## PSYC 354 Homework 4

Questions 1-10
Fill in the highlighted blanks to answer/complete the statements.
1)
When a sample has similar characteristics to the population from which it was drawn, the sample is said to be ________.
2)
If a finding based on a sample also applies beyond that sample to the entire population, that finding is said to have high external _______.

3)
The duplication of the results of a research study in a different context or with a different sample is called ________.
4)
Your own estimate of the likelihood that you will win a contest is known as a(n) ________.

5)
Expected relative-frequency probability is computed as the number of ________ divided by the number of ________.

6)
The ________ group is the group receiving the intervention or treatment of interest.

7)
A statement that 2 populations are different from one another is a(n) ________ hypothesis.

8)
If you find that the groups you studied differed from each other more than would be expected by chance alone, you ________ the null hypothesis.

9)
When you fail to reject the null hypothesis but the null hypothesis is in fact false, you have made a(n) ________ error.

10)
When you reject the null hypothesis but the null hypothesis is in fact true, you have made a(n) ________ error.

Question 11a-11b
A school psychologist is interested in whether longer recess breaks affect time on task in the classroom. She divides students into two groups: one with a standard recess length of 10 minutes, and one with a longer recess length of 18 minutes, and assesses their time on task in the classroom over a period of 4 weeks.
11-a) What is the likely null hypothesis for this experiment?
11-b) What is the likely research hypothesis for this experiment?

Question 12-15
Complete the following exercises:
12) What is the probability of hitting a target if, in the long run, 15 out of every 125 attempts actually hit the target?
13) On a TV game show, 6 people have won the grand prize and a total of 159 people have competed. Estimate the probability of winning the grand prize.
14) Convert the following proportions to percentages:
a) 0.356
b) .9
c) .1742
a)
b)
c)

15) Convert the following percentages to proportions:
a) 57.8%
b) .5%
c) 3.3%
a)
b)
c)

Part II & Part III
There is no new SPSS material this module/week. No questions for Part II or III
.

Part IV: Cumulative
Data provided below for Questions 1 and 2.

99.00
96.00
92.00
89.00
85.00
80.00
78.00
76.00
75.00
74.00
72.00
70.00
70.00
67.00
63.00
59.00
53.00

Part IV:
Questions 1a-1b

The final grades for students in a freshman seminar are shown in the left-hand column. Enter the data into a new SPSS data file.

• Create the appropriate SPSS graph to show the distribution of students’ grades.

• Compute descriptive statistics for this data.

• Which measure of central tendency would you use to describe this data?

• Why?

1-a)
Create the appropriate SPSS graph to show the distribution of students’ grades.

1-b)
Compute descriptive statistics for this data.
Which measure of central tendency would you use to describe this data?
Why?
Answer: Appropriate Descriptive Statistics Table

Answer: Measure Of Central Tendency

Explanation/Justification:

City

Livability Rating

Boston
Austin
Chicago
Pittsburgh
San Diego
Jacksonville, FL
Detroit
Miami
New York
Portland
Atlanta
Charlotte

73
83
73
75
80
72
67
71
73
80
78
77

Part IV:
Questions 2a & 2b

• The overall livability ratings of 12 US cities appear in the columns to the left.

• The data are based on data taken from this livability calculator (http://www.areavibes.com/).

• Enter the data in a new SPSS file. When creating the City variable, be sure that the type is set to “string” or “text” in the Variable View window so that the names will show up on the graph.

2-a)
Create the correct type of graph to display this data, and justify your choice of graph.
Answer: paste SPSS graph here

Explanation/Justification:
2-b)
What level of measurement (nom., ord., scale) is the variable “City”?
What level of measurement is the variable “Livability Rating”?