An economist is studying the job market in denver area neighborhoods. Let x represent the total number of jobs in a given neighborhood, and let y represent the number of entry-level jobs in the same neighborhood. A sample of six Denver neighborhoods Gave the following information (units in hundreds of jobs).
x 15 35 48 28 50 25
y 3 4 7 5 9 3
complete parts (a) through (e), given ∑x=201, ∑y=31, ∑x2=7663, ∑y2=189, ∑xy=1186, and r≈0,901.
a)draw a scatter diagram displaying the data
b) verify the given sums, ∑x, ∑y, ∑x2, ∑y2, ∑xy, and the value of the sample correlation coefficient r. ()round your value for r to three decimal value).
c) find the x-, and y- then find the equation of the least-squares line yˆ=a+bx. (round your answers for x- and y- to two decimal places. round your answers for a and b to three decimal places.)
e)find the value of the coefficient of determination r2. what percentage of the variation in y can be explained by the corresponding variation in x and the least-squares line? what percentage is unexplained? (round your answer for r2 ro three decimal places. round your answers for the percentages to one decimal places.)
f) for a neighborhood with x=37 hundred jobs, how many are predicted to be entry level jobs? (round your answer to two decimal places.)
In: Math
I have Standard Deviation and Mean of 2 sets of data.
Based on the data, how can we infer at the 5% significance level
that the score of individuals in the 4th year is better than the
individuals in 1st year?
| average | 71.29 | 76.98 |
| S.D. | 8.58 | 8.119 |
| Year 1 | Year 4 |
The sample size is 430
In: Math
What distribution should be used to model variance? Why?
In: Math
In: Math
Gentle Ben is a Morgan horse at a Colorado dude ranch. Over the past 8 weeks, a veterinarian took the following glucose readings from this horse (in mg/100 ml).
93 86 83 104 101 108 86 87
The sample mean is x ≈ 93.5. Let x be a random variable representing glucose readings taken from Gentle Ben. We may assume that x has a normal distribution, and we know from past experience that σ = 12.5. The mean glucose level for horses should be μ = 85 mg/100 ml. Do these data indicate that Gentle Ben has an overall average glucose level higher than 85? Use α = 0.05.
Compute the z value of the sample test statistic.
(Round your answer to two decimal places.)
(c) Find (or estimate) the P-value. (Round your answer to
four decimal places.)
(d) Based on your answers in parts (a) to (c), will you reject or
fail to reject the null hypothesis? Are the data statistically
significant at level α?
At the α = 0.05 level, we reject the null hypothesis and conclude the data are statistically significant.
At the α = 0.05 level, we reject the null hypothesis and conclude the data are not statistically significant.
At the α = 0.05 level, we fail to reject the null hypothesis and conclude the data are statistically significant.
At the α = 0.05 level, we fail to reject the null hypothesis and conclude the data are not statistically significant.
In: Math
10. Which of the following research situations would be most likely to use an independent-measures design? – 2pts
a. Examine the development of vocabulary as a group of children mature from age 2 to age 3
b. Examine the long-term effectiveness of a stop-smoking treatment by interviewing subjects 2 months and 6 months after the treatment ends
c. Compare the mathematics skills for 9th -grade boys versus 9th -grade girls
d. Compare the blood-pressure readings before medication and after medication for a group a patients with high blood pressure
11. An independent-measures study comparing two treatment conditions produces a t statistic with df = 18. If the two samples are the same size, how many participants were in each of the samples? – 2pts.
a. 9
b. 10
c. 19
d. 20
12. For which of the following situations would a repeated-measures research design be appropriate? – 2pts
a. Comparing mathematical skills for girls versus boys at age 10
b. Comparing pain tolerance with and without acupuncture needles
c. Comparing self-esteem for students who participate in school athletics versus those who do not
d. Comparing verbal solving skills for science majors versus art majors at a college
13. A researcher plans to conduct a research study comparing two treatment conditions with a total of 20 participants. Which of the following designs would produce 20 scores in each treatment? – 2pts
a. An independent-measures design
b. A repeated-measures design
c. A matched-subjects design
d. All of the other options would produce 20 scores in each treatment.
14. A repeated-measures study uses a total of n = 10 participants to compare two treatment conditions. How many scores are measured in this study, and how many scores are actually used to compute the sample mean and the sample variance? – 2pts
a. 20 measured and 10 used b. 20 measured and 20 used c. 10 measured and 10 used d. 10 measured and 20 used
In: Math
The accompanying data on x = current density (mA/cm2) and y = rate of deposition (µm/min) appeared in an article. Do you agree with the claim by the article's author that "a linear relationship was obtained from the tin-lead rate of deposition as a function of current density"?
| x | 20 | 40 | 60 | 80 |
| y | 0.29 | 1.10 | 1.76 | 2.07 |
Find the value of r2. (Round your answer to
three decimal places.)
r2 =
Explain your reasoning.
The very high value of r2 denies the author's claim.
The very low value of r2 confirms the author's claim.
The very high value of r2 confirms the author's claim.
The very low value of r2 denies the author's claim.
In: Math
|
Consider the following matched samples representing observations before and after an experiment. Assume that the sample differences are normally distributed. Use Table 2. |
| Before | 2.5 | 1.8 | 1.4 | -2.9 | 1.2 | -1.9 | -3.1 | 2.5 |
| After | 2.9 | 3.1 | 3.9 | -1.8 | 0.2 | 0.6 | -2.5 | 2.9 |
Let the difference be defined as Before – After.
| a. |
Construct the competing hypotheses to determine if the experiment increases the magnitude of the observations. |
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|
| b-1. |
Implement the test at a 5% significance level. (Negative value should be indicated by a minus sign. Round all intermediate calculations to at least 4 decimal places and final answer to 2 decimal places.) |
| Test statistic |
| b-2. |
What is the p-value? |
||||||||||
|
| b-3. |
What is the conclusion to the hypothesis test? |
|
We (Click to select)rejectdo not reject H0. At the 5% significance level, We (Click to select)cancannot conclude that the experiment increases the magnitude of the observations. |
| c. | Do the results change if we implement the test at a 1% significance level? | ||||
|
In: Math
You may need to use the appropriate appendix table or technology to answer this question.
