Psychological Statistics

Psychological Statistics

 

Question 1. 1.

Identify each of the following as examples of nominal, ordinal, interval, or ratio scales of measurement. (4 points each)

1.A poll of registered voters in Florida asking which candidate they support

2.The length of time required for a wound to heal when using a new medicine

3.The number of telephone calls arriving at a switchboard per five-minute period

4.The distance first-year college football players can kick a ball

5.Mental health diagnoses present in an elderly population

6.The rankings of employees on their job performance

(Points : 24)

1.Nominal

2. Interval

3.Ratio

4.Interval

5.Nominal

6. Ordinal

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?

(Points : 4)

10/200

0.05

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)

45-38=7

7/3=2.33

A z-score of 2.33 is a point that 97.75% of people will take less time that she did.

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)

In chemistry, the z-score is (81-70)/20=11/20=0.55. In history, it is (75-65)/8=10/8=1.25. Both were above the class average, but history he did better.

Question 6. 6. Suppose you want to figure out what to do with your degree in psychology. You ask some fellow students from your psychology program who recently graduated to find out what they are doing with their degree and how much it pays. What type of sampling is this? What are the limitations of this sampling approach? (Points : 8)

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 Âą1 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

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