
Concept explainers
For Exercises 1 through 10, follow these steps.
a. State the hypotheses and identify the claim.
b. Find the critical value(s).
c. Compute the test value.
d. Make the decision.
e. Summarize the results.
Use the traditional method of hypothesis testing unless otherwise specified. Assume all assumptions have been met.
1. Traffic Accident Fatalities A traffic safety report indicated that for the 21–24 year age group, 31.58% of traffic fatalities were victims who had used a seat belt. Victims who were not wearing a seat belt accounted for 59.83% of the deaths, and the status of the rest was unknown. A study of 120 randomly selected traffic fatalities in a particular region showed that for this age group, 35 of the victims had used a seat belt, 78 had not, and the status of the rest was unknown. At α = 0.05, is there sufficient evidence that the proportions differ from those in the report?
Source: New York Times Almanac.
(a)

To state: The hypothesis and the claim.
Answer to Problem 11.1.1RE
The null and alternative hypotheses are:
And the claim of the test is the observed proportion is different from the reported proportion.
Explanation of Solution
Given info:
The percentage of death and the observed count corresponding to each reason are provided in the question. The level of significance is
Justification:
The researcher wants to know that whether the proportion of the traffic fatalities corresponding to each reason is different from the reported proportion or not. The null and alternative hypothesis can be defined as:
Null hypothesis:
Alternative hypothesis:
In the provided situation, the claim of the study will be the observed proportion corresponding to each reason is different from the reported proportion.
(b)

The critical value.
Answer to Problem 11.1.1RE
The required critical value is 5.991.
Explanation of Solution
The required critical value is obtained from the provided chi-square table in the textbook. The number of categories is 3.
The degrees of freedom is calculated as:
Therefore, the critical value at
(c)

The value of the test statistic.
Answer to Problem 11.1.1RE
The test statistic value is 1.819.
Explanation of Solution
Calculation:
Software procedure:
Step-by-step procedure to obtain the test statistic using the MINITAB software:
- Enter the data in the Minitab worksheet.
- Go to Stat> Tables> Chi-Square Goodness-of-Fit Test (one variable).
- Specify the “Observed count”, choose the option “Proportions specified by historic count”, and specify the column where the percentage is written.
- Click on OK.
Output using the MINITAB software is given below:
Therefore, the obtained value of the test statistic is 1.819.
(d)

To make: The decision.
Answer to Problem 11.1.1RE
The null hypothesis will not be rejected.
Explanation of Solution
The obtained value of the test statistic is 1.819 and the critical value is 5.991. As the obtained value of the chi-square statistic is less than the critical value, it can be said that there is not enough evidence to reject the null hypothesis at
(e)

