Chapter 1, number 1.8 Indicate whether each of the following studies is an experiment or an observational study. If it is an experiment, identify the independent variable and note any possible confounding variables. a. A psychologist uses chimpanzees to test the notion that more crowded living conditions trigger aggressive behavior. Chimps are placed, according to an impartial assignment rule, in cages with either one, several, or many other chimps. Subsequently, during a standard observation period, each chimp is assigned a score based on its aggressive behavior toward a chimplike stuffed doll. b. An investigator wishes to test whether, when compared with recognized scientists, recognized artists tend to be born under different astrological signs. c. To determine whether there is a relationship between the sexual codes of primitive tribes and their behavior toward neighboring tribes, an anthropologist consults available records, classifying each tribe on the basis of its sexual codes (permissive or repressive) and its behavior toward neighboring tribes (friendly or hostile). d. In a study of group problem solving, an investigator assigns college students to groups of two, three, or four students and measures the amount of time required by each group to solve a complex puzzle. e. A school psychologist wishes to determine whether reading comprehension scores are related to the number of months of formal education, as reported on school transсrіpts, for a group of 12-year-old migrant children. f. To determine whether Graduate Record Exam (GRE) scores can be increased by cramming, an investigator allows college students to choose to participate in either a GRE test-taking workshop or a control (non-test-taking) workshop and then compares the GRE scores earned subsequently by the two groups of students. g. A social scientist wishes to determine whether there is a relationship between the attractiveness scores (on a 100-point scale) assigned to college students by a panel of peers and their scores on a paper-and-pencil test of anxiety. h. A political scientist wishes to determine whether males and females differ with respect to their attitudes toward defense spending by the federal government. She asks each person if he or she thinks that the current level of defense spending should be increased, remain the same, or be decreased. i. Investigators found that four year-old children who delayed eating one marshmallow in order to eat two marshmallows later, scored higher than non-delayers on the Scholastic Aptitude Test (SAT) taken over a decade later. Chapter 2, number 2.14 Construct a frequency distribution for the number of different residences occupied by graduating seniors during their college career, namely 1, 4, 2, 3, 3, 1, 6, 7, 4, 3, 3, 9, 2, 4, 2, 2, 3, 2, 3, 4, 4, 2, 3, 3, 5( What is the shape of this distribution? Chapter 3, number 3.10 During their first swim through a water maze, 15 laboratory rats made the following number of errors (blind alleyway entrances): 2, 17, 5, 3, 28, 7, 5, 8, 5, 6, 2, 12, 10, 4, 3. a. Find the mode, median, and mean for these data. b. Without constructing a frequency distribution or graph, would you characterize the shape of this distribution as balanced, positively skewed, or negatively skewed? Chapter 3, number 3.17 Indicate whether each of the following distributions is positively or negatively skewed. The distribution of a. incomes of taxpayers has a mean of $48,000 and a median of $43,000. b. GPAs for all students at some college has a mean of 3.01 and a median of 3.20. c. number of “romantic affairs” reported anonymously by young adults has a mean of 2.6 affairs and a median of 1.9 affairs. d. daily TV viewing times for preschool children has a mean of 55 minutes and a median of 73 minutes. Chapter 4, number 4.17 Why can′t the value of the standard deviation ever be negative? Chapter 4, number 4.19 Referring to Review Question 2.18 on page 46, would you describe the distribution of majors for all male graduates as having maximum, intermediate, or minimum variability? (Here is Review Question 2.18)-DO NOT HAVE TO COMPLETE Indicate whether each of the following statements about degrees of freedom is true or false. Degrees of freedom refer to the number of values free to vary in the population. One degree of freedom is lost because, when expressed as a deviation from the sample mean, the final deviation in the sample fails to supply information about population variability. Degrees of freedom makes sense only if we wish to estimate some unknown characteristic of a population. Degrees of freedom reflect the poor quality of one or more observations.
