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You are a recent graduate of Embry-Riddle Aeronautical University and have been hired by John Jolly to run and interpret a t-test. John is the owner of John’s Jolly Oil Change. John is experimenting with a new oil change process and is trying to determine if the new process takes less time than the old process. John is comparing sample mean times to evaluate his hypothesis about the population (total number of oil changes). Over the period of a week, he took a random sample of oil changes using both the old and new processes. Using the information John provided, you ran a t-test for independent samples. These are the results ( = .05).

t-Test: Two-Sample Assuming Unequal Variance

First, watch this video to become familiar with running and interpreting a t-test in Excel.

Hypothesis Test for 2 Population Means using Excel’s Data Analysis (YouTube 5:39) (Links to an external site.)

Now, think about how you will respond to John. Answer the following questions.

What is the hypothesis in this scenario?
Did the new oil change process take less or more time? How do you know?
In the scenario, did you conduct a one or two-tailed test?
What is the P value? (Round to 3 decimal places)
Do you think (as John does) that the result is not statistically significant?
Do the results prove anything?
Your initial response should be four paragraphs.

Make your initial post by the fourth day of the module week. Return to the discussion later in the module week to read and reply to at least two of your classmates’ posts. In your replies, discuss whether you agree or disagree with the interpretation of the statistical output. Do you think another sample should be taken to see if the initial findings can be replicated? Why or why not?

Your replies should be at least two paragraphs.

Review the Discussion Rubric for detailed grading instructions.