# PYCH 625 Week 2 Practice

University of Phoenix Material

Time to
Practice – Week Two

Complete Parts A,
B, and C below.

Part A

1.     Why is a z
score a standard score? Why can standard scores be used to compare scores from
different distributions?

2.     For the following set of scores, fill in the
cells. The mean is 74.13 and the standard deviation is 9.98.

Raw score

Z score

68.0

?

?

–1.6

82.0

?

?

1.8

69.0

?

?

–0.5

85.0

?

?

1.7

72.0

?

3.     Questions 3a through 3d are based on a
distribution of scores with  and the standard deviation =
6.38. Draw a small picture to help you see what is required.

a.     What
is the probability of a score falling between a raw score of 70 and 80?

b.    What
is the probability of a score falling above a raw score of 80?

c.     What
is the probability of a score falling between a raw score of 81 and 83?

d.    What
is the probability of a score falling below a raw score of 63?

4.     Jake
needs to score in the top 10% in order to earn a physical fitness certificate.
The class mean is 78 and the standard deviation is 5.5. What raw score does he
need?

From
Salkind (2011). Copyright © 2012 SAGE. All Rights Reserved. Adapted with
permission.

Part B

The
questions in Part B require that you access data from Using
SPSS for Windows and Macintosh. This data is available on the
student website under the Student Text Resources link.

The
data sets for problems 5 and 6 can be found through the Pearson Materials in
the Student Textbook Resource Access link, listed under Academic Resources. The
data is listed in the data file named Lesson 20 Exercise File 1. Answer Exercises 5
and 6 based on the following research problem:

Ann
wants to describe the demographic characteristics of a sample of 25 individuals
who completed a large-scale survey. She has demographic data on the
participants’ gender (two categories), educational level (four categories),
marital status (three categories), and community population size (eight
categories).

5.     Using
IBM® SPSS® software, conduct a frequency analysis on the
gender and marital status variables. From the output, identify the following:

a.     Percent
of men

b.    Mode
for marital status

c.     Frequency
of divorced people in the sample

6.     Using
IBM® SPSS® software, create a frequency table to
summarize the data on the educational level variable. Copy and paste the output
from IBM® SPSS® into this worksheet.

7.     The
data set for this problem can be found through the Pearson Materials in the
Student Textbook Resource Access link, listed under Academic Resources. The
data is listed in the data file named Lesson 21 Exercise File 1. David collects
anxiety scores from 15 college students who visit the university health center
during finals week. Compute descriptive statistics on the anxiety scores. From
the output, identify the following:

a.     Skewness

b.    Mean

c.     Standard
deviation

d.    Kurtosis

From Green
& Salkind (2011). Copyright © 2012 Pearson Education. All Rights Reserved.
Adapted with permission.

Part C

Complete the questions below. Be specific and provide examples when relevant.

Cite any sources consistent with APA guidelines.

Question

Answer

What is
the relationship between reliability and validity? How can a test be reliable
but not valid? Can a test be valid but not reliable? Why or why not?

How does
understanding probability help you understand statistics?

How could
you use standard scores and the standard distribution to compare the reading
scores of two students receiving special reading resource help and one
student in a standard classroom who does not get special help?

In a standard normal distribution: What does a z score of 1 represent? What percent
of cases fall between the mean and one standard deviation above the mean?
What percent fall between the mean and –1 to +1 standard deviations from the
mean? What percent of scores will fall between –3 and +3 standard deviations
under the normal curve?