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# Hypothesis Testing

### Hypothesis Test - 1

Blockbuster began a policy of waiving late fees (sort of!) on DVD rentals a while back. A random sample of ten customers is shown in the file Blockdvd.xls with the number each customer rented when there was a late fee and when there was no late fee. Test at ? = .10 whether the data suggest that the monthly mean number of rentals

### Test the Hypothesis: Eye Exercises and Peripheral Vision

A researcher conducted an experiment to see if specific eye exercises can improve peripheral vision. A random sample of 5 people were rated for peripheral vision on a scale of 1-20, where 9 is considered average and higher scores indicate better peripheral vision. Then they followed the prescribed eye exercise program and were r

### Testing a Hypothesis

Researchers have hypothesized that the proverbial rose-colored glasses might indeed help lessen depression caused by light deprivation. A random sample of 39 people suffering from light deprivation depression were given a depression inventory exam, and it was found that on the scale their average measure was 27 with a standard d

### Critiquing PERT

You decide to introduce the concept of PERT to a business who is struggling with project scheduling. One of the managers of the company tells you the following: "Well, we thought about PERT before actually. The best part about PERT is that it recognizes uncertainty in project time estimation as it is - there is no attempt to

### 30 Insulators Level of Significance: Evaluating Force

An organization thinks that if the electrical insulators break when in use, a short circuit might occur. To test the strength of the insulators, a hard core test will be performed to determine how much force is required to break the insulators. Force is measured by observing the number of pounds of force (lbs.) applied to the

### Testing Research Hypotheses

Please help with the following problem. In playing the Lemonade Stand Game, Bob decreased his price per cup by two cents, from \$.27 per cup to \$.25 per cup. At the .05 level of significance, did net revenue increase? The data for weeks 3 and 4 are presented below; there were 30 observations in each week. Items to compar

### Hypothesis Test: Fitness Camp Glasses

Researchers at the Cornell University Food and Brand Lab conducted an experiment at a fitness camp for adolescents (Wansink & van Ittersum, 2003). Campers were given either a 22-ounce glass that was tall and thin or a 22-ounce glass that was short and wide. Campers with the short glasses tended to pour more soda, milk, or juice

### Choosing a Suitable Hypothesis Test

For each of the following three scenarios, state which hypothesis test you would use from among the four introduced so far: the z test, the single-sample t test, the paired-samples t test, and the independent-samples t test. (Note: In the actual studies described, the researchers did not always use one of these tests, often beca

### Using level of significance

"Lets Go Hamburger Restaurant" does not want to display the nutritional content of its offerings, claiming that only 50% of its customers read them. A consumer group surveyed a random sample of 85 people and asked whether they read the nutritional labels. Of this group, 51 said that they DO read labels. Test the claim that more

### Creating Hypotheses

Assume you are the manager of a paint manufacturing factory. Your company has received complaints from customers that the containers hold less than the amount printed on them. On the other hand, corporate management is concerned that the containers hold more than the standard amount. You assign a statistician to verify these

### T-Statistics Independent Samples

Numeric results for several independent-samples t tests are presented here. Decide whether each test is statistically significant, and report each result in the standard APA format. a. A total of 73 people were studied, 40 in one group and 33 in the other group. The test statistic was calculated as 2.126 for a two-tailed test

### Comparing Outcomes of Two Datasets

1.7 0.7 -0.1 -0.7 -3.5 14.9 3.5 17.1 -7.6 1.6 11.7 6.1 1.1 -4.0 20.9 -9.1 2.1 -1.4 1.4 -0.3 -3.7 -0.8 2.4 12.6 1.9 3.9 0.1 15.4 -0.7 0 You obtain the data shown below for 30 girls with anorexia who were treated with psychodynamic

### Population Mean Waiting Time

a) You are the manager of a fast food restaurant. You want to determine whether the population mean waiting time to place an order has changed in the past month from its previous population mean value of 4.5 minutes. From past experience, you can assume that the population is normally distributed with a population standard dev

### Direction of a Test

10 Test the claim below about the mean of the difference of two populations. Use a t-test for dependant, random samples at the given level of significance with the given statistics. Is the test right-tailed, left-tailed, or two-trailed? Assume the populations are normally distributed. Is the test right-tailed, left-taile

### Uniform distribution of bicycle accidents

A bicycle safety organization claims that fatal bicycle accidents are uniformly distributed throughout the week. The table below shows the day of the week for which 778 randomly selected fatal bicycle accidents occurred. At ? = 0.10, can you reject the claim that the distribution is uniform? Complete parts (a) through (d) bel

