Identifying Independent and Dependent Variables, and Study Designs Answers (Experimentation Packet Answers)

Part 1

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: hair color
Dependent variable: the amount of fun
Type of study: case study; because one person is being interviewed.
   
2. 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: Age (first grade or Kindergarten)
Dependent variable: 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. 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: Whether one has depression or not
Dependent variable: Presence of anxiety disorder

Type of study: Survey

4. 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: Getting the medication 
Dependent variable: 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. A clinical psychologist believes that a particular drug will increase students’ IQ. To test this hypothesis, he measures IQ, gives them a drug and measures their IQ again.
 
Hypothesis #1: drug will not increase students’ IQ.
Hypothesis #2: drug will increase students’ IQ.
Type #1: You say the drug does increase IQ when it actually doesn’t

6.  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). 

Hypothesis #1: people who are more aggressive are NOT more likely to purchase
sports coupes than people who are less aggressive
Hypothesis #2: people who are more aggressive are more likely to purchase sports
coupes than people who are less aggressive
Type #1: you say that aggressive = sports cars when they are really more
likely to buy them.


7.  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).

Hypothesis #1: listening to an inspirational tape will not lead one to be in a better
mood.
Hypothesis #2: : listening to an inspirational tape will lead one to be in a better mood.
Type #1: you say that the tape does lead to mood increase when it actually
doesn’t

Type #2: you say that the tape doesn’t lead to mood increase but it actually does.

Part 2 

1. Of 100 individuals with moderate depression, 50 receive 8 weeks of a new cognitive-behavioral therapy, while the other 50 are placed on a waiting list for 8 weeks. After 8 weeks all 100 are given psychological tests to assess their level of depression.

Independent Variable: cognitive therapy

Dependent Variable: level of depression

Experimental group: those who get the therapy

Control group: those on the waiting list       

2. A biopsychologist is studying the effects of anabolic steroids on the aggressive behavior of female rats. 24 female rats receive daily injections of a placebo (fake drug), while 24 others receive daily injections of the steroid. Round-the-clock videotapes of the communal cages of all rats allow all aggressive encounters to be counted and timed.

Independent Variable: steroid

Dependent Variable: aggressive behavior

Experimental group: rats that get steroid