M3 Assignment (30 points)

Q1. Hypothesis Testing with a Z test (10 points total)

A research institute examined the number of mobile devices (smart phones and tablets) in American households and reported a mean () of 4 devices per household and a standard deviation () of 2 devices. But I wonder if the statistics in my neighborhood, Chandler, would be different from the national average. Specifically, I have a hunch that household in Chandler might have more mobile devices compared to the national average.

To test this idea, I randomly picked 16 friends of mine living in Chandler and asked them how many smart phones and tablets are in their households. The data set is shown below. (The same data are also provided in an Excel file if you choose to use Excel for your calculations.)

I would like to perform a Z test to see if the numbers of mobile devices in Chandler households (represented by the sample of 16 households) are significantly higher than the numbers of mobile devices in the national households. The significance level for my Z test was set at = .05. The hypotheses should be directional because I am predicting a specific direction of difference, and the test should be one-tailed.

Subject # (Household) # of mobile devices

1 6

2 7

3 3

4 6

5 4

6 6

7 5

8 4

9 7

10 4

11 4

12 6

13 5

14 3

15 4

16 6

a. What is the dependent variable in this study? (1 point)