# QUIZ PSYCHOLOGICAL STATISTICS

M3A2 LASA 1 QUIZ

PSYCHOLOGICAL STATISTICS

>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 a time of 45 minutes for doing 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.
 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.
 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?
 Question 7.7. Variables in which the values are categories are known as

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

A testable hypothesis
Additional observations
Mathematical symbols
Numbers

 Question 9.9. The hypothesis stating that there are no differences, effects, or relationships is

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?

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?

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?

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?

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.

34

68
95
99.7

 Question 17.17. In statistical computations, the number of values that are free to vary is known as

Degrees of freedom
Freedom factor
Variability index
Variation quotient

 Question 18.18. Which of the following reflects a Type I error?

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? ()

purposive sampling
convenience sampling
cluster sampling
stratified sampling

 Question 20.20. In our statistics equations, n refers to:

mean
standard deviation
normal distribution
number of subjects

 Question 21.21. Which of the following is true regarding alpha?

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?

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:

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: (

22
20
11
10

 Question 25.25. A t test for dependent groups should be used instead of a t test for independent samples: (

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 between -1 and 1 standard deviations of the mean?

34%
68%
95%
cannot tell from the information given

 Question 27.27. Which of the following is more affected by extreme scores?

Mode
Mean
Median
None of the above are affected

 Question 28.28. On a histogram, what does the vertical (y) axis refer to?

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?

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?

102
285
150
204

 Question 31.31. A z score of zero tells us that the score is at the________of the distribution.

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?

Frequencies
Observed scores
z scores
Area

 Question 33.33. Which of the following is a measure of variability?)

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

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:

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?

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.

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