Question

- A researcher wants to determine if frustration increases one’s
level of aggression and randomly selects two groups of subjects
from a class of 80 students. The experimental group (n1 = 40) will
have to solve a frustrating puzzle, while the control group (n2 =
40) will take a 1-hour break. After one hour, the researcher
measures the level of the students’ aggression using a short
survey. The calculated mean of aggression for the experimental
sample is 4.0 (std. deviation = 2.0) and for the control group the
mean of aggression is 3.0 (std. deviation
= 1.5).
*(12 points)*

- Formulate the null and the alternative (research) hypotheses
- Test the null hypothesis [using the appropriate statistic] and reach a statistical conclusion [i.e., do you reject, or do you fail to reject the null hypothesis?]
- Interpret your findings [i.e., if you reject (or not)
H
_{0}, what does this mean?]. Did having to solve the puzzle increase one’s level of aggression

Answer #1

A researcher wants to determine whether or not a given drug has
any effect on the scores of human subjects performing a task of ESP
sensitivity. He randomly assigns his subjects to one of two groups.
Nine hundred subjects in group 1 (the experimental group) receive
an oral administration of the drug prior to testing. In contrast,
1000 subjects in group 2 (control group) receive a placebo (dummy).
The results of the study found the following: For the drug group,...

2) How does the neurotransmitter serotonin influences
aggression? A researcher conducts a study examining how the brain
chemical serotonin is related to aggression. Two samples were
collected; one sample serves as the control group which will not
receive any treatment drug, the second sample receives a drug that
affects serotonin and thus influences aggression. The researcher
finally tests the animals by recording the number of aggressive
responses. The following results were reported:
Treatment group (serotonin
affected):
Control
group:
Rat...

A researcher wants to study the relationship between salary and
gender. She randomly selects 316individuals and determines their
salary and gender. Can the researcher conclude that salary and
gender are dependent?
Income
Male
Female
Total
Below $25,000$
36
68
104
$25,000-$50,000
54
43
97
$50,000-$75,000
42
31
73
Above $75,000
23
19
42
Total
155
161
316
-Find the critical value of the test at the 0.01 level of
significance. Round your answer to three decimal places.
-Make the decision...

A researcher claims that high-school students exercise an
average (mean) of 8 hours per week. (You think that the number is
actually higher.) From a sample of 40 students, you find a mean of
9 hours with a sample standard deviation of 1 hour. Conduct a
hypothesis test using a 5% significance level.
a) What are the null and alternative hypotheses?
b) What is the test statistic?
c) What is the p-value?
d) Do your reject the null hypothesis? Explain...

In the journal Mental Retardation, an article reported
the results of a peer tutoring program to help mildly mentally
retarded children learn to read. In the experiment, Form 2 of the
Gates-MacGintie Reading Test was administered to both an
experimental group and a control group after 6 weeks of
instruction, during which the experimental group received peer
tutoring and the control group did not. For the experimental group
n1 = 30 children, the mean score on the
vocabulary portion of...

A researcher samples 676 observations (from a larger
population). The sample has the following statistics: Mean = 45.16
Standard Deviation = 78 a.) Show that the researcher would fail to
reject ( at a level of significance = .05) the null hypothesis that
the true population mean is equal to 40.0 ( when tested against the
alternative hypothesis that it is NOT equal to 40.0). Suppose that,
if the researcher increased the sample size, the sample statistics
would stay the...

In the journal Mental Retardation, an article reported the
results of a peer tutoring program to help mildly mentally retarded
children learn to read. In the experiment, the mildly retarded
children were randomly divided into two groups: the experimental
group received peer tutoring along with regular instruction, and
the control group received regular instruction with no peer
tutoring. There were n1 = n2 = 36 children in each group. The
Gates-MacGintie Reading Test was given to both groups before
instruction...

In the journal Mental Retardation, an article reported
the results of a peer tutoring program to help mildly mentally
retarded children learn to read. In the experiment, the mildly
retarded children were randomly divided into two groups: the
experimental group received peer tutoring along with regular
instruction, and the control group received regular instruction
with no peer tutoring. There were n1 =
n2 = 30 children in each group. The
Gates-MacGintie Reading Test was given to both groups before
instruction...

To determine whether training in a series of workshops on
creative thinking increases IQ scores, a total of 70 students are
randomly divided into treatment and control groups of 35 each.
After two months of training, the sample mean IQ (–X1) for
the treatment group equals 110, and the sample mean IQ
(–X2) for the control group equals 108. The estimated
standard error equals 1.80.
Question:
Steps:
Calculations or Logic:
Answer:
Using t , test the null hypothesis at the...

1a)
A researcher conducts an independent-measures study to examine
how the brain chemical serotonin is related to aggression. One
sample of rats serves as a control group and receives a placebo
that does not affect normal levels of serotonin. A second sample of
rats, low serotonin group, receives a drug that lowers brain levels
of serotonin. Then, the researcher tests the animals by recording
the number of aggressive responses each of the rats display. See
the data below. Is there...

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