Explore BrainMass

Student's t-Test

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

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

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

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

Describe a real-world problem using a single sample t-test

The principal of your local school announces to the school-community group (of which you are a part) that funding will be cut next year if a higher percentage of the children in the 4th, 5th, and 6th grades do not perform at the expected level of proficiency on the state test. Your principal knows you are a graduate student and

Statistics: t-test for two independent samples

1. One sample has SS= 35 and the second sample has SS=45. a) assume that n=6 for both, calculate the sample variance, and the pooled variance. b) assume that n=6 for one and n=16 for the other, calculate the two sample variances and the pooled variance. 2. A sample of n=10 people receive medication with pain tolerance and

T Statistics

1. indicate whether the factor influence the numerator or denominator of the t statistic and determine whether the effect would be to increase the value of t or decrease the value of t if all other factors rmain constant. a) increase the variability of the scores b) increase the number of scores in the sample c) increase the

T-Test for Dependent Samples

Big Time Software Co. has developed a new version of it XD-3 software. They want to determine if the new version of XD-3 is faster then the old version. In a matched sample test they obtained the following results. Tester Old Version New Version 1 2.6 2.8 2

5-Step Hypothesis Test: Two Sample t-Test

Using the Data Collection attached, perform the following statistical operations and compile your results in a Microsoft Word document: ? State a research (non-directional) hypothesis and a null hypothesis about the populations ? Determine the cutoff sample score of t at ±=.05 ? Calculate a mean and variance for each sampl

T-test or Z-test

You want to determine if your widgets from machine 1 are the same as machine 2. Machine 1 has a sample mean of 2000.21 and a sample standard deviation of 6.1 and a sample size of 2. Machine 2 has a sample mean of 1998.76 and a sample standard deviation of 6.2 with a sample size of 2. With an alpha of .05 can we claim that the

Inferences from Dependent Samples

Car Repair Costs Listed below are the costs in dollars of repairing the front ends and rear ends of different cars when they were damaged in controlled low-speed crash tests. The cars are Toyota, Mazda, Volvo, Saturn, Subaru, Hyundai, Honda, volkswagen, and Nissan. Contruct a 95% confidence interval of the mean of the differe

Statistics: AIU survey responses; two-tailed hypothesis test, t-test, z-test,

See attached data file. Using AIU's survey responses from the AIU data set, complete the following requirements in the form of a report: Perform a two-tailed hypothesis test on both the intrinsic and the extrinsic variable's data, using a .05 significance level. Begin by creating a null and an alternate statement. Use Mic

Independent Sample t test nonnumerical data

I am having a hard time understanding how to perform t-tests in nonnumerical data. A. Perform two t - tests to determine if there is a difference in your spending category based on Card Type or Reward Type. Do people who get World Points spend more than those who get Gas Rebates on your Spend type? Do people with Master

Independent Sample t test credit cards

Using the credit card data that appears on the next tab, analyze Airline Spend. Perform two t-tests to determine if there is a difference in your spending category based on Card Type or Reward Type. Do people who get World Points spend more than those who get Gas Rebates on your Spend type? Do people with Master Cards spend

Independent sample t test: Times required by sprinters

Two groups of ten sprinters run 100 meters. The times required by sprinters in the first group are as follows: 13.7 14.2 13.2 11.3 12.6 10.0 10.1 14.1 13.8 13.2 The times required by sprinters in the second group are as follows: 17.3 10.6 14.0 15.9 15.1 13.4 18.9 17.2 17.6 10.1 Assuming that = 0.05, test


Question 3 Identify the null hypothesis, alternative hypothesis, test statistic, P-value, conclusion about the null hypothesis, and final conclusion that addresses the original claim Various temperature measurements are recorded at different times for a particular city. the mean of 20 degrees celcius is obtained for 40 tempe

The answer to Hypothesis Testing: Independent sample t test

Construct the Two Sample chart using excel, with the data provided? Chapter 11, problem 47 - The city of Laguna Beach operates two public parking lots. The one on Ocean Drive can accommodate up to 125 cars and the one on Rio Rancho can accommodate up to 130 cars. City planners are considering both increasing the size of th

Statistics: Study of perceptual illusions under two different lighting conditions

A psychologist conducts a study of perceptual illusions under two different lighting conditions. Twenty participants were each tested under both of the two different conditions. The experimenter reported: "The mean number of effective illusions was 6.72 under the bright conditions and 6.85 under the dimly lit conditions, a diffe