### Random Sampling Distribution Test

An automobile manufacturer advertises that the mean petrol consumption of its new hybrid car does not exceed 4.6 litres per 100 km. An independent company decides to test the manufacturer's claim by selecting a random sample of 16 vehicles and measuring the consumption of each. They have found that the petrol consumptions in lit

### Errors and Their Implications

It has been said that from the point of view of the general population, Type I errors are particularly undesirable. This has been used as a justification for setting alpha at such low levels as .05 and .01. Does this make sense? Explain your response. What are the implications of making a Type I error, as compared to those o

### Testing Assumptions.

For its validity, all hypothesis testing depends heavily on the assumption that the sample that is used was drawn using probability sampling techniques. Why is this important? What can you do if you just cannot use a probability sampling technique? (For example, suppose there is no good sampling frame available for the popul

### One-tailed and Two-tailed Tests

You are doing a study examining the effects of studying method on academic achievement. All the students in your study take a course on genetics that lasts for 10 days. One group of students studies 20 minutes a day for 10 days. The second group studies once at the end of the course but for 200 minutes. What is a one-tailed t

### Hypothesis - Tests and Errors

With each hypothesis, indicate whether the appropriate analysis would be a one-tailed test or a two-tailed test and indicate a type I and type II error, given the context of the hypothesis. Hypothesis: 1. The three treatments tested differ in how well they work. 2. Children receiving supportive therapy will get worse ov

### Hypothesis Testing: One Sample Inference

Diabetes Plasma-Glucose levels are used to determine the presence of diabetes. Suppose the mean in (plasma-glucose) concentration (mg/dL) in 35 to 44-year-olds is 4.86 with standard deviation = 0.54. A study of 100 sedentary people in this group is planned to test whether they have a higher or lower level of plasma glucose t

### Statistics - Critical Values

Write the claim mathematically and identify Hₒ and Hₐ. (b) Find the critical value(s) and identify the rejection region(s). (c) Find the standardized test statistic. (d) decide whether to reject or fail to reject the null hypothesis. A medical researcher says that at least 24% of adults are smokers. In a random sample o

### Case 3: Grocery4You.com

e-grocers are companies that sells groceries over the internet. Customers open an online account, enter their orders, pay by credit card or debit card, and receive deliveries by truck. Several businesses think that it is means of convenience for busy customers who have no or very little time to go to a grocery store, buy groce

### Hypothesis Testing Exercise

M&Ms® Project Part 5 Test the hypothesis (α = 0.05) that the population proportions of red and brown are equal (pred = pbrown). You are testing if their proportions are equal to one another, NOT if they are equal to one another AND equal to 13%. NOTE: These are NOT independent samples, but we will use this approach any

### Concepts and properties of the hypothesis testing.

1. a) What is a hypothesis? Specifically, is it a statement about the population or the sample? b) What is the purpose of hypothesis testing? c) How is the role of the null hypothesis different from that of the research (alternative) hypothesis? d) Provide an example of a hypothesis test you could conduct at work

### Finding the critical value of a left-tailed t-test

Find the critical value(s) for a left-tailed test for a population variance, sample size n = 9, and level of significance = 0.01 Find the critical value(s). (Round to three decimal places as needed)

### Self-Reported & Measured Male Heights

As part of the National Health and Nutrition Examination Survey, the Department of Health and Human Services obtained self-reported heights and measured heights for males aged 12-16. All measurement is in inches. Listed below are sample results. a. Is there sufficient evidence to support the claim that there is a difference b

### Sample proportion question

When an election for political office takes place, the television networks cancel regular programming and instead provide election coverage. When the ballots are counted, the results are reported. However, for important offices such as president or senator in large states, the networks actively compete to see which will be the f

### Comparing p value method, hypothesis test and confidence interval.

A student of the author surveyed her friends and found that among 20 males, 4 smoke and among 30 female friends, 6 smoke. Give two reasons why these results should not be used for a hypothesis test of the claim that the proportions of male smokers and female smokers are equal. Given a simple random sample of men and a simple ra

### Statistics Enriching and Representing the Results of a Study

Based on what we know about statistics and using a real example, how do you believe statistics can enrich and represent the results of a study? How can statistics be used to misrepresent the results of a study? With these thoughts in mind: Write an example, a description of how you believe statistics can enrich and repres