Stats in Psych and Allied Fields
PSY 205
Stats Homework

Chapter 8: Testing Means Questions

1.
What is the main limitation of
the ztest? Name the alternative to
the ztest that does not have this
limitation.

3.
How does the shape of a tdistribution change as the sample size
increases? Explain

5.
Name the ttest used in hypothesis testing to evaluate the mean observed in
one sample.

11. In the following studies, state whether the one sample ttest is an appropriate test statistic
to analyze data. If not, then explain why it is not appropriate.
a)
A study measuring differences
in attitudes about mortality about Democrats and Republicans.
b)
A study testing night-shift
workers sleep the recommended 8 hours per day.
c)
A study evaluating the body
mass index (BMI) score of athletes compares to the general population.

1.
Will each of the following
increase, decrease, or have no effect on the value of the test statistic in a
one-sample ttest?
a)
The sample size is increased
b)
The level of significance is
reduced from .05 to .01
c)
The sample variance is doubled
d)
The difference between the
sample and population mean is increased

Chapter 9: Testing Means Questions

1.
What is the between-subjects
design?

3 Of the two ways to select two samples
described in this chapter, which type of sampling is commonly used in
experiments?

7.
Name two measures used of
proportions of variance. Which measure is the least conservative?

11. In the
following studies, state whether you would use a one-samplettest or a two- independent-sample ttest.
a)
A study measuring differences
in attitudes about morality among men and women
b)
A study testing whether
night-shift workers sleep the recommended 8 =hours per day
c)
An experiment measuring
differences in the brain activity among rats placed on either a continuous or an
intermittent reward schedule.

13. State the total degrees of freedom for the following t tests:
a)
N = 12 for a one- sample ttest
b)
Df1 =12, n2 = 19 for a two independent- sample t test
c)
Critical value = 1.645 for a
one-tailed test, a = o.5
d)
Critical value = 63.657 for a
two-tailed test, a =.01

15. State the critical values for a two-independent- sample t test given the following conditions:
a)
Two- tailed test, a=
.05, n = 12 in each group
b)
One-tailed test, lower-tail
critical, a = .01
c)
Two-tailed test, a = .01, total df = 26
d)
One- tailed test, upper-tail
crticial, a = .05, nfor both group combined is 30
Chapter 11: One- Way Analysis of Variance

1.
Explain the meaning of the
following terms for ANOVA:
a)
One- way,
b)
Between-subjects,
c)
Within subjects

3
A researcher conducts a one-way
ANOVA in which one independent variable has four levels. How many different
groups are in this study?

7.
Define the following terms:
a)
Sum of squares between groups
b)
Sum of squares error
c)
Mean square between groups
d)
Mean square error

1.
State the degrees of freedom
error in each of the following between-subjects tests.
a)
A researcher tests how nervous
public speakers get in front of a small medium, or large audience. Ten
participants are randomly assigned to each group.
b)
A consultant measures job
satisfaction in a sample of 15 supervisors, 15 managers, or 15 execitives at a
local firm.
c)
A high school counselor has 12
students in each of four classes rate how much they like their teacher.
15
What is the decision at a .05
level of significance for each of the following tests? Hint:find the critical value for each test; then make a decision.
a)
F (3, 26) = 3.00
b)
F (5, 20) = 2.54
c)
F (2, 12) = 3.81
d)
F (4, 30) = 2.72

Chapter 12: Two- Way Analysis of Variance
1.
What is the difference between
a one-way ANOVA and a two-way Anova?

3 Define the following key terms:
a)
Cell,
b)
Main effect,
c)
Interaction,
5.. When looking at a graph of
an A X B interation, describe the pattern that indicats the interaction is
possibly significant.

7.
State fours assumptions between
a one-way ANOVA and a two-way Anova.

1.
State the total number of
groups for each of the following examples of a two- way between- subject ANOVA
test.
a)
A psychologist administers a
small, medium, or large does of drugs to a sample of mice ( facter a: drug
choice) and measures reward – seeking behavior in three- experimental trials (
facter b: trials).
b)
An industrial organizational
psychologist measures the GPA among men and women graduate students ( facter a:
sex) with low, medium, or high leadership potential ( facter b: leader potential).

15
A psychotherapist asks a sample
of violent and nonviolent criminals from impoverished, middle class, and upper-
class backgrounds to indicates how accountable they feel they are for their
crimes. Identify each factor and the levels of each factor in this example.

21. For each of
the following, state whether F = 0 for a main effect, the AX B Interaction, or
both:
a)
Cell means are equal
b)
Row totals are equal
c)
Coloum totals are equal

Chapter 13: (Correlation and Linear Regression)

1.
What is correlation?

3
What information does the
strength of a correlation coefficient convey?

5.
What is coefficient of
determination?

1.
State which correlation
coefficient ( Pearson, Spearman, point- biserial, or phi) should be used given
the following information.
a)
Both factors are interval or
ratio scale
b)
Both factors are ranked
c)
One factor is dichotomous, and
the other factor is continuous

13
State whether each of the
following is either an exampleof a positive correlation or a negative correlation.
a)
Higher education level is
higher associated with a larger annual income
b)
The smaller the class size, the
more students believe they are receiving a quality education

17. A medical student found a negative relationship between exercise (
in minutes per week) and stress related health problems ( r= .26). which of the
following conclusions is appropriate? Explain by the other option is not.
a)
6.76% of the variance in
stress-related health problems can be explained by the amount of weekly
exercise.
b)
Increasing the amount of
exercise per week will cause stress related health problems to decrease.