Expert Answers

Part I: Computation and Short Answer (80 points)
Question 1.1.
Identify each of the following as examples of nominal, ordinal, interval, or ratio scales of measurement. (4 points each)
A poll of registered voters in Florida asking which candidate they support
The length of time required for a wound to heal when using a new medicine
The number of telephone calls arriving at a switchboard per five-minute period
The distance first-year college football players can kick a ball
Mental health diagnoses present in an elderly population
The rankings of employees on their job performance
Question 2.2.
Two hundred raffle tickets are sold. Your friend has five people in her family who each bought two raffle tickets. What is the probability that someone from her family will win the raffle?
Question 3.3. Jolie has 45 minutes to do her statistics homework. If the mean is 38 minutes and the standard deviation is 3, calculate Jolie’s z score. Once calculated, interpret your findings in terms of Jolie’s performance.
(HINT: use the normal distribution and the probability that other students performed better or worse.) (Points : 8)
Question 4.4. A psychologist measures units of change for a memory test after students are given an opportunity to sleep only four hours. The following change units were obtained: 7, -12, 4, -7, 3, -10. Find the a) mean, b) median, c) mode, d) standard deviation, e) range, and f) variance. (Points : 24)
Question 5.5. A student scored 81 on a chemistry test and 75 on a history test. For the chemistry test, the mean was 70 and the standard deviation was 20. For the history test, the mean was 65 and the standard deviation was 8. Did the student do better on the chemistry test or the history test? Explain your answer. (Points : 12)
Question 7.7. Variables in which the values are categories are known as (Points : 4)
Interval variables
Nominal variables
Ordinal variables
Ratio variables
Question 8.8. Before the researcher can conduct a statistical test, the research question must be translated into (Points : 4)
A testable hypothesis
Additional observations
Mathematical symbols
Numbers
Question 9.9. The hypothesis stating that there are no differences, effects, or relationships is (Points : 4)
The alternative hypothesis
The baseline hypothesis
The null hypothesis
The reasonable hypothesis
Question 10.10. A group of students made the following scores on a 10-item quiz in psychological statistics: {5, 6, 7, 7, 7, 8, 8, 9, 9, 10, 10} What is the mean score? (Points : 4)
6.6
7.2
7.8
8.7
Question 11.11. A group of students made the following scores on a 10-item quiz in psychological statistics: {5, 6, 7, 7, 7, 8, 8, 9, 9, 10, 10} What is the median score? (Points : 4)
6
7
8
9
Question 12.12. A group of students made the following scores on a 10-item quiz in psychological statistics: {5, 6, 7, 7, 7, 8, 8, 9, 9, 10, 10} What is the mode? (Points : 4)
5
7
8
9
Question 13.13. A group of students made the following scores on a 10-item quiz in psychological statistics: {5, 6, 7, 7, 7, 8, 8, 9, 9, 10, 10} What is the range of scores? (Points : 4)
5
6
7
11
Question 14.14. A group of students made the following scores on a 10-item quiz in psychological statistics: {5, 6, 7, 7, 7, 8, 8, 9, 9, 10, 10} What is the variance, treating these scores as a sample? (Points : 4)
1.53
1.60
2.33
2.56
Question 15.15. The standard normal distribution has all the following properties EXCEPT: (Points : 4)
The mean, mode, and median are all equal
The total area under the curve equals 1
The curve is specified by two parameters, the mean and the standard deviation
The curve extends to + and – 3 standard deviations from the mean
Question 16.16. According to the Empirical Rule, approximately _______% of the data in a normal distribution will fall within ±1 standard deviation of the mean. (Points : 4)
34
68
95
99.7
Question 17.17. In statistical computations, the number of values that are free to vary is known as (Points : 4)
Degrees of freedom
Freedom factor
Variability index
Variation quotient
Question 18.18. Which of the following reflects a Type I error? (Points : 4)
Rejecting the null hypothesis when in reality the null hypothesis is true
Rejecting the null hypothesis when in reality the null hypothesis is false
Accepting the null hypothesis when in reality the null hypothesis is true
Accepting the null hypothesis when in reality the null hypothesis is false

Question 19.19. Which type of sampling is used when the experimenter asks 5 area doctors to refer pregnant women to his study and accepts all women who offer to be in his study? (Points : 4)
purposive sampling
convenience sampling
cluster sampling
stratified sampling
Question 20.20. In our statistics equations, n refers to: (Points : 4)
mean
standard deviation
normal distribution
number of subjects
Question 21.21. Which of the following is true regarding alpha? (Points : 4)
it is also known as the level of significance
value is set by the researcher
value is equal to the probability of a type I error
all of the above are true
Question 22.22. Macy proposes that boys who play sports are viewed as more attractive than boys who do not play sports. What is her null hypothesis? (Points : 4)
Boys who play sports are not viewed as more attractive than boys who do not play sports
Playing sports will influence how attractively boys are viewed
Boys who play sports are more attractive than girls who play sports
There can be no null hypothesis
Question 23.23. You calculate a t of 2.38 and note that the tabled value for .01 is 3.22 and for .05 is 2.19. You would conclude that the null hypothesis can be: (Points : 4)
Accepted at the .05 level
Rejected at the .01 level
Rejected at the .05 level
None of the above
Question 24.24. A researcher is studying political conservatism among 11 engineering students and 11 humanities students. The number of degrees of freedom for a t test is: (Points : 4)
22
20
11
10
Question 25.25. A t test for dependent groups should be used instead of a t test for independent samples: (Points : 4)
If each participant is measured twice
Whenever there are equal numbers of subjects in each group
Whenever there are only two groups
All of the above
Question 26.26. In a normal distribution, what percent of the population falls within one and two standard deviations of the mean? (Points : 4)
Not sure about this one
34%
68%
95%
cannot tell from the information given
Question 27.27. Which of the following is more affected by extreme scores? (Points : 4)
Mode
Mean
Median
None of the above are affected
Question 28.28. On a histogram, what does the vertical (y) axis refer to? (Points : 4)
Individual scores
Frequencies
Means
Deviation scores
Question 29.29. Which statistic refers to the average amount by which the scores in the sample deviate from the mean? (Points : 4)
Range
Standard deviation
Median
Mode
Question 30.30. Assume a normal distribution for N = 300. How many cases would one expect to find between +1 and -1 standard deviations around the mean? (Points : 4)
102
285
150
204
Question 31.31. A z score of zero tells us that the score is at the________of the distribution. (Points : 4)
Mean
Very top
Very bottom
None of the above since z cannot be zero
Question 32.32. In a unit normal curve, what goes on the x axis? (Points : 4)
Frequencies
Observed scores
z scores
Area
Question 33.33. Which of the following is a measure of variability? (Points : 4)
Mean
Range
Interval
All of the above
Question 34.34. The only measure of central tendency that can be found for nominal data is the (Points : 4)
Mean
Median
Mode
Midrange
Question 35.35. If the probability of event A is 0.45 and the probability of event B is 0.35 and the probability of A and B occurring together is 0.25, then the probability of A OR B is: (Points : 4)
0.8
1.8
0.1575
0.55
Question 36.36. A researcher knows that the average distance commuting students live from campus was previously 8.2 miles. Because of the rising prices of gasoline, the research wants to test the claim that commuting students now live closer to campus. What is the correct alternative hypothesis? (Points : 4)
The new mean distance is 8.2 miles.
The new mean distance is less than or equal to 8.2 miles.
The new mean distance is less than 8.2 miles.
The new mean distance is greater than or equal to 8.2 miles.