Explore BrainMass

Student's t-Test

Significance of the mean difference

Duplicate readings, using two separate instruments, were obtained on ten samples. What is the tabular value of the statistic used to determine the significance of the mean difference at the .05 level of probability?

Hypothesis Testing of Mean: Waiting time for Lunch

A fast food chain restaurant chain claims that lunch will be served within nine minutes of placing your order, or it is free. A sample of eight customers revealed the following waiting times in minutes: 10.1 9.3 9.2 10.2 9.3 9.6 9.4 8.8 At the .01 significance level, can we conclude that the waiting time for lunch exc

Independent samples, pooled estimate of variance

What are independent samples? What is a pooled estimate of variance and why do you need to calculate it? When do you use a dependent versus an independent sample t test? Which is the more powerful t test? What are the assumptions of the independent t test? What are the mechanics of conducting an independent samples t test?

P-Value for 0.01 Level One-tail Test

In a study by Web Criteria, it took an average of 2.1 minutes to locate information and buy products on the Delta Airlines website, compared to an average of 2.7 minutes on the British Airways site. Assume that data file XR11012 contains the times (in minutes) required during visits to the two websites. In a suitable one-tail te

Independent Sample t Test..

Pooled-Variances t-Test for (µ1 - µ2), Population Variances Unknown but Assumed Equal t-Test: Two-Sample Assuming Equal Variances Format 1 Format 2 Mean 6 8.166666667 Variance 9.777777778 11.06060606 Observations 10 12 Pooled Variance 10.48333333 Hypothesized Mean Differe

Students t test for mean are given

SEE ATTACHED FILE - Student t Distribution - Null and Alternative Hypotheses NOTE: Please use an Excel spreadsheet for response. Please do not just provide the answers but show in complete detail how you arrived at the answers, step-by-step, from the beginning to the end of the solution. (10.2)

What is the Test Value: new drug effectiveness between women and men

A pharmaceutical company is testing the effectiveness of a new drug for lowering cholesterol. As part of this trial they wish to determine whether there is a difference between the effectiveness for women and for men. At a=5, what is the test value? ................................Women..........Men

Assessing Critical Region: Computer Mouse Example

An average computer mouse inspector can inspect 50 mice per hour. The 48 computer mice inspectors at a particular factory can only insppect 46 mice per hour with a standard deviation of 10. At alpha = 0.025 does the company have reason to believe that these inspectors are slower than average? (Answer yes or no, the answer an

Difference for t test for independent means & correlated t test

What is the difference between a t test for independent means and a correlated t test? If a production manager wanted to determine whether or not the first shift was processing more widgets than the second shift, what type of statistical process would be used?

Hypothesis Testing: Two sample Z & t test

Please see attached files. "Salaries" and instruction below. Large Sample Case Select the Tools pull-down menu Choose Data Analysis When Data Analysis dialog box appears: Choose z-Test:Two Sample for Means Click Ok When the z-Test: Two Sample for Means dialog box appears: Enter B1:B115 in the Variable 1 Range box

Create a real world situationt Tests for Independent and Related Samples

Create a real-world situation or problem that could be addressed using an independent- or related-samples t test. Create this situation or problem, that clearly identify the independent and dependent variables to study; explain whether an independent-samples or related samples t test is most appropriate and why; generate the st

Calculate T distribution with degrees of freedom

T distribution Use the calculator provided to solve the following problems. ? Consider a t distribution with 21 degrees of freedom. Compute P (-1.49 < t < 1.49). Round your answer to at least three decimal places. ? Consider a t distribution with 3 degrees of freedom. Find the value of such that P (t <=c) = 0.10 . Round yo

Null Hypothesis

For the below exercise (a) State the null hypothesis and the alternate hypothesis. (b) State the decision rule. (c) Compute the value of the test statistic. (d) What is your decision regarding H0? (e) What is the p-value? Interpret it. 1. The manufacturer of the X-15 steel-belted radial truck tire claims that the mean mileage

Statistics: Time to solve Duncker (1945) problem to mount a candle on a wall

20. In a classic study of problem solving, Duncker (1945) asked participant to mount a candle on a wall in an upright position so that it would burn normally. One group was given a candle, a book of matches, and a box of tacks. A second group was given the same items, except that the tacks and the box were presented separately

Statistics: Formulas for the stroke v zip code data; what is the IV and the DV.

Please see attached file for data. Based on what you have seen in all the formulas at this point, Examine the data below and tell me the formula or formulas you would apply to this data, plus what is the IV and the DV. Please solve based on the formula you feel best applies to this data set. In 1987, a consulting orga

Paired T test: Stock Values of Sample A

See attached data file. Use the Current Sample "A" 51 stocks (the current price) and Old Sample "A" (the price for one year ago) to calculate a paired test to determine if there has been a significant change in these stock values in the last year. Explain in detail why this paired test would be appropriate for these data, but

Space Shuttle Challenger: Determine if the MT engineers hypothesis was correct.

See attached file. I am sure many of you remember the fateful event that occurred in 1986 with the Space Shuttle Challenger disaster. I still remember where I was at the time of the explosion. There was much debate between NASA officials, Morton Thiokol (MT) Management (contractors that built the Challenger rocket boosters) a

One Sample T-Test for Comparing Mean

A report states that employees spend, on average, 80 minutes every working day on personal use of the Internet. A company takes a random sample of 100 employees and finds their mean personal Internet use is 83 minutes with a standard deviation of 15 minutes. The company's managing director claims that his employees spend more ti

Determining Degrees of Freedom

What do you mean by degrees of freedom in statistics? Explain the concept of degrees of freedom for each of the following hypothesis tests. Use an example in each case and compute the degrees of freedom. Determine step by step how you arrived at the degrees of freedom. 1. One Sample T-Test 2. Two Sample T-Test for Independ

Paired T Test for Stress Before and After Taking a Drug

A researcher wants to know if there is a difference in people's stress before and after taking a drug. The lower the number, the less their stress level. 30 participants were involved. a) What statistical test should be used? Why? b) Show all steps to analyze data. c) Summarize findings using APA format and including necess

The t Test for Two Related Samples

22. In the Preview section of this chapter, we discussed a report describing how the accuracy of Olympic marksmen can be affected by heartbeats. Pelton (1983) reported that Olympic - level marksmen shoot much better if they fire between heartbeats rather than squeezing the trigger during a heartbeat. The small vibrate caused by

Back Charges Evaluation: Example Problem

Please complete and show all work. An engineering firm is evaluating their back charges. They originally believed their average back charge was $1800. They are concerned that the true average is higher, which could hurt their quarterly earnings. They randomly select 40 customers, and calculate the corresponding sample mean b