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For each of the following hypothesis testing scenarios, indicate whether or not the appropriate hypothesis test would be about a difference in population means. If not, explain why not. Scenario 1: The international polling organization Ipsos reported data from a survey of 2,000 randomly selected Canadians who carry debit cards (Canadian Account Habits Survey, July 24,2006 ). Participants in this survey were asked what they considered the minimum purchase amount for which it would be acceptable to use a debit card. You would like to determine if there is convincing evidence that the mean minimum purchase amount for which Canadians consider the use of a debit card to be acceptable is less than \(\$ 10\). Scenario 2: Each person in a random sample of 247 male working adults and a random sample of 253 female working adults living in Calgary, Canada, was asked how long, in minutes, his or her typical daily commute was ("Calgary Herald Traffic Study," Ipsos, September 17,2005 ). You would like to determine if there is convincing evidence that the mean commute times differ for male workers and female workers. Scenario 3: A hotel chain is interested in evaluating reservation processes. Guests can reserve a room using either a telephone system or an online system. Independent random samples of 80 guests who reserved a room by phone and 60 guests who reserved a room online were selected. Of those who reserved by phone, 57 reported that they were satisfied with the reservation process. Of those who reserved online, 50 reported that they were satisfied. You would like to determine if it reasonable to conclude that the proportion who are satisfied is higher for those who reserve a room online.

Short Answer

Expert verified
Scenario 1: No, it's a test of a single population mean. Scenario 2: Yes, it's a test of a difference in population means. Scenario 3: No, it's a test of a difference in population proportions.

Step by step solution

01

Analyze Scenario 1

For the first scenario, it's not about differences in population means, but rather determining whether the mean of a single population is less than a certain value (\(\$10\)). So, it does not match a difference in population means hypothesis.
02

Analyze Scenario 2

In the second scenario, it is about the difference in the mean commute times for two populations (male workers and female workers). So, this matches the premise of a hypothesis test about a difference in population means.
03

Analyze Scenario 3

In the third scenario, the hypothesis being tested is whether there is a difference in proportions (guests satisfied with the telephone reservation process vs. guests satisfied with the online reservation process), not means. As such, this is not about a difference in population means.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Population Means
When we talk about population means, we refer to the average value of a particular measurement in a large group of people or observations. Understanding the population mean is pivotal in hypothesis testing, as it allows researchers to make informed decisions based on sample data.

In hypothesis testing scenarios, comparing population means involves several steps:
  • State the null and alternative hypotheses. Typically, the null hypothesis claims that there is no difference in the means, while the alternative hypothesis suggests a difference exists.
  • Collect sample data and calculate the sample means.
  • Determine the statistical significance of the difference between sample means using a test statistic. Commonly used tests for this include the t-test for comparing two means.
  • Make a conclusion based on the p-value obtained from the test statistic, whether to reject or fail to reject the null hypothesis.
Scenario 2 from the exercise above is a perfect example, where we compare the average commute times of male and female workers to see if they are statistically different.
Survey Data Analysis
Survey data analysis is often used in research to collect data from a sample of individuals that represent a larger population. Surveys are valuable tools for hypothesis testing as they help gather information on people's behaviors, opinions, or characteristics.

There are several steps involved in performing a survey data analysis:
  • Designing the survey, ensuring questions are clear and unbiased.
  • Conducting the survey to gather data from the sample group.
  • Cleaning and preparing the data for analysis, which involves checking for errors or missing values.
  • Analyzing the data by calculating descriptive statistics such as means, medians, and proportions.
  • Performing inferential statistics to make generalizations about the population, which can include hypothesis testing.
Survey data was pivotal in all three scenarios from the original exercise. For instance, Scenario 1 used survey data to evaluate Canadian's acceptance of debit card usage for low purchase amounts.
Proportion Comparison
Proportion comparison is a statistical method used to evaluate whether one proportion is different from another. This is particularly useful when examining data from separate groups or categories, looking at binary outcomes (such as satisfaction vs. dissatisfaction).

During proportion comparison, the following steps are taken:
  • Formulate the null hypothesis, which typically states there is no difference between the proportions of the groups being compared.
  • Gather data and calculate the sample proportions.
  • Employ a statistical test, such as the z-test for proportions, to determine if observed differences are statistically significant.
  • Analyze the p-value to decide whether to reject the null hypothesis, indicating a significant difference in proportions.
In Scenario 3 from the exercise, the comparison was between two proportions: the satisfaction levels of guests reserving through phone vs. online. This illustrates the application of proportion comparison, where the interest lies in determining if the proportion of satisfied guests differs between the two reservation methods.

