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Hypothesis Testing

Statistics Concepts and Calculations

16-22. The following sample data were obtained from three populations where the variances were not equal, and you wish to compare the populations. Sample 1 Sample 2 Sample 3 21 15 38 29 17 40 35 22 44 45 27 51 56 31 53 71 1. State the null hypothesis. 2. Using the .01 level of risk, state the decision rule. 3. C

Significance testing in 5 different situations

1. Suppose you want to test the claim that the population mean(u) is < or equal to 25.6. Given a sample size of n=44 and a level of significance of 0.05, when should you reject the null hypothesis? 2. Given the null hypothesis: population mean = 25 and the alternative hypothesis population mean not equal to 25, and P=0.041

One-Tailed Tests for Population Standard Deviation of Mean Income of Teachers

Past records suggest that the mean annual income, u1, of teachers in state of Utah is greater than or equal to the mean annual income, u2, of teachers in Oregon. In a current study, a random sample of 10 teachers from Utah and an independent random sample of 10 teachers from Oregon have been asked to report their mean annual inc

6 Hypothesis Testing Questions

Problem 14.3 The marketing manager of a large supermarket chain would like to determine the effect of shelf space on the sales of pet food. A random sample of 12 equal-sized stores is selected, with the following results: (see attachment for clearer tables) Store Shelf Space X (Feet) Weekly Sales Y (Hundreds of Dollars

Statistics, Research and Evaluation

1. Determine what would happen to your critical value (Z) if you were to change the level of significance (a) from .05 to .1 in a two tailed hypothesis test. 2. Why would the critical value change in the way you predict? 3. What does this suggest about the trade offs between Type 1 and Type II errors? Please give s

Hypothesis Test: Two-tailed Test of Difference Between Means

According to the historical data, the life expectancy in Argentina is equal to the life expectancy in Bolivia. A new study has been made to see whether this has changed. Records of 295 individuals from Argentina who died recently are selected at random. The 295 individuals lived an average of 74.8 years with a standard deviat

Significance Level: Time Spent at Desktop

10. The manager of a computer software company wishes to study the number of hours senior executives spend at their desktop computers by type of industry. The manager selected a sample of five executives from each of three industries. At the .05 significance level, can she conclude there is a difference in the mean number of hou

Statistics problems dealing with probability

1. All Seasons Plumbing has two service trucks which frequently break down. If the probability the first truck is available is .75, the probability the second truck is available is .50, and the probability that both trucks are available is .30, what is the probability neither truck is available? 2. Textbook authors and publi

Testing proportions

The manufacturer of Feel Better aspirin advertises that 60% of pediatricians recommend Feel Better for children under twelve. Safe and Sound, a rival manufacturer, surveyed 650 pediatricians and found that only 357 of them recommended Feel Better for children under twelve. Safe and Sound now claims that Feel Better's advertising

Hypothesis testing

A researcher claims that the average age of a woman before he has her first child is now greater than it was in 1990. In 1990, that average age was 26.4 years. She obtains a random sample of 40 women who all recently gave birth to their first child, and calculates their mean age to be 27.1 years. From another recent study, she

Testing a hypothesis: emergency response

Suppose a candidate running for sheriff claims that she will reduce the average speed of emergency response to less than 3o minutes. (30 minutes is thought to be the average response time with the current sheriff,) There are no past records so the actual standard deviation of such response times cannot be determined. Thanks to t

Hypothesis testing

The NCAA requires colleges to report the graduation rates of their athletes. At one large university 70.7% of all students who entered between 1989 and 1991 graduated within 6 years. 95 of the 147 students who entered with athletic scholarships graduated. Consider these 95 as a sample of the athletes who will be admitted under p

Research and Evaluation

What are some of the ethical issues we encounter in using hypothesis testing? How might we discover if a researcher has compromised ethics in reporting hypothesis testing results? When and how would we use hypothesis testing at our place of employment, or in politics?

