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Time to Practice – Week Three
PSYCH/625 Version 1
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Time to Practice – Week Three
Complete both Part A and Part B below.
Part A
1. For the following research questions, create one null hypothesis, one directional research hypothesis,
and one non-directional research hypothesis.
a. What are the effects of attention on out-of-seat classroom behavior?
Null hypothesis- there are no effects of attention on out of seat classroom behavior?
Directional hypothesis-Lack of attention negatively affects out-of –seat classroom behavior
Non- directional hypothesis- Attention effects out of seat class room behaviors
b. What is the relationship between the quality of a marriage and the quality of the spouses’
relationships with their siblings?
Null hypothesis- There is no relationship between quality of marriage and quality of spouses with their
siblings.
Directional hypothesis- there is better marriage where the spouse has good relationship with their siblings
Non- directional – The quality of spouse relationship with siblings affects the quality of marriage.
2. Provide one research hypothesis and an equation for each of the following topics:
a. The amount of money spent on food among undergraduate students and undergraduate studentathletes.
Amount of money spent on food for undergraduate students is more than for undergraduate students’
athletes.
Eqn. H1: XUs ≠ X Usa
b. The effects of Drug A and Drug B on a disease.
Effects of drug A is higher than drug B on a disease
Eqn. H1: XdA ≠XdB
c. The time to complete a task in Method 1 and Method 2.
Method 1 take less time to complete a task than Method 2
Eqn. H1:Xm1 ≠Xm2
3. Why does the null hypothesis presume no relationship between variables?
asserts that the samples being compared or contrasted are drawn from the same population
with regard
to the outcome variable
4. Create a research hypothesis tested using a one-tailed test and a research hypothesis tested using a
two-tailed test.
The population mean score of students taking an exam between 2013and 2015 was 558 ±139 (µ ± s).
Suppose a sample of 100 participants (n =100) is selected. If the sample mean is 585
(µ =585). Compute the one–tailed and two-tailed sample z-test whether or not to retain the null hypothesis
(µ =558) at a 5% level of significance.
5. What does the critical value represent?
Is the value that defines the boundaries in which the null hypothesis is assumed to be true
6. Given the following information, would your decision be to reject or fail to reject the null hypothesis?
Setting the level of significance at .05 for decision making, provide an explanation for your conclusion.
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Time to Practice – Week Three
PSYCH/625 Version 1
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a. The null hypothesis that there is no relationship between the type of music a person listens to and
his crime rate (p < .05). Reject the null hypothesis, because the crime is not related to type
music.
b. The null hypothesis that there is no relationship between the amount of coffee consumption and
GPA (p = .62). Accept the null hypothesis, because the there is a relationship between the
amount of coffee consumed and GPA.
c. The null hypothesis that there is no relationship between the number of hours worked and level of
job satisfaction (p = .51). Accept the null hypothesis because there is the relationship between
the numbers of hours worked and level of job satisfaction.
7. Why is it harder to find a significant outcome (all other things being equal) when the research
hypothesis is being tested at the .01 rather than the .05 level of significance?
At 0.01 level of significance is too small and the likelihood of the outcome being equal narrow to almost
none.
8. Why should we think in terms of “failing to reject” the null rather than just accepting it?
Acceptance imply the null hypothesis is true while failure to reject is where it is inferred that, the data are
not sufficiently persuasive for us to prefer the alternative hypothesis over the null hypothesis
9. When is it appropriate to use the one-sample z test?
when we know the standard deviation of the population
Part B
Complete the following questions. Be specific and provide examples when relevant.
Cite any sources consistent with APA guidelines.
Question
Answer
The average raw math achievement score for
third graders at a Smith elementary school is
137; There are 100 third graders at Smith
Elementary school. Third graders statewide
score an average of 124 with a standard
deviation applying the eight steps of the
hypothesis testing process as demonstrated on
pp. 185–187 of Statistics for People Who (Think
they) Hate Statistics of 7. Are the Smith third
graders better at math than third graders
throughout the state? Perform the correct
statistical test,
Null hypothesis(H0:)- there is no difference in Smith’s third grader and
statewide third grade
Alternative hypothesis (H1 :) - there is a difference in Smith’s third grade and
statewide third grade.
Under null M=0;
given M= 124, sigma=7 and x=137, sample size =100 and assuming
standard deviation =7
then:
What is a research question that you would like
to answer? Write the null and research
hypotheses. Would you use a one- or two-tailed
test? Why?
Research question-Is the exercise lead to weight loss?
Null hypotheses- Exercise does not lead to weight loss
Research hypothesis- Exercise lead to weight loss
I would use two-tailed test. Because you can use both halves of alpha testing
the significance test in both directions
What do we mean when we say that a
statistical result is significant? What is the
difference between a statistically significant and
Statistic significant result is when you are very sure that the statistic is
reliable. The difference is being significant has a level of uncertainty though
reliable while a meaningful result can be used in decision making.
N Mean SE Mean
95% CI
Z P
100 124.000 0.700 (122.628, 125.372) 177.14 0.000
Solution. Reject the Null Hypothesis.
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Time to Practice – Week Three
PSYCH/625 Version 1
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a meaningful result? Why is statistical
significance important?
Significance is importance because it tells how sure you are that a difference
or relationship exists.
Describe a Type I error for the previous study
that compares third graders’ math achievement.
Describe a Type II error for that study.
Type I error is the probability of rejecting a null hypothesis that is actually
true. There is no difference in Smith’s third grade and statewide third grade.
Type II error is the probability of retaining a null hypothesis that is actually
false. There is a difference in smith third grade and statewide third grade
Reference
Lehmann, E. L., & Romano, J. P. (2007) Testing statistical hypotheses (3rd ed.). New York, NY:
Springer-Verlag New York.
Shi, N.-Z., & Tao, J. (2008) Statistical hypothesis testing: theory and methods. Singapore: World
Scientific Publishing Co Pte.
Statistics Education (2011) SpringerReference.http://doi.org/10.1007/springerreference_205175
Trosset, M. W. (2008). An Introduction to Statistical Inference and its Applications with R (1st
ed.). Boca Raton: Chapman & Hall/CRC.
Copyright © 2014 by University of Phoenix. All rights reserved.