Chapter 3

Type I Error

A false positive result from a statistical inference process, inwhich researchers concluded that there is an effect on the population when there really is none.

Type II Error

A miss in the statistical inference process. In which researchers concluded that there is no effect in the population when there really is one.

Conceptual Definitions

A researchers definition of a variable at the theoretical level.

Margin of Error Estimate

A statistical figure, based on sample size for a poll, that indicates where the true value in the population probably lies.

Correlational Study

A study that measures two or more variables.

Manipulated Variable

A variable a researcher controls, usually by assigning participants to the different levels of that variable. (Ex: a researcher might give some participants 10 mg of a medication, and others 20mg. Or A researcher might assign some people to take a test in a room with many other people, and assign other people to take the test alone.

What kind of a claim is the following headline making? "You Gotta Have Friends? Most Have Just Two True Pals." A. frequency claim B. association claim C. causal claim D. anecdotal claim

A. Frequency Claim Because: Frequency Claims — This headline is claiming that most people have two friends.

Which of the following questions addresses construct validity? A. How well has the researcher measured or manipulated the variables in the study? B. What is the effect size? C. To what populations, settings, and times can we generalize this claim? D. Does the study control for alternative explanations?

A. How well has the researcher measured or manipulated the variables in the study? Because: Interrogating the Three Claims Using the Four Big Validities — Interrogating construct validity means evaluating how well the variables were measured or manipulated in the study.

Which of the following is an example of a causal claim? A. Ice applied to a twisted ankle prevents swelling. B. Women re-gift at a 50 percent greater rate than men. C. Sweetened drinks are linked to depression risk. D. Folic acid is tied to better toddler talk.

A. Ice applied to a twisted ankle prevents swelling. Because: ausal Claims — "Is linked" and "tied to" are associative claims. "50 percent greater rate" is a frequency claim.

In most experiments, tradeoffs are made between validities because it is not possible to achieve all four at once. What is the most common tradeoff? A. Increased internal validity results in decreased external validity. B. Increased construct validity results in decreased statistical validity. C. statistical validity results in decreased internal validity. D. Increased external validity results in decreased statistical validity.

A. Increased internal validity results in decreased external validity. Because: Producers of Information: Prioritizing Validities — Experiments are studies designed to show causality, which depends on internal validity. In order to emphasize causality, the generalizability of the results is reduced.

Reading the news on the Internet, Johan comes across the headline, "When Stress is Increased, Men Rush Ahead, Women More Cautious." (This headline is based on a study conducted by Lighthall et al., 2011.) In this study, men and women were asked to perform a decision task as many times as possible in a set period, in either a stressed or unstressed condition. In the unstressed condition, men and women performed similarly. However, in the stressed condition, the number of decision tasks performed by men increased while the number performed by women decreased. Which of the following is a constant in this study? A. the amount of time to perform the decision task B. sex of the participants C. the amount of stress D. number of decision tasks performed

A. The amount of time to perform the decision task Because: Constant — The time period is set. All the other choices vary in the study.

Which of the following criteria is NOT required for a causal claim? A. The correlation between the independent variable and dependent variable is zero. B. The independent variables and dependent variable are correlated. C. The independent variable came first and the dependent variable came later. D. There is no other explanation for the relationship.

A. The correlation between the independent variable and dependent variable is zero. Because: Causal Claims — In the case that the correlation is zero, a causal claim cannot be made.

Conceptual Variables

Abstract concepts such as shyness or intelligence. Also known as a construct.

Statistical Validity

Also called statistical conclusion validity, is the extent to which a study's statistical conclusions are accurate and reasonable.

Operational Variables

Also known as operational definitions, or to operationalize. Means to turn a concept of interest into measured or manipulated variable.

Association Claim

Argues that one level of a variable is likely to be associated with a particular level of another variable.

Casual Claim

Argues that one of the variables is responsible for changing the other.

Heather reads an article entitled, "Waist Circumference Associated with Life Expectancy." She wants to use the correlation reported in the article to predict her own life expectancy based on her waist circumference. What kind of correlation would be best for her to make this prediction? A. a zero correlation B. a strong positive correlation C. a weak positive correlation D. a weak negative correlation

B. A strong positive correlation Because: Making Predictions Based on Associations — The stronger a correlation is the better it can be used to make predictions.

What kind of a claim is the following headline making? "Former NFLers at Higher Risk for Brain, Mood Problems." A. frequency claim B. association claim C. causal claim D. anecdotal claim

B. Association Claim Because: Causal Claims — "At higher risk for" is an association claim verb.

It has been reported that half of Americans show road rage. For this claim to have strong external validity, which of the following would have been the best sample for the researcher to have used? A. students from Intro to Psych courses who are earning extra credit B. a cross-section of American drivers representing men and women; people from the city, suburbs, and farms; of all ages C. young men from ages 20 to 30; since they are the group most frequently charged with road rage, they should be the focus D. a random sample of people from a Los Angeles telephone book

B. a cross-section of American drivers representing men and women; people from the city, suburbs, and farms; of all ages Because: Interrogating Frequency Claims — The other choices represent only specific subsets of Americans.

