Q: Which of the following formulas correctly represents the calculation of the mean for a set of scores $$x_1$$, $$x_2$$, ..., x_n$$?

$$ \text{Mean} = \frac{x_1 + x_2 + ... + x_n}{n} $$

Question 1

A researcher wants to study whether drinking green tea improves memory. She randomly assigns participants to two groups: one drinks green tea daily, the other drinks water. After a month, she tests their memory. Which of the following best identifies the independent and dependent variables in this experiment?

Accepted Answer

Independent variable: type of beverage; Dependent variable: memory test scores

Question 2

Which of the following best describes a confound in an experimental design?

Accepted Answer

A variable other than the independent variable that differs between groups and could account for changes in the dependent variable

Question 3

A psychologist observes children playing in a park without interacting with them and records the frequency of aggressive behaviors. Which research method is being used?

Accepted Answer

Naturalistic observation

Question 4

If a correlation coefficient between hours of sleep and test performance is $$r = -0.75$$, what does this indicate?

Accepted Answer

There is a strong negative relationship: as hours of sleep increase, test performance decreases

Question 5

Which of the following is an example of an operational definition for 'stress' in a research study?

Accepted Answer

'Stress' is defined as the score obtained on the Perceived Stress Scale questionnaire

Question 6

A researcher wants to generalize her findings to all college students in the country. Which sampling method should she use to maximize representativeness?

Accepted Answer

Random sampling from the entire population of college students

Question 7

Which of the following best describes the placebo effect?

Accepted Answer

Improvement reported because of expectation for improvement, despite the absence of the independent variable

Question 8

A researcher finds that the mean score on a test is 70, the median is 65, and the mode is 60. What does this suggest about the distribution of scores?

Accepted Answer

The distribution is positively skewed (tail to the right)

Question 9

Which of the following formulas correctly represents the calculation of the mean for a set of scores $$x_1$$, $$x_2$$, ..., x_n$$?

Accepted Answer

$$ 	ext{Mean} = \frac{x_1 + x_2 + ... + x_n}{n} $$

Question 10

In a study, the standard deviation of test scores is low. What does this indicate about the scores?

Accepted Answer

Most scores are close to the mean

Question 11

A researcher conducts an experiment and finds $$p \u003c 0.05$$ when comparing two groups. What does this mean in terms of statistical significance?

Accepted Answer

There is less than a 5% probability that the results are due to chance, so the null hypothesis is rejected

Question 12

Which of the following best illustrates the difference between descriptive and inferential statistics?

Accepted Answer

Descriptive statistics summarize data; inferential statistics test hypotheses and draw conclusions about populations

Question 13

A researcher wants to know if a new teaching method causes better exam performance. She randomly assigns students to two groups, gives one group the new method and the other the traditional method, and compares their scores. Which research method is this?

Accepted Answer

Experimental

Question 14

Which of the following is a key advantage of experimental design over correlational design?

Accepted Answer

Ability to determine cause and effect relationships

Question 15

A researcher uses a self-report survey to measure participants' exercise habits. What is a potential limitation of this method?

Accepted Answer

Participants may give socially desirable answers rather than truthful ones

Question 16

Which of the following best describes the null hypothesis ($$H_0) in $$significance testing?

Accepted Answer

$$ H_0: 	ext{There is no significant difference between groups} $$

Question 17

A researcher wants to test whether caffeine affects reaction time. She gives one group caffeinated coffee and another group decaf, without telling either group which they received. She also does not know which group is which during data collection. What is this procedure called?

Accepted Answer

Double-blind

Question 18

Which of the following is the correct formula for the range of a set of scores?

Accepted Answer

$$ 	ext{Range} = 	ext{Highest score} - 	ext{Lowest score} $$

Question 19

A study finds a correlation coefficient of $$r = 0.00$$ between two variables. What does this mean?

Accepted Answer

There is no relationship between the two variables

Question 20

Which of the following scenarios best illustrates the concept of demand characteristics?

Accepted Answer

Participants guess the purpose of the study and change their behavior to fit what they think the researcher wants

The Scientific Method and Research Methods in Psychology

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