1. INF 397C Fall, Days 13

2. Designing Research Finishing the exercise from last week . . .
Question 3 (groups 5 and 6): Does design of a Web site affect visitors’ perception of the validity of the content?

3. Homework http://www.environ.wa.gov.au/community/results.asp

4. Other “T scores”
“T scores” – “Standardized T scores for the WAIS-R, WISC-R, and HRB”
Yet new “T scores.”

5. Other measures Confidence intervals
Anova

6. Chi-squared
Hinton, p. 239

7. Chi square test Let’s work an example.
Just know that you use the chi square test when you have FREQUENCY data.

8. Correlation
With correlation, we return to DESCRIPTIVE statistics. (This is counterintuitive. To me.)
We are describing the strength and direction of the relationship between two variables.
And how much one variable predicts the other.

9. Hinton,
p. 259

10. Break

11. Let’s conduct some REAL research
Research question: Is one of the two formulae for Standard Deviation easier to use?
H0: µ1 = µ2
HA: µ1 ≠ µ2
Population: iSchool Research Methods students
Sampling technique: Random
IV: Particular formula (derivative formula vs. computational formula
DVs: 1) Speed, 2) Accuracy

12. Procedure Who has a calculator? Number off, 1 to N.
We’re gonna choose 10.
Randomly assign 5 to Group 1 and 5 to Group 2.
Group 1 – Derivative formula first.
Group 2 – Computational formula first.
For each testee (wink), need one volunteer to time the completion.
Test participant: Please start when I say “Go,” and tell your observer when you think you have the answer.

13. Test Materials -- A
Please calculate the Standard Deviation of the following distribution of scores: 5 6 2 8 3 9 4

14. Test Materials -- B
Please calculate the Standard Deviation of the following distribution of scores: 4 6 8 7 3 9 2

15. Scoring Observers, please collect the following data:
Test Participant number
Materials A problem: Correct (y/n)
Materials A problem: Time to complete?
Materials B problem: Correct (y/n)
Materials B problem: Time to complete?
Difference score: Time for derivative (whether it was A or B) minus time for computational formula (whether it was A or B)
Let’s build a spreadsheet with the data.

16. End game Calculate t. Reject or not? Conclusion.
Now, REALLY, to whom do these results generalize?

17. Let’s talk about the final
Course evaluation
Q-and-A session, Monday, December 1, 5:30 – 6:30, place TBD.
Sample problems handed out next week.