Reading the news on the Internet, Johan comes across the headline, "When Stress is Increased, Men Rush Ahead, Women More Cautious." (This headline is based on a study conducted by Lighthall et al., 2011.) In this study, men and women were asked to perform a decision task as many times as possible in a set period, in either a stressed or unstressed condition. In the unstressed condition, men and women performed similarly. However, in the stressed condition, the number of decision tasks performed by men increased while the number performed by women decreased. In this study, the number of decision tasks performed is best described as which of the following? A. a constant B. a level of a variable C. a manipulated variable D. a measured variable

C. A manipulated Variable Because: The number of decision tasks performed is measured.

For an association claim, you should interrogate all of the following validities EXCEPT __________. A. statistical B. external C. internal D. construct

C. Internal Because: Interrogating Association Claims — Association claims are not asserting causality so internal validity is not relevant to interrogate. Internal validity is relevant when you assert that one variable causes another to change.

Professor Nakum designs a memory experiment to test the effect of word familiarity on memory. Three lists of words are created: common words, uncommon words, and made-up words. Participants are randomly assigned to study one of the lists of 30 words for 5 minutes, do math problems for 5 minutes, then write all the words they recall from the list. Their score is the number of words correctly recalled. The use of random assignment of participants increases which of the following? A. the temporal precedence of the study B. the strength of association of the study C. internal validity of the study D. validity of the study

C. Internal validity of the study Because: Random assignment controlled for possible alternative explanations.

Which of the following claims is an association claim? A. Teenage pot smoking affects intelligence. B. Depression in the elderly may predict dementia. C. Tanning changes the brain. D. A thoughtful gift makes the giver feel closer to the recipient.

C. Tanning changes the brain Because: Causal Claims — "Affects", "changes," and "makes" are causal claim verbs.

Reading the news on the Internet, Johan comes across the headline, "When Stress is Increased, Men Rush Ahead, Women More Cautious." (This headline is based on a study conducted by Lighthall et al., 2011.) In this study, men and women were asked to perform a decision task as many times as possible in a set period, in either a stressed or unstressed condition. In the unstressed condition, men and women performed similarly. However, in the stressed condition, the number of decision tasks performed by men increased while the number performed by women decreased. Which of the following is a variable in this study? A. the decision task type B. the length of the set period C. the amount of stress D. the cause of the stress

C. The amount of stress Because: Variables — The amount of stress is varied between stressed and unstressed.

Professor Nakum designs a memory experiment to test the effect of word familiarity on memory. Three lists of words are created: common words, uncommon words, and made-up words. Participants study one of the lists of 30 words for 5 minutes, do math problems for 5 minutes, then write all the words they recall from the list. Their score is the number of words correctly recalled. How were the words for each list selected? A. to operationalize different levels of the independent variable "difficulty" B. to operationalize different levels of the dependent variable "memory" C. to operationalize different levels of the independent variable "familiarity" D. to confuse participants

C. to operationalize different levels of the independent variable "familiarity" Because: Other Validities to Interrogate in Causal Claim — The lists vary in terms of their familiarity.

Jenny reads the headline, "Tea Party Supporters Have Slipped To 20 Percent." She asks, "What is the margin of error of the estimate?" What validity is she interrogating? A. construct validity B. internal validity C. external validity D. statistical validity

D. Statistical validity Because: Statistical Validity of Frequency Claims — The margin of error of the estimate is a statistical figure that indicates where the true value in the population probably lies.

What is the name for the measured variable in an experiment? A. the constant B. the testing variable C. the independent variable D. the dependent variable

D. The dependent variable Because: In an experiment, the experimenter manipulates one variable, the independent variable, and measures the other, the dependent variable.

There is a negative association between exercise and obesity. Which of the following would a researcher need to demonstrate in order to make the claim that a lack of exercise causes obesity? A. There is a positive relationship between exercise and being thin. B. There are no obese people who exercise. C. The association between exercise and obesity generalizes to the whole population. D. The lack of exercise came before the obesity.

D. The lack of exercise came before the obesity Because: Three Rules for Causation — This is the temporal precedence rule for causation. It is possible that because of the difficulty in exercising, obese people stop exercising after becoming obese.

Professor Nakum designs a memory experiment to test the effect of word familiarity on memory. Three lists of words are created: common words, uncommon words, and made-up words. Participants study one of the lists of 30 words for 5 minutes, do math problems for 5 minutes, then write all the words they recall from the list. Their score is the number of words correctly recalled. Which of the following is the dependent variable in this study? A. the type of word list B. the time spent studying the list C. the length of the list studied D. the number of words correctly recalled

D. The number of words correctly recalled Because: Experiments Can Test Causal Claims — The number of words recalled is what is being measured.

Frequency Claim

Describe a particular rate or degree of a single variable. (Ex: 1 in 25 or 45%)

External Validity

How well the results of a study generalize to, or represent, people or contexts besides those in the study itself.

Covariance

One of three criteria for establishing a casual claim, which states that one variable usually cannot be said to cause another variable unless the two are related.

Measured Variable

One who's levels are simply observed and recorded. (IQ, BP, or even hair color or gender)

Construct Validity

Refers to how well a conceptual variable operationalized.

Validity

Refers to the appropriateness of a conclusion or decision, and in general, a valid claim is reasonable, accurate, and justifiable.

Constant

Something that could potentially vary but has only one level in the study in question.

Variables

Something that varies, must have at least two values.

Claim

The argument someone is trying to make.

Temporal Precedence

The second of three criteria for establishing a casual claim, means that one variable comes first in time, before the other variable. (Ex: to say music lessons improve IQ, music lessons must start before the improvement of IQ).

Internal Validity

The third criteria for establishing a casual claim. Also known as the third variable criteria. Means that a study should be able to eliminate alternative explanations for the association.