1. Sample Presentation

2. Research Question Do students who own graphing calculators study more than students who do not? Do students who own graphing calculators study more than students who do not? Specifically, how do these two groups compare on the average number of hours spent studying in a typical week? Specifically, how do these two groups compare on the average number of hours spent studying in a typical week?

3. Variables used I used Q13: Do you own a graphing calculator? to form two groups. I used Q13: Do you own a graphing calculator? to form two groups. I used Q31: How many hours do you study in a typical week? as a quantitative variable. I used Q31: How many hours do you study in a typical week? as a quantitative variable.

4. Hours studied by students who do own graphing calculators

5. Students who own graphing calculators 45 people in the sample own graphing calculators 45 people in the sample own graphing calculators The average number of hours they study in a typical week is 21.7 hours, with a standard deviation of 14.0 hours. The average number of hours they study in a typical week is 21.7 hours, with a standard deviation of 14.0 hours. The histogram is not symmetric: it has a right hand tail. The histogram is not symmetric: it has a right hand tail.

6. Hours studied by students without graphing calculators

7. Students without graphing calculators 14 people in the sample don’t own graphing calculators. 14 people in the sample don’t own graphing calculators. On average they study 19.4 hours in a typical week, with a standard deviation of 8.7 hours. (This is SD+) On average they study 19.4 hours in a typical week, with a standard deviation of 8.7 hours. (This is SD+) The histogram is roughly symmetric, although more people study 20-30 hours than study 10 to 20 hours. The histogram is roughly symmetric, although more people study 20-30 hours than study 10 to 20 hours.

8. Hypothesis testing Null hypothesis: there is no difference between the average number of hours studied in a typical week between students with a graphing calculator and students without. Null hypothesis: there is no difference between the average number of hours studied in a typical week between students with a graphing calculator and students without. Alternate hypothesis: Students who own a graphing calculator spend more time on homework. Alternate hypothesis: Students who own a graphing calculator spend more time on homework.

9. Calculating SEavg for each group With graphing calculator: With graphing calculator: SE avg = sqrt(45) x 14/45 = 2.1 hours With no graphing calculator: SE avg = sqrt(14) x 8.7/14 = 2.3 hours

10. SE for the difference The SE for the difference between these two averages is The SE for the difference between these two averages is SEdiff = sqrt(2.3 2 + 2.1 2 ) SEdiff = sqrt(2.3 2 + 2.1 2 ) SEdiff = 3.1 hours SEdiff = 3.1 hours

11. 2-sample z-test The difference between the two averages is 21.7 – 19.4 = 2.3 The difference between the two averages is 21.7 – 19.4 = 2.3 The z-value for this difference is The z-value for this difference is 2.3/SEdiff = 2.3/3.1 = 0.74 The area under the normal curve to the right of z = 0.74 is approx (100-54)/2 = 23% P = 23% is much larger than 5% P = 23% is much larger than 5%

12. Conclusion We have to accept the null hypothesis. There is no difference between students with and those without graphing calculators in the average number of hours of study in a typical week. We have to accept the null hypothesis. There is no difference between students with and those without graphing calculators in the average number of hours of study in a typical week.