To summarize: The results.
Answer to Problem 11.1.1RE
According to the obtained result, the claim of the study is not true.
Explanation of Solution
The null hypothesis is not rejected. On the basis of the obtained result, it can be concluded that the result of the proportion of the traffic fatalities is not different from the reported proportion at
Want to see more full solutions like this?
Chapter 11 Solutions
Connect hosted by ALEKS Access Card 52-Week for Elementary Statistics: A Step by Step Approach
- Exercise 6-6 (Algo) (LO6-3) The director of admissions at Kinzua University in Nova Scotia estimated the distribution of student admissions for the fall semester on the basis of past experience. Admissions Probability 1,100 0.5 1,400 0.4 1,300 0.1 Click here for the Excel Data File Required: What is the expected number of admissions for the fall semester? Compute the variance and the standard deviation of the number of admissions. Note: Round your standard deviation to 2 decimal places.arrow_forward1. Find the mean of the x-values (x-bar) and the mean of the y-values (y-bar) and write/label each here: 2. Label the second row in the table using proper notation; then, complete the table. In the fifth and sixth columns, show the 'products' of what you're multiplying, as well as the answers. X y x minus x-bar y minus y-bar (x minus x-bar)(y minus y-bar) (x minus x-bar)^2 xy 16 20 34 4-2 5 2 3. Write the sums that represents Sxx and Sxy in the table, at the bottom of their respective columns. 4. Find the slope of the Regression line: bi = (simplify your answer) 5. Find the y-intercept of the Regression line, and then write the equation of the Regression line. Show your work. Then, BOX your final answer. Express your line as "y-hat equals...arrow_forwardApply STATA commands & submit the output for each question only when indicated below i. Generate the log of birthweight and family income of children. Name these new variables Ibwght & Ifaminc. Include the output of this code. ii. Apply the command sum with the detail option to the variable faminc. Note: you should find the 25th percentile value, the 50th percentile and the 75th percentile value of faminc from the output - you will need it to answer the next question Include the output of this code. iii. iv. Use the output from part ii of this question to Generate a variable called "high_faminc" that takes a value 1 if faminc is less than or equal to the 25th percentile, it takes the value 2 if faminc is greater than 25th percentile but less than or equal to the 50th percentile, it takes the value 3 if faminc is greater than 50th percentile but less than or equal to the 75th percentile, it takes the value 4 if faminc is greater than the 75th percentile. Include the outcome of this code…arrow_forward
- solve this on paperarrow_forwardApply STATA commands & submit the output for each question only when indicated below i. Apply the command egen to create a variable called "wyd" which is the rowtotal function on variables bwght & faminc. ii. Apply the list command for the first 10 observations to show that the code in part i worked. Include the outcome of this code iii. Apply the egen command to create a new variable called "bwghtsum" using the sum function on variable bwght by the variable high_faminc (Note: need to apply the bysort' statement) iv. Apply the "by high_faminc" statement to find the V. descriptive statistics of bwght and bwghtsum Include the output of this code. Why is there a difference between the standard deviations of bwght and bwghtsum from part iv of this question?arrow_forwardAccording to a health information website, the distribution of adults’ diastolic blood pressure (in millimeters of mercury, mmHg) can be modeled by a normal distribution with mean 70 mmHg and standard deviation 20 mmHg. b. Above what diastolic pressure would classify someone in the highest 1% of blood pressures? Show all calculations used.arrow_forward
- Write STATA codes which will generate the outcomes in the questions & submit the output for each question only when indicated below i. ii. iii. iv. V. Write a code which will allow STATA to go to your favorite folder to access your files. Load the birthweight1.dta dataset from your favorite folder and save it under a different filename to protect data integrity. Call the new dataset babywt.dta (make sure to use the replace option). Verify that it contains 2,998 observations and 8 variables. Include the output of this code. Are there missing observations for variable(s) for the variables called bwght, faminc, cigs? How would you know? (You may use more than one code to show your answer(s)) Include the output of your code (s). Write the definitions of these variables: bwght, faminc, male, white, motheduc,cigs; which of these variables are categorical? [Hint: use the labels of the variables & the browse command] Who is this dataset about? Who can use this dataset to answer what kind of…arrow_forwardApply STATA commands & submit the output for each question only when indicated below İ. ii. iii. iv. V. Apply the command summarize on variables bwght and faminc. What is the average birthweight of babies and family income of the respondents? Include the output of this code. Apply the tab command on the variable called male. How many of the babies and what share of babies are male? Include the output of this code. Find the summary statistics (i.e. use the sum command) of the variables bwght and faminc if the babies are white. Include the output of this code. Find the summary statistics (i.e. use the sum command) of the variables bwght and faminc if the babies are male but not white. Include the output of this code. Using your answers to previous subparts of this question: What is the difference between the average birthweight of a baby who is male and a baby who is male but not white? What can you say anything about the difference in family income of the babies that are male and male…arrow_forwardA public health researcher is studying the impacts of nudge marketing techniques on shoppers vegetablesarrow_forward
- The director of admissions at Kinzua University in Nova Scotia estimated the distribution of student admissions for the fall semester on the basis of past experience. Admissions Probability 1,100 0.5 1,400 0.4 1,300 0.1 Click here for the Excel Data File Required: What is the expected number of admissions for the fall semester? Compute the variance and the standard deviation of the number of admissions. Note: Round your standard deviation to 2 decimal places.arrow_forwardA pollster randomly selected four of 10 available people. Required: How many different groups of 4 are possible? What is the probability that a person is a member of a group? Note: Round your answer to 3 decimal places.arrow_forwardWind Mountain is an archaeological study area located in southwestern New Mexico. Potsherds are broken pieces of prehistoric Native American clay vessels. One type of painted ceramic vessel is called Mimbres classic black-on-white. At three different sites the number of such sherds was counted in local dwelling excavations. Test given. Site I Site II Site III 63 19 60 43 34 21 23 49 51 48 11 15 16 46 26 20 31 Find .arrow_forward
- Glencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw HillCollege Algebra (MindTap Course List)AlgebraISBN:9781305652231Author:R. David Gustafson, Jeff HughesPublisher:Cengage LearningHolt Mcdougal Larson Pre-algebra: Student Edition...AlgebraISBN:9780547587776Author:HOLT MCDOUGALPublisher:HOLT MCDOUGAL