The following results come from two independent random samples taken of two populations.
| Sample 1 | Sample 2 |
|---|---|
|
n1 = 50 |
n2 = 25 |
|
x1 = 13.6 |
x2 = 11.6 |
|
σ1 = 2.5 |
σ2 = 3 |
(a)
What is the point estimate of the difference between the two population means? (Use
x1 − x2.)
(b)
Provide a 90% confidence interval for the difference between the two population means. (Use
x1 − x2.
Round your answers to two decimal places.)
to
(c)
Provide a 95% confidence interval for the difference between the two population means. (Use
x1 − x2.
Round your answers to two decimal places.)
to
In: Math
1.
Toll Brothers is a luxury home builder that would like to test the hypothesis that the average size of new homes exceeds 2,400 square feet. A random sample of 36 newly constructed homes had an average of 2,510 square feet. Assume that the standard deviation of the size for all newly constructed homes is 480 square feet. Toll Brothers would like to set α = 0.02. Use the p-value approach to test this hypothesis.
| a. |
0.0838 |
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| b. |
0.01 |
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| c. |
0.05 |
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| d. |
0.1 2. Bananas are sold in bunches at a grocery store and typically consist of 4-8 bananas per bunch. Suppose the weight of these bunches follows a normal distribution with a mean of 3.54 pounds and a standard deviation of 0.63 pounds. The interval around the mean that contains 99.7% of the bunch weights is ________.
|
In: Math
true or false: control charts are a useful tool for tallying the number of defects.
In: Math
ou may need to use the appropriate appendix table or technology to answer this question.
A consumer product testing organization uses a survey of readers to obtain customer satisfaction ratings for the nation's largest supermarkets. Each survey respondent is asked to rate a specified supermarket based on a variety of factors such as: quality of products, selection, value, checkout efficiency, service, and store layout. An overall satisfaction score summarizes the rating for each respondent with 100 meaning the respondent is completely satisfied in terms of all factors. Suppose sample data representative of independent samples of two supermarkets' customers are shown below.
| Supermarket 1 | Supermarket 2 |
|---|---|
|
n1 = 270 |
n2 = 300 |
|
x1 = 82 |
x2 = 81 |
(a)
Formulate the null and alternative hypotheses to test whether there is a difference between the population mean customer satisfaction scores for the two retailers. (Let μ1 = the population mean satisfaction score for Supermarket 1's customers, and let μ2 = the population mean satisfaction score for Supermarket 2's customers. Enter != for ≠ as needed.)
H0:
Ha:
(b)
Assume that experience with the satisfaction rating scale indicates that a population standard deviation of 14 is a reasonable assumption for both retailers. Conduct the hypothesis test.
Calculate the test statistic. (Use
μ1 − μ2.
Round your answer to two decimal places.)
Report the p-value. (Round your answer to four decimal places.)
p-value =
At a 0.05 level of significance what is your conclusion?
Reject H0. There is not sufficient evidence to conclude that the population mean satisfaction scores differ for the two retailers.Reject H0. There is sufficient evidence to conclude that the population mean satisfaction scores differ for the two retailers. Do not reject H0. There is sufficient evidence to conclude that the population mean satisfaction scores differ for the two retailers.Do not reject H0. There is not sufficient evidence to conclude that the population mean satisfaction scores differ for the two retailers.
(c)
Which retailer, if either, appears to have the greater customer satisfaction?
Supermarket 1Supermarket 2 neither
Provide a 95% confidence interval for the difference between the population mean customer satisfaction scores for the two retailers. (Use
x1 − x2.
Round your answers to two decimal places.)
to
In: Math
There are eight different jobs in a printer queue. Each job has a distinct tag which is a string of three upper case letters.
The tags for the eight jobs are: { LPW, QKJ, CDP, USU, BBD, PST, LSA, RHR }
How many different ways are there to order the eight jobs in the queue so that job USU comes somewhere before CDP in the queue (although not necessarily immediately before) and CDP comes somewhere before BBD (again, not necessarily immediately before)?
In: Math
Congratulations you have almost completed biostatistics and have decided since you loved the class so much you want to be a research scientist after you graduate. After applying for several jobs you were able to get your dream job at USF and the only requirement is that you conduct research. Explain in detail the steps you need to take to plan a research project, ranging from planning the question to obtaining a result from a statistical model. Experimental Design and Biostatistics
In: Math
Overproduction of uric acid in the body can be an indication of cell breakdown. This may be an advance indication of illness such as gout, leukemia, or lymphoma.† Over a period of months, an adult male patient has taken fifteen blood tests for uric acid. The mean concentration was x = 5.35 mg/dl. The distribution of uric acid in healthy adult males can be assumed to be normal, with σ = 1.91 mg/dl.
(a) Find a 95% confidence interval for the population mean concentration of uric acid in this patient's blood. What is the margin of error? (Round your answers to two decimal places.) lower limit upper limit margin of error
(b) What conditions are necessary for your calculations? (Select all that apply.)
uniform distribution of uric acid
σ is known
normal distribution of uric acid
n is large
σ is unknown
(d) Find the sample size necessary for a 95% confidence level
with maximal margin of error E = 1.08 for the mean
concentration of uric acid in this patient's blood. (Round your
answer up to the nearest whole number.)
blood tests
In: Math