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Most popular questions from this chapter

Some people believe that talking on a cell phone while driving slows reaction time, increasing the risk of accidents. The study described in the paper "A Comparison of the Cell Phone Driver and the Drunk Driver" (Human Factors [2006]: \(381-391\) ) investigated the braking reaction time of people driving in a driving simulator. Drivers followed a pace car in the simulator, and when the pace car's brake lights came on, the drivers were supposed to step on the brake. The time between the pace car brake lights coming on and the driver stepping on the brake was measured. Two samples of 40 drivers participated in the study. The 40 people in one sample used a cell phone while driving. The 40 people in the second sample drank a mixture of orange juice and alcohol in an amount calculated to achieve a blood alcohol level of \(0.08 \%\) (a value considered legally drunk in most states). For the cell phone sample, the mean braking reaction time was 779 milliseconds and the standard deviation was 209 milliseconds. For the alcohol sample, the mean breaking reaction time was 849 milliseconds and the standard deviation was \(228 .\) Is there convincing evidence that the mean braking reaction time is different for the population of drivers talking on a cell phone and the population of drivers who have a blood alcohol level of \(0.08 \%\) ? For purposes of this exercise, you can assume that the two samples are representative of the two populations of interest.

The paper "Effects of Fast-Food Consumption on Energy Intake and Diet Quality Among Children in a National Household Survey" (Pediatrics [2004]: \(112-118\) ) investigated the effect of fast-food consumption on other dietary variables. For a representative sample of 663 teens who reported that they did not eat fast food during a typical day, the mean daily calorie intake was 2,258 and the sample standard deviation was \(1,519 .\) For a representative sample of 413 teens who reported that they did eat fast food on a typical day, the mean calorie intake was 2,637 and the standard deviation was \(1,138 .\) Use the given information and a \(95 \%\) confidence interval to estimate the difference in mean daily calorie intake for teens who do eat fast food on a typical day and those who do not.

Do children diagnosed with attention deficit/ hyperactivity disorder (ADHD) have smaller brains than children without this condition? This question was the topic of a research study described in the paper "Developmental Trajectories of Brain Volume Abnormalities in Children and Adolescents with Attention Deficit/Hyperactivity Disorder" (journal of the American Medical Association [2002]: \(1740-\) 1747). Brain scans were completed for a representative sample of 152 children with ADHD and a representative sample of 139 children without ADHD. Summary values for total cerebral volume (in milliliters) are given in the following table: $$ \begin{array}{lccc} & n & \bar{x} & s \\ \hline \text { Children with ADHD } & 152 & 1,059.4 & 117.5 \\ \text { Children Without ADHD } & 139 & 1,104.5 & 111.3 \end{array} $$ Use a \(95 \%\) confidence interval to estimate the differ- ence in mean brain volume for children with and without ADHD.

Descriptions of four studies are given. In each of the studies, the two populations of interest are the students at a particular university who live on campus and the students who live off campus. Which of these studies have samples that are independently selected? Study 1: To determine if there is evidence that the mean amount of money spent on food each month differs for the two populations, a random sample of 45 students who live on campus and a random sample of 50 students who live off campus are selected. Study 2: To determine if the mean number of hours spent studying differs for the two populations, a random sample students who live on campus is selected. Each student in this sample is asked how many hours he or she spend working each week. For each of these students who live on campus, a student who lives off campus and who works the same number of hours per week is identified and included in the sample of students who live off campus. Study 3: To determine if the mean number of hours worked per week differs for the two populations, a random sample of students who live on campus and who have a brother or sister who also attends the university but who lives off campus is selected. The sibling who lives on campus is included in the on campus sample, and the sibling who lives off campus is included in the off- campus sample. Study 4: To determine if the mean amount spent on textbooks differs for the two populations, a random sample of students who live on campus is selected. A separate random sample of the same size is selected from the population of students who live off campus.

For each of the following hypothesis testing scenarios, indicate whether or not the appropriate hypothesis test would be for a difference in population means. If not, explain why not. Scenario 1: The authors of the paper "Adolescents and MP3 Players: Too Many Risks, Too Few Precautions" (Pediatrics [2009]: e953-e958) studied independent random samples of 764 Dutch boys and 748 Dutch girls ages 12 to \(19 .\) Of the boys, 397 reported that they almost always listen to music at a high volume setting. Of the girls, 331 reported listening to music at a high volume setting. You would like to determine if there is convincing evidence that the proportion of Dutch boys who listen to music at high volume is greater than this proportion for Dutch girls. Scenario 2: The report "Highest Paying Jobs for \(2009-10\) Bachelor's Degree Graduates" (National Association of Colleges and Employers, February 2010 ) states that the mean yearly salary offer for students graduating with accounting degrees in 2010 is \(\$ 48,722\). A random sample of 50 accounting graduates at a large university resulted in a mean offer of \(\$ 49,850\) and a standard deviation of \(\$ 3,300\). You would like to determine if there is strong support for the claim that the mean salary offer for accounting graduates of this university is higher than the 2010 national average of \(\$ 48,722\). Scenario 3: Each person in a random sample of 228 male teenagers and a random sample of 306 female teenagers was asked how many hours he or she spent online in a typical week (Ipsos, January 25,2006 ). The sample mean and standard deviation were 15.1 hours and 11.4 hours for males and 14.1 and 11.8 for females. You would like to determine if there is convincing evidence that the mean number of hours spent online in a typical week is greater for male teenagers than for female teenagers.

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