Question

A researcher wished to compare the average daily hotel room
rates between San Francisco and Los Angeles. The researcher
obtained an SRS of 15 hotels in downtown San Francisco and found
the sample mean x1=$156 , with a standard deviation s1= $15 . The
researcher also obtained an independent SRS of 10 hotels in
downtown Los Angeles and found the sample mean x2= $143, with a
standard deviation s2=$10.

Let 1 and 2 represent the mean cost of the populations of all
hotels in these cities, respectively. Assume the two-sample t
procedures are safe to use, i.e. Unequal Variances.

1.Suppose the researcher had wished to test the hypotheses H0 :
µ1 = µ2 vs. Ha : µ1 ≠ µ2 at the

5% significance level (i.e., α = 0.05). The numerical value of the
two-sample t statistic is?

2. P value?

3.What are your statistical conclusion and its interpretation? Use significance level, α = 0.05 (or 5%).

4.Based on your P-value and conclusion in (b) and (c), will you
conclude that a 99% confidence

interval for µ1 - µ2 includes the value 0? Explain.

Answer #1

1)

2)

df= 22.993~23

p value = 2*p(t>2.6) = 0.016

c)

d)

Since null hypothesis is rejected so we can say that confidence interval for µ1 - µ2 does not contain 0.

A researcher used an independent sample t test to compare two
treatment conditions. He wanted to test whether there is a
significant difference between two treatments. Following data were
obtained:
Treatment one group: # of participants = 12, sample mean = 55,
sample standard dev (s) = 2.83
Treatment two group: # of participants = 12, sample mean = 52,
sample standard dev (s) = 2.00
Use 5% significance level.
Assume µ1
and µ2 are the population means for group one
and...

A researcher used an independent sample t test to
compare two treatment conditions. He wanted to test whether there
is a significant difference between two treatments. Following data
were obtained:
Treatment one group: # of participants = 12, sample
mean = 55, sample standard dev (s) = 2.83
Treatment two group: # of participants = 12, sample
mean = 52, sample standard dev (s) = 2.00
Use 5% significance level. Assume µ1
and µ2 are the population means for group...

For each of the following two-samples t-tests (problems
1-6): (a) Determine if a F test for the ratio of two variances is
appropriate to calculate for the context. If it is appropriate,
conduct the analysis and report the result. Include what
statistical conclusion you should draw from the analysis (i.e.,
whether you should conduct a pooled-variance t-test or an
unequal-variances t-test). (b) Identify the most appropriate t-test
to conduct for the situation/data given. Don’t forget to consider
if the context...

Question 21
Suppose a health insurance company is interested in carrying out
an investigation as to the annual expenditures per household on
their healthcare costs. In order to most accurately report their
figures, the company decides to ensure “virtual certainty” about
their estimates by using a Z value of 3.0 for their calculations.
The company conducts a SRS of 843 households and determines the
sample average household expenditures on healthcare is
$43,257.00.
A) Assume the company uses a σ=$879.00. Calculate...

Question 6
An investigator is looking at the relationship between
periodontal disease and the onset of hypertension. Suppose the
investigator decides to look at height as a variable that may
confound the relationship between exposure and case status in his
study. After collecting information about the height of each
participant, he assembles a database that approximates height with
the normal distribution.
A) Assuming the mean of the distribution is 176.2 cm with a
standard deviation of 17.5 cm, what are...

1. For a pair of sample x- and y-values, what is the difference
between the observed value of y and the predicted value of y? a) An
outlier b) The explanatory variable c) A residual d) The response
variable
2. Which of the following statements is false:
a) The correlation coefficient is unitless. b) A correlation
coefficient of 0.62 suggests a stronger correlation than a
correlation coefficient of -0.82. c) The correlation coefficient,
r, is always between -1 and 1....

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