Regression Analysis: Height Versus Thumb Length, Thumb Length Versus Texting Time

AOS-HCI Research Module 2010 Worksheet 2

Regression Analysis: Height versus Thumb Length, Thumb Length versus Texting Time 1. How does one graph Height in Fathom?

2. Moving on, how does one graph Height versus Thumb Length in Fathom and Excel?

3. What is the interpretation of R2?

Hypothesis Testing

4. What is the null hypothesis?

5. What is the alternative (or test) hypothesis?

6. What is statistical significance?

7. How does one interpret the p value? How can we use the p value in the hypothesis testing?

8. Referring to the MCAT Myth Chart, how does one interpret the Means ± SEM? Die Rolling Experiment 9. Grab two dice and roll them for 48 times. Record the sum of each roll in an Excel spreadsheet. The Excel File can be downloaded from Mr Writer’s AOS website. 10. Note the Mean and the Standard Deviation of the Real Die Roll.

Construction of Confidence Interval in Fathom 11. Dowload the file Workshop Spreadsheet II file (theoretical.csv) from Mr Writer’s AOS website. 12. Open Fathom and import the above file.

→ 13. Highlight the “theoretical” icon in Fathom and drag the “Table” icon down in the empty space. 14. Now with the Table icon highlighted, drag the “Summary” icon down.

15. Next, drag the column “Theoretical” over to the attribute.

2 16. Right-click on any empty space in the “Summary” dialogue and select “Add Basic Statistics”

17. Your screen should like the following:

18. Next, move your mouse down below the x-axis and right-click in this area. Choose Plot Function

3 19. Select Function, Distribution, Normal and finally double-click on Normal Density.

20. Enter the variable (in this case, x), then a comma, then the mean of your sample, then a comma, and finally the standard deviation divided by the square root of the sample size.

21. Your graph should look like this:

4 22. Next. Right click on an empty space below the x-axis and select Plot Value. 23. Type in the Value dialogue box, . Repeat for

24. Adjust your graph to look like this:

25. The region between the two lines represents the 95% confidence interval (C.I.). What does it mean?

26. Now, repeat the above on your own for the actual die roll data. 27. You should have two graphs side by side. Interpret the two graphs and their 95% confidence intervals. For example, do the two C.I. overlap and if they do, what does that mean?

28. Finally, what can you infer from your interpretation above?

5 Perform t-test in Excel 29. Perform t-test in Excel, comparing this mean with the theoretical mean, using the following steps: a. Ensure that you have included the Analysis ToolPak by going to Tools → Add-Ins → Analysis ToolPak

b. Go to Tools → Analysis ToolPak, scroll downwards to select t- Test: Two Sample Assuming Unequal Variance.

→ c. Select the data in theoretical sum as Range 1, and the data in Actual Die Rolling Outcome as Range 2. d. Input Hypothesized Mean Difference as 0. e. Click on Output Range and select any empty cell in the spreadsheet. f. Click OK. g. Interpret the result.