Question 1

Fiona,a quantitative psychologist,is interested in using inferential statistics because they provide ____.

Accepted Answer

Inferential statistics provide a measure of how likely it is that a result came about by chance, which is important in determining the significance of findings and making generalizations about a population based on a sample.

Question 2

In a normal distribution of scores,which of the following is true?

Accepted Answer

In a normal distribution, about 5 percent of the scores are located more than two standard deviations from the mean. The mean is not always 0, and most scores are not located in the tails at either end of the distribution. The standard deviation indicates the average amount of variability in the scores, not the arithmetic average score.

Question 3

Francesca is at a casino watching a game involving dice.She determines that one of the dice is loaded,causing it to turn up "3" more often than would be expected by chance.To know for certain if this was true,Francesca would have to conduct a study to determine if her findings have statistical ____.

Accepted Answer

Statistical significance is the level of probability one is willing to accept to reject the null hypothesis. It determines whether an observed effect is real or just a chance occurrence. In this scenario, Francesca needs to conduct a study to determine if her findings have statistical significance, i.e., if the loaded dice's outcome is not due to random chance alone. Therefore, option A is the correct answer. Options B, C, and D, i.e., power, validity, and generalizability, do not fit the given scenario.

Question 4

In Diti's study,employees who listened to rap music produced an average of 5.71 units and employees who listened to polka music produced an average of 2.71 units.To see if the difference between these means is statistically significant,Diti should ____.

Accepted Answer

To determine if the difference between means is statistically significant, a t test should be conducted. The other options (calculating a correlation coefficient, examining medians, and calculating percentiles) are not appropriate for testing the difference between means.

Question 5

Joe has collected data on the number of hours ten-year-olds spend watching television each week.He tells you that the distribution of scores followed a truly normal curve.Which of the following is suggested by Joe's statement?

Accepted Answer

In a truly normal distribution, the mean, median, and mode are all the same value, which divides the distribution into two equal halves. Therefore, fifty percent of the scores fall below the mean.

Question 6

In a memory experiment,Dr.Nall finds that the difference in the mean number of nonsense syllables remembered by Group A vs.Group B is statistically significant at the p < .05 level.This means that ____.

Accepted Answer

A p-value less than .05 means that there is less than a 5% chance that the observed difference in mean scores between Group A and Group B is due to chance. This is the standard level of statistical significance used in psychology research. Therefore, choice A is the correct answer. The other choices are not relevant to the given information.

Question 7

Jebreel is a graduating senior who must decide among four job offers in four different cities.He wants to move to a city where he can wear the same clothes all year.The standard deviations of temperature in these cities are given below.Which city should Jebreel choose?

Accepted Answer

Jebreel should choose the city with the lowest standard deviation of temperature as this indicates that the temperature in that city does not change much throughout the year, allowing him to wear the same clothes year-round. Out of the given options, city A has the lowest standard deviation of temperature at 8.19, making it the best choice for Jebreel.

Question 8

Crystal received her SAT score from her counselor.She scored two standard deviations above the mean.What does this indicate about <st2:givenname w:st="on">Crystal's score?

Accepted Answer

Two standard deviations above the mean corresponds to the 97.5th percentile, meaning Crystal's score was higher than 97.5 percent of the other scores.

Question 9

What does it mean if the standard deviation of a distribution of quiz grades is 0?

Accepted Answer

A standard deviation of 0 indicates that there is no variation in the data, meaning that every student received the same grade.

Question 10

Which of the following is a characteristic of a normal distribution?

Accepted Answer

The mean, median, and mode are equal in a normal distribution, which is one of its defining characteristics. This property indicates that the distribution is symmetric around its central value.

Question 11

In Dr.Dalbey's study,women missed an average of three work days a year because of colds,and men missed an average of five work days because of colds.To see if the difference between these means is statistically significant,Dr.Dalbey should ____.

Accepted Answer

To determine if the difference between two means is statistically significant, a t-test is appropriate. Therefore, Dr. Dalbey should conduct a t-test to analyze the difference between the mean number of work days missed by women and men due to colds.

Question 12

Dr.Yodela wants to find out whether there is a significant difference in the mean scores of two groups on his new intelligence test.Which statistic should Dr.Yodela use?

Accepted Answer

A t test is used to compare the means of two groups and determine if there is a significant difference between them. It takes into account the sample size and variability of the scores in each group. This would be the best choice for Dr. Yodela to use in order to test his hypothesis.

