, again, the researcher is manipulating who gets the IV. That is, she is determining whether the participants listen to the tape, or the white noise.

 

8.                  IV: Brain injury

DV: Age one is developmentally delayed

Type of study: Case study. Another case study…this one with two participants. If the study only contains a few people (say, about 5 or less), chances are it is a case study!

 

 

 

This worksheet was found at http://www.spsp.org/student/intro/assign/variables.doc