1. Scientific Method: Activity 1 – Hypothesis Testing
Week of January 22nd, 2018

2. Pre-lab checklist Attendance policy Honor Code Lab book
Technology in the classroom
Lab safety
Office of Disability Services (ds.gmu.edu)
Grading
Online textbook
Weekly Data Sheet (due at end of class)
Weekly Write-Up (due at beginning of next class)

3. Introductions

4. Introduction Professor Walker nwalker3@gmu.edu
Office: Rm 3038 (hours by appointment only)
Research: American eel (Anguilla rostrata) conservation

5. Teaching triangle (Walker 2017)
Inspired by Tsukamoto (2014)

6. https://eeltown.org/2018/01/01/book-review-the-pond-by-carl-ewald/

7. Field trips (extra credit)
Saturday, February 3rd – Huntley Meadows Park 11 a.m.
Saturday, March 3rd – C&O Canal / Great Falls National Park 9 a.m.
(More to come…)
To receive 8 points of extra credit, you must:
Arrive on time and participate in the entire field trip.
Write a two page (double spaced) paper on how the location relates to environmental science and/or conservation.

9. The Scientific Method At every step: Communicate with other scientists
Fits with current scientific theories or laws
Make observations
Ask questions
Formulate hypotheses
Test Hypotheses
Develop new scientific theory or law
At every step: Communicate with other scientists
Revise hypotheses

10. What is a hypothesis?
Tentative explanation of a phenomenon, phrased in such a way as to be testable.
Null hypothesis (H0)
Alternative hypothesis (HA)

11. Activity 1 – Hypothesis Testing
Part A – Hypothesis Development
As a class, brainstorm factors that might affect reaction time.

12. Group-level Hypotheses
Each group will test ONE factor.
Develop null and alternative hypotheses based on your assigned factor.
Record your group’s hypothesis in Table 1.1.
Group-level Hypotheses
H0:
HA:
Table 1.1

13. Record factors being investigated by each group (Table 1.2).
Group member
Johnny
Jimmy
Julie
Jenny
Trial # 
Catch Distance (cm)
Reaction Time (sec)
Catch Distance (cm) 1
3.3
1.5
0.8
2.2 2
3.5
1.6
0.9
2.1 3
2.8
0.7
2.0 4
1.7
1.9
Mean =
0.076
0.057
0.040
0.064
Factor by Group
Group #
Factor
GPA
>2.0
<2.0
Mom’s age
>45
<45
Dad salary
>100,000
<100,000
Dog’s ears
Pointy
Floppy 5
Hair len
>10in
<10in 6
Vehicle
4WD
2WD
Record factors being investigated by each group (Table 1.2).
Table 1.2

14. Work in pairs within lab group to determine reaction time for each student.
Conduct four trials.
One member will be the “dropper”.
The other will be the “catcher”.
Reverse roles and conduct four additional trials.

15. Catcher
Dropper
Catcher holds out hand with thumb & index finger outstretched, ready to catch ruler.
Dropper holds ruler above outstretched thumb & index finger of catcher (zero mark on ruler should be level with top of catcher’s thumb) .
Dropper drops ruler without warning.
Catcher catches ruler (between thumb &index finger) as quickly as possible after it is dropped
Catcher holds ruler in exact position in which it was caught until the distance (in cm) is determined (between zero mark on ruler and top of catcher’s thumb where ruler has been caught).

16. Group member
Johnny
Jimmy
Julie
Jenny
Trial # 
Catch Distance (cm)
Reaction Time (sec)
Catch Distance (cm) 1
3.3
1.5
0.8
2.2 2
3.5
1.6
0.9
2.1 3
2.8
0.7
2.0 4
1.7
1.9
Mean =
0.076
0.057
0.040
0.064
Factor by Group
Group #
Factor
GPA
>2.0
<2.0
Mom’s age
>45
<45
Dad salary
>100,000
<100,000
Dog’s ears
Pointy
Floppy 5
Hair len
>10in
<10in 6
Vehicle
4WD
2WD
Record catch distance for each person for each trial, and the mean for each person’s four trials (Table 1.2).
Table 1.2

17. Distance fallen (in cm) = (1/2)(980 cm/sec2)t2
Group member
Johnny
Jimmy
Julie
Jenny
Trial # 
Catch Distance (cm)
Reaction Time (sec)
Catch Distance (cm) 1
3.3
1.5
0.8
2.2 2
3.5
1.6
0.9
2.1 3
2.8
0.7
2.0 4
1.7
1.9
Mean =
0.076
0.057
0.040
0.064
Factor by Group
Group #
Factor
GPA
>2.0
<2.0
Mom’s age
>45
<45
Dad salary
>100,000
<100,000
Dog’s ears
Pointy
Floppy 5
Hair len
>10in
<10in 6
Vehicle
4WD
2WD
Based on:
Distance fallen (in cm) = (1/2)(980 cm/sec2)t2
Convert each catch distance in cm to reaction time in seconds using the formula:
t = (sqrt(d/490)) (where sqrt = square root)
Record results (Table 1.2).
Table 1.2

18. Mean Reaction Time (sec)
Transfer mean reaction time and factor data from Table 1.2 to Table 1.3.
Record data for the rest of the class in Table 1.3.
Group member
Johnny
Jimmy
Julie
Jenny
Trial # 
Catch Distance (cm)
Reaction Time (sec)
Catch Distance (cm) 1
3.3
1.5
0.8
2.2 2
3.5
1.6
0.9
2.1 3
2.8
0.7
2.0 4
1.7
1.9
Mean =
0.076
0.057
0.040
0.064
Factor by Group
Group #
Factor
GPA
>2.0
<2.0
Mom’s age
>45
<45
Dad’s salary
>100,000
<100,000
Dog’s ears
Pointy
Floppy 5
Hair length
>10in
<10in 6
Vehicle type
4WD
2WD
Group factors
Mean Reaction Time (sec)
Group # 1 2 3 4 5 6
Student
Factor
GPA
Mom’s age
Dad’s salary
Dog’s ears
Hair length
Vehicle type
Johnny
0.076
>2.0
>45
>100,000
Pointy
>10in
4WD
Jimmy
0.057
etc
Julie
0.040
Jenny
0.064
Jorge
???
Joaquin
June
Joe
Table 1.2
Table 1.3

19. Mean Student Reaction Time (sec)
Record the two categories of your group’s factor (Table 1.4).
Use data (Table 1.3) to transfer mean reaction time per student to Table 1.4.
Complete Table 1.4 by calculating the mean of the student mean reaction times for the two categories for your group’s factor.
Mean Student Reaction Time (sec)
Factor:
Mom’s age <45
Mom’s age >45
0.057
0.076
0.040
0.064
0.004
0.001
etc
0.002
0.003
Mean of the means:
???
Table 1.4

20. Part C – Data Analysis
Go to ats/t-test_bulk_form.html
Tool to calculate student’s t-test of two means.

21. Record the t value, probability value and conclusion under “student’s t test results” (Table 1.5).
1.64
Probability:
0.113
Null Hypothesis Rejected (p ≤ 0.05) or accepted (p > 0.05):
Accepted
Conclusion:
There is no difference in reaction time for people
whose mothers are >45 years old as compared to those whose
mothers are <45 years old.

22. What’s Due Today: Next class: Lab Safety Form.
Activity 1 – Hypothesis testing data sheet.
Next class:
Activity 1 – Hypothesis testing write-up.