Question 13

As a researcher,you are interested in how the scores in your data set are dispersed.Specifically,you want to know the average difference between each score and the mean.You would find out this information by looking at the ____.

Accepted Answer

The average difference between each score and the mean is the definition of standard deviation. Range only tells you the difference between the highest and lowest score, while variance measures how spread out the scores are relative to the mean, but not the actual average difference between each score and the mean. Correlation coefficient measures the strength and direction of the relationship between two variables, and is not relevant to this question.

Question 14

Edhilvia is studying the relationship between smoking and number of visits to the doctor.After giving a survey to 1,000 people,she finds that the more people smoked,the more times they visited the doctor every year.From these results,Edhilvia can logically conclude that ____.

Accepted Answer

Edhilvia found that as the number of cigarettes smoked increased, the number of visits to the doctor also increased. This indicates a positive correlation between smoking and visiting the doctor. Option A is incorrect as it suggests a negative correlation. Option C is also incorrect as correlation does not necessarily imply causation. Option D is irrelevant as the question does not concern random assignment of participants to groups.

Question 15

Hui-Hui has just received her scores on the Scholastic Achievement Test (SAT)and learns that her score was at the 84th percentile.Hui-Hui's score represents a standard score of ____.

Accepted Answer

A score at the 84th percentile indicates that Hui-Hui scored higher than 84% of test-takers. To calculate the standard score, we use the formula:

Standard score = (percentile rank - 50) / 10

Plugging in Hui-Hui's percentile rank: 
Standard score = (84 - 50) / 10 
Standard score = 3.4/1 
Standard score = +3.4

Since this is a high positive score, the closest option is A (+1).

Question 16

You are conducting a survey of international students studying at your university.Several of the questions on the survey try to determine how much exposure to American culture the student had before coming to the United States.You suspect that the more exposure the student had before arriving here,the fewer problems of adjustment he or she will report.You are looking for a(n)____.

Accepted Answer

A negative correlation is expected because as the exposure to American culture increases (before coming to the U.S.), the problems of adjustment reported by the student are expected to decrease.

Question 17

If an IQ test is constructed to have a mean of 100 and a standard deviation of 16,approximately what percentage of scores falls between 84 and 116?

Accepted Answer

Because the IQ test has a mean of 100 and a standard deviation of 16, we know that 68% of the scores fall within one standard deviation of the mean. Therefore, approximately 34% of scores are between the mean (100) and one standard deviation below the mean (100-16=84), and approximately 34% of scores are between the mean and one standard deviation above the mean (100+16=116). Adding these two percentages together gives us approximately 68%. Therefore, the correct answer is C) 68 percent.

Question 18

Richard Simmons wants to know whether his original weight-loss system (Simmons I)is as effective as his new weight-loss system (Simmons II).His results indicate that people on Simmons I lose an average of 28.5 pounds in six months and people on Simmons II lose an average of 30.1 pounds in six months.What type of statistics should Richard use to see if the Simmons II system is really better than the Simmons I system?

Accepted Answer

Richard should use inferential statistics to determine whether there is a significant difference between the two weight-loss systems. Inferential statistics involve making inferences about a larger population based on a sample of data, which would allow Richard to determine whether the difference in weight loss between the two systems is likely due to chance or to a real difference in effectiveness. Descriptive statistics (B) would not be sufficient to make this determination, as they only summarize and describe the data without making any inferences. The mean (C) is a measure of central tendency that could be used to compare the average weight loss between the two systems, but it alone would not provide enough information to determine whether the difference was statistically significant. The mode (D), which is the most common value in a set of data, would not be useful in this case as the weight loss values are continuous and not likely to have a clear mode.

Question 19

<st2:personname w:st="on">Professor Goranson studies the relation between adolescents' self-esteem and the number of close friends they report having.After completing her statistical analyses,Professor Goranson finds that as the number of close friendships increased,adolescents' self-esteem rose moderately.Which correlation coefficient did she likely obtain?

Accepted Answer

A positive correlation coefficient indicates that as one variable increases, the other variable also increases. In this case, as the number of close friendships increased, self-esteem also increased moderately. A correlation coefficient of +0.46 suggests a moderate positive correlation between the two variables. The other answer choices suggest negative correlations, which do not accurately reflect the relationship between the variables in this scenario.

Question 20

Clint has learned his standard score on a standardized achievement test is -1 (minus one).What percentage of test takers performed better than Clint?

Accepted Answer

A standard score of -1 corresponds to the 16th percentile, meaning 84 percent of test takers scored higher than Clint.

Quiz 20: Appendix B: Behavioral Genetics.