Assumptions of t-test and z-test
What sufficient assumptions are necessary to be able to utilize a z test or a t test?
What sufficient assumptions are necessary to be able to utilize a z test or a t test?
A researcher tests the hearing acuity of a group of seniors one week before and one week after an operation. He hopes to show that the seniors hear better after the operation than before. (The higher the score on this test the poorer the hearing). An individual is represented by (X,Y) where X = score before operation and Y = sco
Work through a t-test to compare the means of two groups of data. One possible example is to compare the tenure of females to the tenure of males. Ensure that you begin by stating the null and alternative hypotheses. Your final answer should point out if the null is confirmed or rejected and why. Please show as much work as poss
Work through a t-test to compare the means of two groups of data. One possible example is to compare the tenure of females to the tenure of males. Begin by stating the null and alternative hypotheses. Point out if the null is confirmed or rejected and why. Work through a chi-square test to compare the expected and observed f
Please help answer the following question. Why is a t-statistic as opposed to a z-statistic used to test small samples? Does the choice of test statistic alter how you employ the 5-step hypothesis testing procedure? When testing two populations with small sample sizes, do both sample sizes have to be the same size?
Click on the link for Table 1 (Standard normal distribution-Z). You will see the z -distributions and t-distributions. I would like you to see the difference in the two. Say we have a test statistic of 1.50. We can plug in our numbers to compare how a z-distribution will look compared to a t-distribution. For Tables 1 click on
Please help with the following problems. Provide step by step calculations and diagrams. a. What is the difference in appearance between a t-distribution and a z-distribution? Why do they have slightly different appearances? b. When do we use a t-distribution rather than a z-distribution?
9.56) The mean length of imprisonment for motor-vehicle theft offenders in Australia is 16.7 months. One hundred randomly selected motor-vehicle theft offenders in Sydney, Australia, had a mean length of imprisonment of 17.8 months. At the 5% significance level, do the data provide sufficient evidence to conclude that the mean
1. Give the formula for the appropriate test statistic, if any, for the following hypothesis testing situations {see attachment} 2. A federal agency responsible for enforcing laws concerning weights and measures routinely inspects packages to determine whether the weight of the contents is at least as great as that advertised
Please explain & show why you use formula you use. Find the critical t alpha/2 assuming the population is normally distributed, the confidence level is 95%, n=101 and sigma is unknown. The answer is 1.984-I'm having trouble with the large n. I don't have a TI-83 calculator. My book stops @ 29 then just says large z number
Refer to the OECD data in the attached EXCEL file, which reports information on census, economic, and business data for 29 countries. Conduct a hypothesis to determine if the mean number of people employed was less than 20,000. (Remember the data is reported in thousands, so the actual number employed is 20,000,000) Use the .
Problems 4.9, 4.12, 4.13, 4.20 from the attached tasks.
The self-help skill teaching for the primary parents of a random sample of families with mentally retarded children before and after training program. Before 07 06 10 16 08 13 08 14 After 11 14 16 17 09 15 09 17 Based on this information, can you conclude that the training program is effective?
A sample of scores on an examination given to both males and females in QNT 540 are: Males 72, 69, 98, 66, 85, 76, 79, 80, and 77 Females 81, 67, 90, 78, 81, 80, and 76 At the .01 level of significance, is the mean grade of the female students higher than that of the males?
A sample of scores on an examination given to both males and females in MAT 560 is: Males 72, 69, 98, 66, 85, 76, 79, 80, and 77 Females 81, 67, 90, 78, 81, 80, and 76 At the .01 level of significance, is the mean grade of the female students higher than that of the males?
Employer A states the average number of days missed in a year by each staff member is 4.0. Office personnel randomly sampled a portion of their attendance records to determine if this claim was accurate. For the previous year, the following data was obtained from the sample group, regarding absences for that year: 4, 4, 3, 2,
A recent report from the American Medical Association claims that for the first time in ten years, the average salary of psychiatrists was greater than $190,000 with a standard deviation of $27,000. What is the null hypothesis for his claim? The Eagle Ridge Contractors Association claims the average price of a home in their
Backfat thickness is a variable used in evaluating the quality of market hogs. An animal scientist measured backfat thickness (cm) on hogs raised on two different diets, with the following results (see attachment): Diet 1 Diet 2 _ X 3.49 3.05 Sx 0.40 0.40
Please see attached information table. Questions to be answered: 1. Given the information on the table, test the hypothesis that the mean is equal to two. 2. State the hypothesis to be tested, the decision rule, the test statistic and the decision. 3. Briefly describe what "skewness" measures.
Experience raising New Jersey Red chickens revealed the average weight of the chickens at age 5 months to be 4.35 lbs. The weights are normally distributed. In an effort to increase their weight, a special additive was mixed with the chicken feed. The subsequent weights of a sample of five-month-old chickens were (in pounds
The makers of Bounce Back glass backboards for basketball gymnasiums have claimed that their board is at least as durable, on the average, as the leading backboard made by Swoosh Company. Products Testing Services of Des Moines, Iowa, was hired to verify this claim. It selected a random sample of 50 backboards of each type and s
In this solution SPSS output tables are provided. The analysis is an independent samples t-test for comparing two population means. The solution gives detailed interpretation of the SPSS computer output.
Find the percentages of the Student's t-distribution that lies between the following values: a. df = 12 and t ranges from -1.36 to 2.68 b. df = 15 and t ranges from -1.75 to 2.95.
For part a, give an example of a situation that fits a Z-test and explain why your example fits the Z-test. You may not use any example that was published in the textbook, the Statistics Discussions conference or the About the Lesson conference. Then, for part b, make appropriate changes to your example, so that a t-test woul
Ten people agree to take part in an experiment designed to determine whether a persons weight differs between morning & evening. Each person is weighed last thing at night & first thing in the morning, wearing the same clothes. The results, giving weights in kilogrammes are below. weight 1 2 3 4 5 6 7 8
Experience raising New Jersey Red chickens revealed the mean weight of the chickens at five months is 4.35 pounds. The weights follow the normal distribution. In an effort to increase their weight, a special additive is added to the chicken feed. The subsequent weights of a sample of five-month-old chickens were (in pounds): 4.
The email usage for two different plants of a large company was compared at level of significance 0.05. A sample of 50 employees was selected at each plant. The mean number of email messages sent per employee for one plant was 15.5 per week and the standard deviation was 5.0. For the other plant, the mean was 18.4 and the stan
The two different formulas for the t test are for which two different types of problems? a. the samples are dependent or the samples are independent b. the variances are assumed to be equal or unequal c. the samples are both large or both small d. the populations are normally distributed or skewed
John makes a mark on a straight stick that is 1 meter in length; you assign a uniform distribution to the location of the mark(uniform over the entire length of the stick). John cuts the stick at that mark, making two sticks. John then takes the larger stick and makes a mark on it; you assign a uniform distribution to the loc
The data in the table that follows was collected by a large car manufacturer concerning a new prototype car called the CIELO. Thirty carefully selected respondents were shown the car and fully briefed about its capabilities. Here is the data, which includes age (intervally scaled), sex (nominal), social status (interval scale ra