State the hypotheses, the direction, the p-value, the decision and the conclusion

Production process is considered to be under control if the machine parts it makes have a mean length of 35.50 mm with a standard deviation of 0.45 mm. Whether or not the process is under control is decided each morning by a quality control engineer who bases his decision on a random sample of size 36. Should he ask for an adjus

Hypothesis

The college librarian believes that more than 60% of the books checked out by students were fictional material. In a random sample of 1000 students who checked books out in the last year, 650 checked out fictional material. What can one conclude about the librarian's hypothesis at a level of significance of .05?

Hypothesis problem

In a speech to the Chamber of Commerce, a city councilman claims that in his city less than 15% of the adult male population is unemployed. A subsequent check taken by a newspaper reporter showed that among 300 adult males polled, 36 were unemployed. Is there sufficient evidence to support the councilman's claim at a level of si

Hypothesis

An instructor thinks that math majors can write and debug computer programs faster than business majors. A sample of 12 math majors took an average of 36 minutes to write a specific program and debug it; a sample of 18 business majors took an average of 39 minutes. The standard deviations were 4 minutes and 9 minutes, respective

Hypothesis

A medical researcher wishes to see whether the pulse rates of smokers are higher than the pulse rates of nonsmokers. Samples of 100 smokers and 100 nonsmokers are selected. The results are shown here. Can the researcher conclude, at (confidence interval) =0.05 that smokers have higher pulse rates than nonsmokers?

Problem Set: Hypothesis Test, Test Statistics, Two-Sample t-tests

1. Identify the null hypothesis and the alternative hypothesis. A researcher claims that 62% of voters favor gun control. 2. Assume that the data has a normal distribution and the number of observations is greater than fifty. Find the critical z value used to test a null hypothesis. alpha = 0.05 for a left-tailed test.

Two Hypothesis tests questions involving pressure and the bounce of tennis balls

Chapter 12 problem 11 A machine is set to produce tennis balls so the mean bounce is 36 inches when the ball is dropped from a platform of a certain height The supervisor suspects that the mean bounce has changed and is less than 36 inches. As an experiment 42 balls were dropped from the platform and the mean height of the bo

Hypothesis Test of Paired Samples: Absenteeism in a Large Manufacturing Company

Lester Hollar is Vice President for Human Resources for a large manufacturing company. In recent years he has noticed an increase in absenteeism that he thinks is related to the general health of the employees. Four years ago, in an attempt to improve the situation, he began a fitness program in which employees exercise during

Test of means

Team A did OK, once some adjustments were made to their offense and defense. However, Coach Mi is not convinced that his team is evenly matched to other teams in size. So he contacts Coach Lee of Team B to get the scoop on his team, and this is what he comes up with... Population Team A Team B Sample size n1 = 32 n2 =

Statistics and Hypothesis

1) Flammability tests were conducted on children's sleepwear. The vertical semi restrained test was used, in which pieces of fabric were burned under controlled conditions. After the burning stopped, the length of the charred portion was measured and recorded. The same fabric samples were tested at five different laboratories

Hypothesis testing

A sample of 100 orders revealed that 82 were delivered within the promised time. At the 0.10 significance level, can we conclude that less than 90% of the orders are delivered in less than 10 minutes? What is the Null Hypothesis, Alternate Hypothesis, Alpha, Choice of test, Critical Value of test? Show computations. Interpret f

Research Questions

1. The purpose of an operational definition is to: A. assign numerical values to variables B. specify how a variable will be defined and measured C. state the expected relationship between variables under investigation D. designate the overall plan by which research will be conducted 2. The independent variable (s) in

Male Pay versus Female Pay

According to 1972 article in a national newspaper the starting salaries at a certain national bank showed that on average males were paid more than females. The results are based on a random sample of males and females starting at this bank. a) Can we conclude that the starting salary for males are higher than for females at

Test of hypothesis for proprtions

(see attached) A sample of 200 observations from the population indicated that X1 is 170. A sample of 150 observations from the second population revealed X2 to be 110. Use the .05 significance level to test the hypothesis. A. state the decision rule B. compute the pooled proportion C. compu